Patent Publication Number: US-2017372204-A1

Title: Methods and apparatus for providing information of interest to one or more users

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application is a continuation of U.S. patent application Ser. No. 15/164,952, filed on May 26, 2016, titled “Methods and Apparatus for Providing Information of Interest to One or More Users”. U.S. patent application Ser. No. 15/164,952 claims the benefit under 35 U.S.C. §119(e) of U.S. Provisional Application Ser. No. 61/428,435, filed on Dec. 30, 2010, titled “Method and Apparatus for Semantic Query Expansion,” attorney docket No. P0913.70015US00, and of U.S. Provisional Application Ser. No. 61/428,445, filed Dec. 30, 2010, titled “Method and Apparatus for Displaying Promotional Content,” attorney docket No. P0913.70016US00, and of U.S. Provisional Application Ser. No. 61/428,676, filed Dec. 30, 2010, titled “Method and Apparatus for Spatio-Temporal Semantic Synthesis,” attorney docket number P0913.70018US00, and of U.S. Provisional Application Ser. No. 61/430,090, filed Jan. 5, 2011, titled “Method and Apparatus for Generating Semantically Proximate Concepts,” attorney docket number P0913.70020US00. U.S. patent application Ser. No. 15/164,952 is also a continuation-in-part of U.S. patent application Ser. No. 13/162,069 filed on Jun. 16, 2011, titled “Methods and Apparatus for Searching of Content Using Semantic Synthesis,” attorney docket No. P0913.70013US01. 
     U.S. patent application Ser. No. 13/162,069 claims the benefit under 35 U.S.C. §119(e) of U.S. Provisional Application Ser. No. 61/357,512, filed on Jun. 22, 2010, titled “Methods and Apparatus for Searching of Content Using Semantic Synthesis,” attorney docket number P0913.70013US00, and of U.S. Provisional Application Ser. No. 61/430,138, filed Jan. 5, 2011, titled “Methods and Apparatus for Presenting Concepts Related to an Active Concept,” attorney docket number P0913.70024US00, and of U.S. Provisional Application Ser. No. 61/430,141, filed Jan. 5, 2011, titled “Methods and Apparatus for Identifying Terms for Monetization,” attorney docket number P0913.70021US00, and of U.S. Provisional Application Ser. No. 61/430,143, filed Jan. 5, 2011, titled “Methods and Apparatus for Taking an Advertising Action Using a Bot,” attorney docket number P0913.70023US00. U.S. patent application Ser. No. 13/162,069 is also a continuation-in-part of U.S. patent application Ser. No. 12/671,846 filed on Feb. 2, 2010, titled “Method System, and Computer Program for User-Driven Dynamic Generation of Semantic Networks and Media Synthesis,” attorney docket No. P0913.70007US00. 
     U.S. patent application Ser. No. 12/671,846 is the National Stage, under 35 U.S.C. §371, of International Application No. PCT/CA2009/000567 filed May 1, 2009, titled “Method, System, and Computer Program for User-Driven Dynamic Generation of Semantic Networks and Media Synthesis,” which claims the benefit under U.S.C. §119(e) of U.S. Provisional Application Ser. No. 61/049,581 filed on May 1, 2008, titled “Method, System, and Computer Program for User-Driven Dynamic Generation of Semantic Networks.” All of the above-mentioned applications are hereby incorporated by reference in their entireties. 
    
    
     FIELD OF INVENTION 
     The teachings disclosed herein relate to the field of information retrieval. In particular, the teachings disclosed herein relate to the deployment of methods, in a digital information system environment, for using information associated with a user or users together with one or more data sets expressed as knowledge representations in order to identify and provide information, from a larger set of digital content, that may be of interest to the user(s). 
     BACKGROUND 
     Information technology is often used to provide users with various types of information, such as text, audio, video, and any suitable other type of information. In some cases, information is provided to a user in response to an action that the user has taken. For example, information may be provided to a user in response to a search query input by the user or in response to the user&#39;s having subscribed to content such as an e-mail alert(s) or a electronic newsletter(s). In other cases, information is provided or “pushed” to a user without the user having specifically requested such information. For example, a user may occasionally be presented with advertisements or solicitations. 
     There is a vast array of content that can be provided to users via information technology. Indeed, because of the enormous volume of information available via the Internet, the World Wide Web (WWW), and any other suitable information provisioning sources, and because the available information is distributed across an enormous number of independently owned and operated networks and servers, locating information of interest to users presents challenges. Similar challenges exist when the information of interest is distributed across large private networks. 
     Search engines have been developed to aid users in locating desired content on the Internet. A search engine is a computer program that receives a search query from a user (e.g., in the form of a set of keywords) indicative of content desired by the user, and returns information and/or hyperlinks to information that the search engine determines to be relevant to the user&#39;s search query. 
     Search engines typically work by retrieving a large number of WWW web pages and/or other content using a computer program called a “web crawler” that explores the WWW in an automated fashion (e.g., following every hyperlink that it comes across in each web page that it browses). The located web pages and/or content are analyzed and information about the web pages or content is stored in an index. When a user or an application issues a search query to the search engine, the search engine uses the index to identify the web pages and/or content that it determines to best match the user&#39;s search query and returns a list of results with the best-matching web pages and/or content. Frequently, this list is in the form of one or more web pages that include a set of hyperlinks to the web pages and/or content determined to best match the user&#39;s search query. 
     The sheer volume of content accessible via digital information systems presents a number of information retrieval problems. One challenging problem is how to determine what information, in a large set of content, may be of interest to users so that such information may be presented to the users without overwhelming them with irrelevant information. A related problem is how to determine what information may be of interest to users that may be searching for information in a large set of content by using terms that appear infrequently in the set of content being searched. Accordingly, the inventors have recognized the need for techniques for identifying information of interest to users in a large set of content and presenting such content to the users. These needs are addressed herein with a new methodology and applications. 
     SUMMARY 
     In some embodiments, a computer-implemented method for providing information selected from a large set of digital content to at least one user is disclosed. The method comprises receiving user context information associated with the at least one user; identifying or generating, using at least one processor executing stored program instructions, a first concept in a semantic network, the first concept representing at least a portion of the user context information; obtaining at least one concept, including a second concept, semantically relevant to the first concept at least in part, by synthesizing the second concept based on the first concept and at least one other concept in the semantic network; and providing information to the at least one user, wherein the information is selected by using the first concept and the at least one obtained concept semantically relevant to the first concept, wherein the first concept in the semantic network is represented by a data structure storing data associated with a node in the semantic network. 
     In some embodiments, a system for providing information selected from a large set of digital content to at least one user is disclosed. The system comprises at least one processor configured to perform a method comprising receiving user context information associated with the at least one user; identifying or generating a first concept in a semantic network, the first concept representing at least a portion of the user context information; obtaining at least one concept, including a second concept, semantically relevant to the first concept at least in part, by synthesizing the second concept based on the first concept and at least one other concept in the semantic network; and providing information to the at least one user, wherein the information is selected by using the first concept and the at least one obtained concept semantically relevant to the first concept, wherein the first concept in the semantic network is represented by a data structure storing data associated with a node in the semantic network. 
     In some embodiments, at least one non-transitory computer readable storage medium is disclosed. The at least one non-transitory computer readable storage medium stores processor-executable instructions that when executed by at least one processor, cause the at least one processor to perform a method for providing information selected from a large set of digital content to at least one user. The method comprises receiving user context information associated with the at least one user; identifying or generating a first concept in a semantic network, the first concept representing at least a portion of the user context information; obtaining at least one concept, including a second concept, semantically relevant to the first concept at least in part, by synthesizing the second concept based on the first concept and at least one other concept in the semantic network; and providing information to the at least one user, wherein the information is selected by using the first concept and the at least one obtained concept semantically relevant to the first concept, wherein the first concept in the semantic network is represented by a data structure storing data associated with a node in the semantic network. 
     In some embodiments, synthesizing the second concept comprises identifying the at least one other concept in the semantic network based at least in part on the structure of the semantic network, and synthesizing the second concept from the first concept and the at least one other concept. 
     In some embodiments, synthesizing the second concept comprises using an addition operation based on at least one of an attribute co-definition technique, an analogy-by-parent technique, an analogy-by-sibling technique, and/or an attribute commonality technique. 
     In some embodiments, synthesizing the second concept comprises using a substitution operation, wherein the substitution operation comprises using a retrieval operation and/or an addition operation. 
     In some embodiments, obtaining the at least one concept comprises obtaining a plurality of concepts semantically relevant to the first concept; computing a score for one or more concepts in the plurality of concepts, wherein the score for a specific concept is indicative of the semantic relevance of the specific concept to the first concept; and selecting the at least one concept based on the scores computed for the one or more concepts. 
     In some embodiments, computing a score for a concept comprises using at least one measure of relevance from among generation certainty, concept productivity, Jaccard, statistical coherence, and/or cosine similarity. 
     In some embodiments, a computer-implemented method for providing information selected from a large set of digital content, by using a user-specific knowledge representation, to at least one user is disclosed. The method comprises receiving user context information associated with the at least one user; identifying or generating, using at least one processor executing stored program instructions, a first concept in the user-specific knowledge representation representing at least information associated with the user, the first concept representing at least a portion of the user context information; obtaining at least one concept in the user-specific knowledge representation that is semantically relevant to the first concept; and providing information to the at least one user, wherein the information is selected by using the first concept and the at least one obtained concept semantically relevant to the first concept, wherein a concept in the user-specific knowledge representation is represented by a data structure storing data associated with a node in the user-specific knowledge representation. 
     In some embodiments, a system for providing information selected from a large set of digital content, by using a user-specific knowledge representation, to at least one user is disclosed. The system comprises at least one processor configured to execute a method comprising receiving user context information associated with the at least one user; identifying or generating, using at least one processor executing stored program instructions, a first concept in the user-specific knowledge representation representing at least information associated with the user, the first concept representing at least a portion of the user context information; obtaining at least one concept in the user-specific knowledge representation that is semantically relevant to the first concept; and providing information to the at least one user, wherein the information is selected by using the first concept and the at least one obtained concept semantically relevant to the first concept, wherein a concept in the user-specific knowledge representation is represented by a data structure storing data associated with a node in the user-specific knowledge representation. 
     In some embodiments, at least one non-transitory computer-readable storage medium is disclosed. The at least one non-transitory computer-readable storage medium stores processor-executable instructions that when executed by at least one processor, cause the at least one processor to perform a method for providing information selected from a large set of digital content, by using a user-specific knowledge representation, to at least one user. The method comprises receiving user context information associated with the at least one user; identifying or generating, using at least one processor executing stored program instructions, a first concept in the user-specific knowledge representation representing at least information associated with the user, the first concept representing at least a portion of the user context information; obtaining at least one concept in the user-specific knowledge representation that is semantically relevant to the first concept; and providing information to the at least one user, wherein the information is selected by using the first concept and the at least one obtained concept semantically relevant to the first concept, wherein a concept in the user-specific knowledge representation is represented by a data structure storing data associated with a node in the user-specific knowledge representation. 
     In some embodiments, the method may further comprise determining whether a saved user-specific knowledge representation associated with the user exists; using the saved user-specific knowledge representation as the user-specific knowledge representation when it is determined that the saved user-specific knowledge representation exists, and generating a new user-specific knowledge representation and using it as the user-specific knowledge representation, when it is determined that the saved user-specific knowledge representation does not exist. 
     In some embodiments, the at least one concept comprises a second concept, and obtaining the at least one concept comprises synthesizing the second concept based at least in part on the structure of the user-specific knowledge representation. 
     In some embodiments, synthesizing the second concept comprises using an addition operation based on at least one of an attribute co-definition technique, an analogy-by-parent technique, an analogy-by-sibling technique, and/or an attribute commonality technique. 
     In some embodiments, synthesizing the second concept comprises using a substitution operation, wherein the substitution operation comprises using a retrieval operation and/or an addition operation. 
     In some embodiments, obtaining the at least one concept comprises obtaining a plurality of concepts semantically relevant to the first concept; computing a score for one or more concepts in the plurality of concepts, wherein the score for a specific concept is indicative of the semantic relevance of the specific concept to the first concept; and selecting the at least one concept based on the scores computed for the one or more concepts. 
     In some embodiments, computing a score for a concept comprises using at least one measure of relevance from among generation certainty, concept productivity, Jaccard, statistical coherence, and/or cosine similarity. 
     In some embodiments, a computer-implemented method of searching for content in a target set of content based on a reference set of content, a reference semantic network representing knowledge associated with the reference set of content, and a target semantic network representing knowledge associated with the target set of content, is disclosed. The method comprises receiving a user-specified search query; obtaining, by using at least one processor executing stored program instructions, at least one concept semantically relevant to the user-specified search query by using the target semantic network and the reference semantic network; constructing a second search query by augmenting the first search query with one or more terms associated with the at least one obtained concept; providing, to the at least one user, content associated with search results obtained based at least in part on searching the target set of content by using the second search query, wherein any concept in the semantic network is represented by a data structure storing data associated with a node in the semantic network. 
     In some embodiments, a system for searching for content in a target set of content based on a reference set of content, a reference semantic network representing knowledge associated with the reference set of content, and a target semantic network representing knowledge associated with the target set of content, is disclosed. The system comprises at least one processor configured to perform a method comprising receiving a user-specified search query; obtaining, by using at least one processor executing stored program instructions, at least one concept semantically relevant to the user-specified search query by using the target semantic network and the reference semantic network; constructing a second search query by augmenting the first search query with one or more terms associated with the at least one obtained concept; providing, to the at least one user, content associated with search results obtained based at least in part on searching the target set of content by using the second search query, wherein any concept in the semantic network is represented by a data structure storing data associated with a node in the semantic network. 
     In some embodiments, at least one non-transitory computer-readable storage medium is disclosed. The at least one non-transitory computer-readable storage medium stores processor-executable instructions that when executed by at least one processor, cause the at least one processor to perform a method of searching for content in a target set of content based on a reference set of content, a reference semantic network representing knowledge associated with the reference set of content, and a target semantic network representing knowledge associated with the target set of content. The method comprises receiving a user-specified search query; obtaining, by using at least one processor executing stored program instructions, at least one concept semantically relevant to the user-specified search query by using the target semantic network and the reference semantic network; constructing a second search query by augmenting the first search query with one or more terms associated with the at least one obtained concept; providing, to the at least one user, content associated with search results obtained based at least in part on searching the target set of content by using the second search query, wherein any concept in the semantic network is represented by a data structure storing data associated with a node in the semantic network. 
     In some embodiments, obtaining the at least one concept semantically relevant to the first search query comprises constructing a merged semantic network based on the reference semantic network and the target semantic network; identifying or generating a first concept in the merged semantic network, the first concept representing the user-specified search query; obtaining the at least one concept, including a second concept, semantically relevant to the first concept at least in part by synthesizing the second concept based on the first concept and at least one other concept in the merged semantic network. 
     In some embodiments, constructing the merged semantic network comprises merging the reference semantic network and the target semantic around a concept the reference semantic network and the target semantic network have in common. 
     In some embodiments, constructing the merged semantic network comprises pruning one or more concepts from the reference semantic network and/or from the target semantic network prior to the merging. 
     In some embodiments, synthesizing the second concept comprises using an addition operation based on at least one of an attribute co-definition technique, an analogy-by-parent technique, an analogy-by-sibling technique, and/or an attribute commonality technique. 
     In some embodiments, synthesizing the second concept comprises using a substitution operation, wherein the substitution operation comprises using a retrieval operation and/or an addition operation. 
     In some embodiments, obtaining the at least one concept comprises obtaining a plurality of concepts semantically relevant to the first concept; computing a score for one or more concepts in the plurality of concepts, wherein the score for a specific concept is indicative of the semantic relevance of the specific concept to the first concept; and selecting the at least one concept based on the scores computed for the one or more concepts. 
     In some embodiments, computing a score for a concept comprises using at least one measure of relevance from among generation certainty, concept productivity, Jaccard, statistical coherence, and/or cosine similarity. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       The accompanying drawings are not intended to be drawn to scale. Like elements are identified by the same or like reference designations when practical. For purposes of clarity, not every component may be labeled in every drawing. In the drawings: 
         FIG. 1  is a flowchart of an illustrative process for providing a user with information selected from a large set of digital content, in accordance with some embodiments of the present disclosure. 
         FIG. 2  is a block diagram of an illustrative client/server architecture that may be used to implement some embodiments of the present disclosure. 
         FIG. 3  is a flowchart of an illustrative process for identifying or generating an active concept representing user context information, in accordance with some embodiments of the present disclosure. 
         FIG. 4  is an illustration of generating an active concept representing user context information, in accordance with some embodiments of the present disclosure. 
         FIGS. 5A-5H  illustrate various approaches for obtaining concepts relevant to an active concept representing user context information, in accordance with some embodiments of the present disclosure. 
         FIGS. 6A-6B  illustrate techniques for scoring concepts relevant to an active concept, in accordance with some embodiments of the present disclosure. 
         FIG. 7  is a flowchart of an illustrative process for searching for content in a target set of content based on a reference set of content based on multiple knowledge representations, in accordance with some embodiments of the present disclosure. 
         FIGS. 8A-8C  show an illustrative example of creating a merged knowledge representation by using multiple knowledge representations, in accordance with some embodiments of the present disclosure. 
         FIGS. 9A-9B  show another illustrative example of providing a user with information based on multiple knowledge representations, in accordance with some embodiments of the present disclosure. 
         FIG. 10  is a block diagram of a computing device on which some embodiments of the present disclosure may be implemented. 
     
    
    
     The foregoing is a non-limiting summary of the invention, which is defined by the attached claims. 
     DETAILED DESCRIPTION 
     As noted above, the availability of a large volume of information, from various information-provisioning sources such as the Internet, makes it difficult to determine what information may be of interest to users and should be presented to them. For example, it may be difficult to determine what information (e.g., news, advertisements, updates about other people, etc.) should be presented to a user on a website (e.g., a news website, a web portal, a social networking website, etc.) after the user navigates to the website, but without explicitly specifying what information the user is interested in. 
     Even in a scenario, such as online search, where the user provides an explicit indication (e.g., a search query) of what information the user may be interested in, such an indication may not be sufficient to accurately identify the content to present to the user from among the large set of content that may be presented to the user. Most conventional search engines simply perform pattern matching between the literal terms in the user&#39;s search query and literal terms in the content indexed by the search engine to determine what pieces of content are relevant to the user&#39;s query. As such, when the terms in the user&#39;s search query do not match the literal terms in the indexed content, the user may not be provided with the information the user is seeking. Also when a user enters a search query containing a term whose meaning is ambiguous, the user may be provided with information entirely unrelated to the meaning of the term that the user intended. As such, the user may be overwhelmed with information irrelevant to the user&#39;s interests. 
     In these and other settings, semantic processing techniques may be used to identify information, from among a large set of digital content, that the user is likely to be interested in. In particular, applying semantic processing techniques to information associated with a user may help to identify the information in which the user may be interested. As described in greater detail below, information associated with a user may include, but is not limited to, information about the user (e.g., demographic information, geo-spatial information, the user&#39;s browsing history, etc.) and/or any information provided by the user (e.g., a search query or queries provided by the user, a user-constructed online profile, etc.). 
     Aspects of semantic processing techniques relate to constructing and using knowledge representations to support machine-based storage, knowledge management, and reasoning systems. Conventional methods and systems exist for utilizing knowledge representations (KRs) constructed in accordance with various types of knowledge representation models, which may be realized as concrete data structures, including structured controlled vocabularies such as taxonomies, thesauri, and faceted classifications; formal specifications such as semantic networks and ontologies; and unstructured forms such as documents based in natural language. 
     While it is not intended that the claimed invention be limited to specific knowledge representations, a preferred form is the type of formal specification referred to as a semantic network. Semantic networks are explained in many sources, noteworthy among them being U.S. application Ser. No. 12/671,846, titled “Method, System, And Computer Program For User-Driven Dynamic Generation Of Semantic Networks And Media Synthesis” by Peter Sweeney et al., which is hereby incorporated by reference. 
     Semantic networks have a broad utility as a type of knowledge representation. As machine-readable data, they can support a number of advanced technologies, such as artificial intelligence, software automation and agents, expert systems, and knowledge management. Additionally, they can be transformed into various forms of media (i.e., other KRs). In other words, the synthesis or creation of semantic networks can support the synthesis of a broad swath of media to extract additional value from the semantic network. 
     In some embodiments, a semantic network may be represented as a data structure embodying a directed graph comprising vertices or nodes that represent concepts, and edges that represent semantic relations between the concepts. The data structure embodying a semantic network may be encoded (i.e., instantiated) in a non-transitory, tangible computer-readable storage medium. As such, a semantic network may be said to comprise one or more concepts. Each such concept may be represented by a data structure storing any data associated with one or more nodes in the semantic network representing the concept. An edge in the directed graph may represent any of different types of relationships between the concepts associated with the two nodes that the edge connects. For instance, the relationship represented by an edge in a semantic network may be a “defined-by” relationship or an “is-a” relationship. In the drawings (e.g.,  FIGS. 5A-5H ,  FIGS. 8A-8C , etc.) that show illustrative semantic networks, “defined-by” relationships are indicated by edges ending with a filled-in circle and “is-a” relationships are indicated by edges ending with an arrow. For example, reference numeral  808  identifies a “defined-by” relationship and reference numeral  806  identifies an “is-a” relationship. 
     Concepts may be defined in terms of compound levels of abstraction through their relationships to other entities and structurally in terms of other, more fundamental KR entities such as keywords and morphemes. Such a structure may be referred to as a concept definition. Collectively, the more fundamental knowledge representation entities such as keywords and morphemes that comprise concepts are referred to as attributes of the concept. 
     As explained in U.S. patent application Ser. No. 12/671,846, concepts may be defined in terms of compound levels of abstraction through their relationship to other entities and structurally in terms of other, more fundamental knowledge representation entities such as keywords and morphemes. Such a structure may be referred to as a “concept definition.” 
     Information associated with a user may be used together with at least one knowledge representation, such as a semantic network, in order to infer what information may be of interest to the user. Any suitable knowledge representation may be used. For example, a semantic network representing knowledge associated with content, a subset of which may be of interest to the user, may be used. Such a KR may be constructed from any of numerous data sources including any suitable information provisioning sources and vocabularies. 
     Further, information associated with the user may be used together with one or more knowledge representations to identify concepts semantically relevant to information associated with the user. In turn, the identified concepts may be used to determine what information may be of interest to the user in a broad range of applications. For example, finding concepts that are semantically relevant to terms in a user&#39;s search query may be useful in determining the semantic meaning of the query and what information the user may be seeking. The query may then be augmented with keywords derived from the identified concepts and improved search results may be returned to the user. As another example, concepts identified as being semantically relevant to information contained in a user&#39;s online profile may be useful in determining what information (e.g., advertisements, news, etc.) to present to the user when that user is online. 
     Accordingly, in some embodiments, methods for identifying concepts semantically relevant to information associated with the user are disclosed. A concept representing at least a portion of the information associated with a user, termed an “active concept,” may be identified or synthesized (i.e., generated) and one or more concepts semantically relevant to the active concept may be obtained. In some instances, concepts semantically relevant to the active concept may be identified in a semantic network; but in other instances, concepts relevant to the active concept may be synthesized by using the active concept and at least one other concept in the semantic network. Concepts semantically relevant to the active concept may be identified and/or synthesized based at least in part on the structure of the semantic network. 
     In some embodiments, after concepts semantically relevant to the active concept are obtained, the obtained concepts may be scored. The scores may be calculated in any of numerous ways and, for example, may be calculated based at least in part on the structure of (the data structure of the graph embodying) the semantic network. In turn, the scores may be used to select a subset of the concepts semantically relevant to the active concept. Then, the selected concepts may be used to provide the user with information in which the user may be interested. 
     In some embodiments, information associated with one or more users may be used to construct a user-specific knowledge representation corresponding to the user(s). The user-specific knowledge representation may be constructed from information associated with the user(s) and at least one knowledge representation, such as a semantic network. Accordingly, a user-specific knowledge representation may encode information related to the user(s). Any suitable knowledge representation may be used including, but not limited to, a knowledge representation that represents knowledge associated with content, a subset of which the user(s) may be interested in. The resulting user-specific knowledge representation may be used to identify concepts related to information in which the user(s) may be interested. 
     Advantageously, in some embodiments, a user-specific knowledge representation may be stored and used multiple times. This allows semantic processing for a user to take advantage of previously-performed semantic processing for the user and/or one or more other users. For example, if a user-specific knowledge representation was generated based on information associated with one user in a group of users (e.g., an employee of company X), the same user-specific knowledge representation may be used to identify concepts semantically relevant to information associated with another user in the same group (e.g., another employee of company X). 
     As previously mentioned, it is often the case that, when users search for information, the terms used in their search queries may not literally match the terms appearing in the content being searched; each side expresses the same or similar concepts in different terms. In such cases, the returned search results, if any, may include fewer quality results than actually are available. Consequently, it is often difficult for users to find all the information they need even when the relevant content exists. 
     One example of this situation may occur when a user searches for information within a specialized set of content (e.g., content accessible through a particular website or websites, a particular network, a particular portal, etc.) using terms that appear infrequently in the set of content being searched. For instance, a user may search for information via a medical website within specialized content produced by and intended for medical practitioners and researchers. However, because users of the website may not be medically trained, their search queries may not use many of the terms commonly found in medical articles pertaining to the relevant subject matter. Accordingly, only a few of the terms in user-provided search queries, if any, may appear in the content accessible through the website and many potentially relevant items may be missed. Another example is when users try to search for information in customer support content. Users may not be technically savvy, but yet need to use specific technical terms in order to find the content that will be helpful to them. Many other examples will be apparent to those skilled in the art. 
     Some of the above-mentioned shortcomings of conventional search methods may be addressed by using a secondary or “reference” set of content to improve the quality of search results being returned to users that wish to search a primary, or “target,” set of content. The primary set of content may be any suitable set of content and, for example, may be content accessible via a particular website (e.g., an e-commerce website, a website of a business, a website providing access to one or more databases, etc.). A secondary or reference set of content may be any suitable set of content and, for example, may be content in any information repository (e.g., Wikipedia, WordNet, etc.), database, or content-provisioning source. Though it should be recognized that these are only examples and that the target set of content and the reference set of content may be any suitable sets of content, as aspects of the present invention are not limited in this respect. 
     By way of illustration, in the above example, a reference domain comprising information about diseases commonly known in the public sphere may help to relate terms in users&#39; search queries in a medical website to terms in content accessible through that website. Indeed, it may be easier to relate a user&#39;s search query, such as “Flu Virus,” to content accessible through the medical website, which may refer to viral diseases only by using official classifications for the associated virus, if the reference set of content includes information that identifies “Orthomyxoviridae” as a family of influenza viruses and that influenza is commonly known as the “flu.” Simply put, the reference set of content may serve as a type of “middle-layer” or a “translation or interpretation medium” to aid in translating terms appearing in search queries to terms appearing in the target set of content being searched. 
     Semantic processing techniques may be employed in order to use content in a reference set of content to improve the quality of search results being returned to users that wish to search a target set of content. Accordingly, in some embodiments, a reference knowledge representation as well as a target knowledge representation may be employed. The reference (target) knowledge representation may be any suitable type of knowledge representation, such as a semantic network, and may represent knowledge associated with content in a reference (target) set of content. The reference (target) knowledge representation may be constructed in any suitable way and, for example, may be constructed based at least in part on content in the reference (target) set of content. 
     In some embodiments, the reference and target knowledge representations may be merged to create a merged knowledge representation and one or more terms associated with a user&#39;s search query (and, optionally, terms appearing in the user context information associated with the user) may be used to identify or synthesize one or more concepts in the merged knowledge representation that are semantically relevant to the term(s) associated with the user&#39;s search query and, optionally, terms appearing in the user context information associated with the user. In turn, the obtained concepts may be used to augment the user&#39;s search query with terms associated with the obtained concepts prior to conducting the search. Accordingly, concepts obtained based at least in part on the reference knowledge representation may be used to improve the quality of search results returned in response to users&#39; search queries for content in a target set of content. 
     It should be appreciated that the various aspects of the present invention described herein may be implemented in any of numerous ways, and are not limited to any particular implementation technique. Examples of specific implementations are described below for illustrative purposes only, but aspects of the invention described herein are not limited to these illustrative implementations. Additionally, unless it clearly appears otherwise from the particular context, it is intended that the various features and steps described herein may be combined in ways other than the specific example embodiments depicted and that such other combinations are within the scope of the disclosure and are contemplated as inventive. 
       FIG. 1  is a flow chart of an illustrative process  100  for providing a user with digital content selected from a large set of digital content based on a knowledge representation that may be used in some embodiments. The process of  FIG. 1  begins at act  102 , where user context information associated with one or more users may be obtained. As described in greater detail below, user context information may be any suitable information associated with the user(s) and/or provided by the user(s).The manner in which user context information is obtained is also described in greater detail below. 
     Process  100  then continues to act  104 , where an active concept representing at least a portion of the user-context information may be identified in a knowledge representation. The knowledge representation may be any suitable knowledge representation and, in some embodiments, may be a user-specific knowledge representation associated with the user(s). Though, it should be recognized that the knowledge representation is not limited to being a user-specific knowledge representation and may be any other knowledge representation available to process  100 . In some embodiments, as part of act  104 , an active concept representing the user context information may be generated, for subsequent use in constructing a user-specific knowledge representation comprising the active concept. 
     Process  100  then continues to act  106 , where one or more concepts semantically relevant to the active concept may be obtained by using the knowledge representation comprising the active concept. (Example relevance measures are discussed below.) Process  100  then continues to act  108 , where one or more of the obtained concept(s) may be selected. The concept(s) may be selected based at least in part on a score that one or more of the concept(s) may be assigned by using a relevance measure. Process  100  then proceeds to act  110 , where content may be provided to the one or more users based at least in part on the active concept, identified or generated in act  104 , and the concept(s) selected in act  108 . Such content may be selected from a large set of content by using the active concept and the concept(s) selected in act  108 . Each of the acts of the process of  FIG. 1  may be performed in any of a variety of ways, and some examples of the ways in which these acts may be performed in various embodiments are described in greater detail below. 
     Process  100  and any of its variants may be implemented using hardware, software or any suitable combination thereof. When implemented in software, the software may execute on any suitable processor or collection of processors, whether stand-alone or networked. The software may be stored as processor-executable instructions and configuration parameters; such software may be stored on one or more non-transitory, tangible computer-readable storage media. 
     Software implementing process  100  may be organized in any suitable manner. For example, it may be organized as a software system comprising one or more software modules such that each software module may perform at least a part of one or more acts of process  100 . Though, in some embodiments, one or more software modules of such a software system may perform functions not related to acts of process  100 , as aspects of the present invention are not limited in this respect. 
     I. Obtaining User Context Information 
     As discussed above, at act  102  of process  100 , user context information associated with one or more users may be obtained. User context information may comprise any information that may be used to identify what information the user(s) may be seeking and/or may be interested in. User context information may also comprise information that may be used to develop a model of the user(s) that may be subsequently used to provide those user(s) with information. As such, user context information may include, but is not limited to, any suitable information related to the user(s) that may be collected from any available sources and/or any suitable information directly provided by the user(s). 
     In some embodiments, information related to a user may be any suitable information about the user. For example, information related to a user may comprise demographic information (e.g., gender, age group, education level, etc.) associated with the user. As another example, information related to a user may comprise details of the user&#39;s Internet browsing history. Such information may comprise a list of one or more websites that the user may have browsed, the time of any such browsing, and/or the place (i.e., geographic location) from where any such browsing occurred. The user&#39;s browsing history may further comprise information that the user searched for and any associated browsing information including, but not limited to, the search results the user obtained in response to any such searches. 
     As another example, information related to a user may comprise any information that the user has provided via any user interface on the user&#39;s computing device or on one or more websites that the user may have browsed. For instance, information related to a user may comprise any information associated with the user on any website such as a social networking website, job posting website, a blog, a discussion thread, etc. Such information may include, but is not limited to, the user&#39;s profile on the website, any information associated with multimedia (e.g., images, videos, etc.) corresponding to the user&#39;s profile, and any other information entered by the user on the website. As yet another example, information related to a user may comprise consumer interaction information as described in U.S. patent application Ser. No. 12/555,293, filed Sep. 8, 2009, and entitled “Synthesizing Messaging Using Content Provided by Consumers,” which is incorporated herein by reference. 
     In some embodiments, information related to a user may comprise geo-spatial information. For instance, the geo-spatial information may comprise the current location of the user and/or a computing device of the user (e.g., user&#39;s home, library in user&#39;s hometown, user&#39;s work place, a place to which the user has traveled, and/or the geographical location of the user&#39;s device as determined by the user&#39;s Internet IP address, etc.). Geo-spatial information may include an association between information about the location of the user&#39;s computing device and any content that the user was searching or viewing when the user&#39;s computing device was at or near that location. In some embodiments, information related to a user may comprise temporal information. For example, the temporal information may comprise the time during which a user was querying or viewing specific content on a computing device. The time may be specified at any suitable scale such as on the scale of years, seasons, months, weeks, days, hours, minutes, seconds, etc. 
     Additionally or alternatively, user context information associated with one or more users may comprise information provided by the user(s). Such information may be any suitable information indicative of what information the user(s) may be interested in. For example, user context information may comprise one or more user search queries input by a user into a search engine (e.g., an Internet search engine, a search engine adapted for searching a particular domain such as a corporate intranet, etc.). As another example, user context information may comprise one or more user-specified indicators of the type of information the user may be interested in. A user may provide the indicator(s) in any of numerous ways. The user may type in or speak an indication of his preferences, select one or more options provided by a website or an application (e.g., select an item from a dropdown menu, check a box, etc.), highlight or otherwise select a portion of the content of interest to the user on a website or in an application, and/or in any other suitable manner. For example, the user may select one or more options on a website to indicate that he wishes to receive news updates related to a certain topic or topics, advertisements relating to one or more types of product(s), information about updates on any of numerous types of websites, newsletters, e-mail digests, etc. 
     The user context information may be obtained, in act  102 , in any of a variety of possible ways. For example, in some embodiments, the user context information may be provided from a user&#39;s client computer to one or more server computers that execute software code that performs process  100 . That is, for example, as shown in  FIG. 2 , a user may operate a client computer  202  that executes an application program  204 . Application program  204  may send user context information  206  (e.g., a search query entered by the user into application program  204 ) to server computer  208 , which may be a computer that performs process  100 . Thus, server  208  may receive user context information  206  from application program  204  executing on client  202 . 
     Application program  204  may be any of a variety of types of application programs that are capable of, directly or indirectly, sending information to and receiving information from server  208 . For example, in some embodiments, application program  204  may be an Internet or WWW browser, an instant messaging client, or any other suitable application. 
     In the example of  FIG. 2 , application program  204  is shown as sending the user context information directly to server  208 . It should be recognized that this is a simplified representation of how the user context information may be sent from client  202  to server  208 , and that the user context information need not be sent directly from client  202  to server  208 . For example, in some embodiments, the user&#39;s search query may be sent to server  208  via a network. The network may be any suitable type of network such as a LAN, WAN, the Internet, or a combination of networks. 
     It should also be recognized that receiving user context information from a user&#39;s client computer is not a limiting aspect of the present invention as user context information may be obtained in any other suitable way as part of act  102  of process  100 . For example, user context information may be obtained, actively by requesting and/or passively by receiving, from any source with, or with access to, user context information associated with one or more users. 
     II. Identifying or Generating Active Concept Representing User Context Information 
     As discussed above, at act  104  of process  100 , an active concept, representing at least a portion of the user-context information obtained during act  102 , may be either identified in a knowledge representation, which may be a user-specific knowledge representation or any other suitable knowledge representation, or generated and used to construct a user-specific knowledge representation comprising the active concept. Any of a variety of possible techniques may be used to identify or generate an active concept representing user context information. An example of one such technique that may be used in some embodiments is illustrated in process  300  of  FIG. 3 . 
     Process  300  begins at act  301 , where a relevant portion of the user context information may be identified. As previously discussed, user context information may comprise any of numerous types of information including, but not limited to, information about a user (e.g., profile of the user on a website, the user&#39;s browsing history, etc.) and information provided by a user (e.g., a search query). Accordingly, various portions of the user context information may be used in different scenarios. For example, when a user is searching for information, a relevant portion of the user context information may comprise a user&#39;s search query, but also may comprise additional information that may be helpful in searching for the information that the user seeks (e.g., the user&#39;s current location, the user&#39;s browsing history, etc.). As another example, when presenting a user with one or more advertisements, a relevant portion of the user context information may comprise information indicative of one or more products that the user may have interest in. As another example, when providing a user with news articles (or any other suitable type of content), a relevant portion of the user context information may comprise information indicative of the user&#39;s interests. The relevant portion of the user context information obtained (e.g., in act  102 ) may be identified in any suitable way as the manner in which the relevant portion of the user context information is identified is not a limitation of aspects of the present invention. It should be also recognized that, in some instances, the relevant portion of the user context information may comprise a subset of the user context information, but, in other embodiments, the relevant portion may comprise all of the user context information, as aspects of the present invention are not limited in this respect. 
     The relevant portion of the user context information, identified in act  301 , may be represented in any of numerous ways. For example, in some embodiments, the relevant portion of user context information may be represented via one or more alphanumeric strings. An alphanumeric string may comprise any suitable number of characters (including spaces), words, numbers, and/or any of numerous other symbols. An alphanumeric string may, for example, represent a user search query and/or any suitable information indicative of what information the user may be interested in. Though, it should be recognized that any of numerous other data structures may be used to represent user context information and/or any portion thereof. 
     Next, process  300  proceeds to decision block  302 , where it is determined whether the relevant portion of the user context information associated with a particular user matches a concept in a knowledge representation. Any suitable knowledge representation may be used. In some instances, a user-specific knowledge representation associated with the user or a group of users that includes the user may be used. However, any other suitable knowledge representation may be used and, for example, a knowledge representation not adapted to any particular user or users may be employed. 
     In some embodiments, the knowledge representation used may be a semantic network. Though, in other embodiments, any of other numerous types of knowledge representations may be employed (e.g., a non-graphical knowledge representation). The knowledge representation may be constructed and/or obtained in any suitable way, as the manner in which the knowledge representation is constructed and/or obtained is not a limitation of aspects of the described methods and systems. 
     Regardless of which knowledge representation is used in decision block  302 , the determination of whether the relevant portion of the user context information matches a concept in the knowledge representation may be made in any suitable way. In some embodiments, the relevant portion of the user context information may be compared with a concept identifier. For example, when the relevant portion of the user context information is represented by an alphanumeric string, the alphanumeric string may be compared with a string identifying the concept (sometimes referred to as a “concept label”) to determine whether or not there is a match. The match may be an exact match between the strings, or a substantially exact match in which all words, with the exception of a particular set of words (e.g., words such as “and,” “the,” “of,” etc.), must be matched. Moreover, in some embodiments, the order of words in the strings may be ignored. For instance, it may be determined that the string “The Board of Directors,” matches the concept label “Board Directors” as well as the concept label “Directors Board.” 
     If it is determined, in decision block  302 , that the relevant portion of the user context information matches a concept in the knowledge representation, process  300  proceeds to decision block  304 , where it is determined whether there are multiple concepts in the knowledge representation matching the relevant portion. For example, the selected portion of the user context information may be an alphanumeric string “bark” indicating that the user may be interested in information about “bark.” However, it may not be clear whether the user is interested in information about the bark of a dog or the bark of a tree; there may be concepts associated to each such concept in the knowledge representation. 
     If it is determined, in decision block  304 , that there is only one concept, in the knowledge representation matching the relevant portion of the user context information, the one concept is identified as the active concept and process  300  proceeds via the NO branch to act  320  where the active process is returned for subsequent processing, for example, as described in greater detail below with reference to acts  106 - 110  of process  100 . 
     On the other hand, if it is determined that there are multiple concepts in the knowledge representation matching the relevant portion of the user context information, process  300  continues via the YES branch to acts  306 - 308 , where one of the matching concepts may be selected as the active concept. This may be done in any suitable way. In some embodiments, one of the multiple matching concepts may be selected by using a disambiguation process. 
     Any suitable disambiguation process may be employed to identify an active concept among the multiple concepts matching the relevant portion of the user context information. Such a disambiguation process may comprise using one or more disambiguation terms to identify the active concept among the multiple concepts such that the identified active concept is likely to represent information that the user may be interested in. The disambiguation process may comprise generating a set of candidate disambiguation terms and selecting one or more candidate disambiguation terms to use for identifying the active concept. For example, a set of candidate disambiguation terms, including the terms “dog” and “tree,” may be generated. Subsequent selection of the disambiguation term “dog”, which may be performed either automatically or based at least in part on user input, may indicate that the user is interested in information about “dog barking.” As such, the selected disambiguation terms may be used for semantically disambiguating among the multiple concepts identified in act  304  to identify the active concept. 
     Accordingly, in act  306 , a set of candidate disambiguation terms may be generated. This may be done in any suitable way. For example, the set of candidate disambiguation terms may comprise one or more keywords, morphemes, and/or any other suitable knowledge representation entities of one or more concepts among the multiple concepts matching the relevant portion of the user context information. Additionally, the set of candidate disambiguation terms may comprise one or more keywords, morphemes, and/or any other suitable KR entities of any concepts connected, within a predetermined degree of separation in the semantic network, to a concept among the multiple concepts. Any suitable degree of separation (e.g., one, two, three, four, five, etc.) may be used. In some embodiments, the set of candidate disambiguation terms may not comprise any of the terms in the relevant portion of the user context information, though in other embodiments, the set of candidate disambiguation terms may comprise one or more terms in the relevant portion of the user context information. 
     Next, process  300  proceeds to act  308 , where one or more of the candidate disambiguation terms may be selected. The selection may be performed in any suitable way and may be performed automatically and/or may involve obtaining one or more disambiguation terms based on user input. For example, in some embodiments, one or more candidate disambiguation terms may be provided to the user, such that the user may select those terms that are indicative of what the user is interested in. The candidate disambiguation terms may be provided to the user in any of a variety of possible ways. For example, in some embodiments, the terms may be provided from server  208  (i.e., the computer that performs process  100 ) to the application program  204  on client  202  from which the user context information may have been obtained. In embodiments in which application program  204  is an intranet or WWW browser, the terms may be provided in the form of a web page. As such, the user may select one or more terms to indicate the type of information that the user may be interested in. 
     Regardless of the manner in which one or more candidate disambiguation terms may be provided to a user, user input comprising a selection of one or more disambiguation terms may be received as part of act  308  of process  300 . For example, application program  204  that received the set of candidate disambiguation terms generated in act  306  may accept input from the user selecting one or more of the terms, and may send an indication of the user-selected term(s) to the server executing process  100 . 
     In some embodiments, one or more disambiguation terms may be selected automatically from the set of candidate disambiguation terms, without requiring any user input. For example, one or more terms from the set of candidate disambiguation terms, generated in act  306 , may be selected based on user context information (e.g., the user&#39;s browsing history, online profile, user selected preferences, or any other type of user context information described earlier). Consider, for example, a situation in which a user is searching for “bark,” but that it is clear from the user&#39;s browsing history that the user has shown interest in various information about dogs. In this case, it is likely that the user is searching for information about a “dog bark” rather than “tree bark.” Accordingly, the user context information may be used to select the term “dog” from the set of candidate disambiguation terms {“dog” and “tree”}. As another example, the user&#39;s online profile on a social networking website may indicate that the user is an avid botanist (or geo-spatial information associated with the user indicates that the user is located in a rainforest), in which case it is likely that the user is searching for information about “tree bark” rather than “dog bark.” Though it should be recognized that the abovedescribed techniques for selecting disambiguation terms are merely illustrative as the disambiguation terms may be selected in any other suitable manner. 
     Regardless of the manner in which one or more disambiguation terms may be obtained, in act  308 , the obtained terms may be used to identify an active concept among the multiple concepts matching the relevant portion of the user context information. Accordingly, the identified active concept may represent information in which one or more users may be interested. After the active concept is identified, in act  308 , process  300  proceeds to act  320  where the active process is returned for subsequent processing and process  300  completes. 
     Consider, again, decision block  302  of process  300 . If it is determined in decision block  302  that the relevant portion of the user context information does not match any concept in the knowledge representation (the NO output branch), process  300  proceeds to act  310 , where the relevant portion of the user context information may be decomposed into one or more knowledge representation entities. For example, the relevant portion of the user context information may be decomposed into individual concepts, keywords, and/or morphemes. This may be done in any suitable way. For example, when the portion of the user context information is represented by an alphanumeric string, the string may be tokenized or separated into more elemental knowledge representation entities. Stop words such as “the” and “and” may be filtered out or ignored. For example, if the alphanumeric string is a user&#39;s search query “The BP Board of Directors,” the query may be tokenized into the following entities: “Board of Directors,” “BP Board,” “BP Directors,” “BP”, “Board,” and “Directors.” It should be recognized that many other techniques may be applied to separating the relevant portion of the user context information into knowledge representation entities including the semantic analysis methods described in U.S. patent application Ser. No. 13/165,423, filed Jun. 21, 2011, and titled “Systems and Methods for Analyzing and Synthesizing Complex Knowledge Representations,” which is incorporated herein by reference. 
     Process  300  continues to act  312 , where concepts in the knowledge representation that cover the KR entities, which were derived in act  310 , are identified. This may be done in any suitable way and, for example, may be done by comparing each of the KR entities with concepts in the KR to see if there is a match. In some embodiments, a string associated with a KR entity may be compared with labels of concepts in the KR. For example, consider semantic network  401  shown in  FIG. 4A  comprising concepts  402  and  406  labeled “Board of Directors” and “Board,” respectively. Concepts  402  and  406  are connected by a “defined-by” edge  404 . Though not explicitly shown, the node associated with the concept labeled “Board of Directors” may also be connected via a “defined-by” edge to a node associated with the concept labeled “Director.” Accordingly, nodes existing in semantic network  401  cover KR entities “Board of Directors,” “Directors,” and “Board.” Note that these KR entities were derived from the alphanumeric string “BP Board of Directors” in act  310  of process  300 . Note that semantic network  401  does not include a concept with the label “BP Board of Directors.” 
     Process  300  next continues to acts  314 - 318 , where an active concept corresponding to the relevant portion of the user context information may be generated and, subsequently, used to construct a user-specific knowledge representation comprising the active concept. First, in act  314 , an active concept associated with the relevant portion of the user context information may be generated. This may be done in any suitable way. For example, a new node may be added to the knowledge representation and may be associated with the relevant portion of the user context information. As such, the node may be assigned an identifier (i.e., a concept label) comprising the relevant portion of the user context information. For example, as shown in  FIG. 4B , node  408  associated with the generated active concept and labeled “BP Board of Directors” was added to semantic network  401  to form semantic network  403 . In this and other diagrams of semantic networks, the node corresponding to an active concept may be indicated by a rectangle. 
     Next, as part of act  316 , the new node may be connected by one or more new edges to one or more concepts already present in the knowledge representation. The new node, representing the generated active concept, may be connected to any suitable concepts in the knowledge representation and, for example, may be connected to one or more concepts in the knowledge representation that cover the knowledge representation entities derived from the relevant portion of the user context information. Thus, in the “BP Board of Directors” example, node  408  may be connected to the node associated with the concept “Board of Directors,” to the node associated with the concept “Board,” and/or to the node associated with the concept “Directors.” 
     In some embodiments, the new node may be connected to nodes associated with the most complex concepts that cover the KR entities derived in act  310 . Complexity of a concept may be defined in any of numerous ways. For example, complexity of a concept may be indicative of the number of other concepts that are “defined-by” the concept; the greater the number of concepts “defined-by” the concept, the greater its complexity. Thus, complexity of a concept may be proportional to the number of outgoing “defined-by” edges from the node corresponding to that concept. In semantic network  401 , for example, the concept “Board of Directors” has a greater complexity than the concept “Board.” As another example, complexity of a concept may be indicative of the number of words in the label of the concept; the greater the number of words, the greater its complexity. Thus, complexity of a concept may be proportional to the number of words in the concept label. In this case, the concept “Board of Directors” also has a greater complexity than the concept “Board.” Accordingly, node  408 , associated with the concept “BP Board of Directors,” is connected, in semantic network  405 , by a new “defined-by” edge  410  to node  402 , corresponding to the “Board of Directors” concept. 
     Finally, in act  318 , the knowledge representation may be further augmented such that the knowledge representation includes concepts that may cover all of the KR entities derived from the relevant portion of the user context information in act  310 . To this end, a new node may be added to the knowledge representation for each KR entity derived in act  310  but not covered by a concept already in the knowledge representation. Each such new node may be connected to one or more concepts existing in the knowledge representation and, for example, may be connected via a “defined-by” edge to the concept associated with the generated active concept. For example, the keyword “BP” was derived from the new “BP Board of Directors” concept, but is not covered by any of the concepts in semantic networks  401  or  403 . Thus, as shown in  FIG. 4C , node  416  associated with the concept “BP” may be added to the knowledge representation in act  318  and may be connected to node  408 , associated with the active concept, via a “defined-by” edge  414 . 
     Thus, a new user-specific knowledge representation is created after acts  314 - 318  have been executed. The created knowledge representation is user-specific because it comprises one or more concepts derived from user context information associated with one or more users and the knowledge representation used in act  302 . In the examples of  FIGS. 4A-4C , semantic network  405  was created by incorporating two concepts (i.e., “BP” and “BP Board of Directors” obtained from user context information) into semantic network  401 . Though, it should be recognized that the examples of  FIGS. 4A-4C  are merely illustrative and are not limiting on aspects of the present invention. Next, process  300  continues to act  320 , where the active concept generated in acts  314 - 318  may be provided for subsequent processing, and after act  320 , process  300  completes. 
     It should be appreciated that after the user-specific knowledge representation is created, it may be stored such that it may be subsequently used in any processing associated with the one or more users. For example, the user-specific knowledge representation may be used and/or updated anytime processes  100  or  300  may be executed in connection with the user(s). The user-specific knowledge representation may be stored in any suitable way and, for example, may be stored using one or more non-transitory, tangible computer-readable storage media of any suitable type. 
     III. Identify Concepts Relevant to Active Concept 
     As discussed above, at act  106  of process  100 , one or more concepts relevant to the active concept may be obtained by using a knowledge representation comprising the active concept. The knowledge representation may be any suitable knowledge representation and, in some instances, may be a user-specific knowledge representation associated with the user(s) whose context information was obtained in act  102  of process  100 . The active concept may be any suitable concept in the knowledge representation and may be identified based at least in part on the user context information, for instance, by using process  300 , or in any other suitable way. 
     In some embodiments, one or more concepts relevant to the active concept may be obtained based at least in part on the structure of the knowledge representation comprising the active concept. For example, when the knowledge representation is a semantic network, one or more concepts relevant to the active concept may be obtained based at least in part on the structure of the graph that represents the semantic network. Any of numerous aspects of the graph structure may be used including, but not limited to, the directionality of the edges representing semantic relationships between concepts and whether the semantic relationships are “defined-by” relationships or “is-a” relationships. Additionally or alternatively, the structure of the graph may be used to synthesize one or more new concepts, not initially in the semantic network, that may be relevant to the active concept. In this case, any of the synthesized concepts may be used to augment the semantic network. 
     Any of numerous techniques for obtaining concepts relevant to the active concept based on the graph structure of the semantic network comprising the active concept may be used in act  106  of process  100 . In some embodiments, concepts relevant to the active concept may be obtained by performing one or more types of operations with respect to the graph structure of the semantic network. Three such operations, namely: (1) retrieval, (2) addition, and (3) substitution, are described in greater detail below. These three operations are merely illustrative, however, and any other suitable operations for identifying concepts relevant to the active concept, based at least in part on the graph structure of the semantic network, may be used. For brevity, in the description of the operations that follows, no explicit distinction is made between a node in a graph used to represent a concept and the concept itself. Thus, an edge between two concepts corresponds to an edge between the nodes in the semantic graph used to represent those two concepts. 
     A retrieval operation may be used to identify concepts in the semantic network that are relevant to the active concept. In some embodiments, the retrieval operation may be used to identify concepts that were represented in the semantic network before the active concept was identified and/or generated. Though, in other embodiments, the retrieval operation may be used to identify concepts that were added to the semantic network when the active concept was generated (e.g., in act  318  of process  300 ). 
     In some embodiments, the retrieval operation may identify a concept that is connected by one or more edges, of any suitable type and/or direction, to the active concept as a concept relevant to the active concept. For example, the retrieval operation may identify a concept that is connected by one or more “is-a” edges to the active concept as a concept relevant to the active concept. As a specific example, the retrieval operation may identify a concept that has outgoing “is-a” edge towards the active concept or a concept that has an incoming “is-a” edge from the active concept as a concept relevant to the active concept. 
     A simple example of a retrieval operation is illustrated in  FIG. 5A , which shows a semantic network comprising the active concept “press” (that the concept “press” is active is indicated here by a rectangle) and another concept “push press.” The concept “push press” is connected to the active concept via an outgoing “is-a” relationship. Accordingly, a retrieval operation may be used to identify the concept “push press” as a concept relevant to the active concept. Note that in  FIGS. 5A-5H , the concepts identified as concepts relevant to the active concept are indicated by a diamond. 
     In contrast to the retrieval operation, which may be used to obtain concepts relevant to the active concept among the concepts already in the semantic network, the addition and substitution operations described below may be used to obtain concepts relevant to the active concept by synthesizing new concepts based at least in part on the active concept and on the concepts in the semantic network. Note that in  FIGS. 5B-5H , concepts added to the active concept to synthesize a new concept are indicated by a hexagon. 
     An addition operation may synthesize a new concept by using the active concept and at least one other concept in the semantic network, and return the new concept as a concept relevant to the active concept. The new concept may be synthesized using any of numerous techniques including at least: (1) attribute co-definition, (2) analogy-by-parent, (3) analogy-by-sibling, (4) attribute commonality or any suitable combination thereof. 
     In some embodiments, an addition operation may be used to synthesize a new concept by using the attribute co-definition technique. A first concept in a semantic network is an attribute of a second concept in the semantic network if the first concept defines the second concept. This may be ascertained from the graph representing the semantic network if there is an outgoing “defined-by” edge from the second concept to the first concept. For example, as shown in  FIG. 5B , the concepts “bench,” “press,” and “sets” are attributes of the concept “bench press sets,” and the concepts “press” and “sets” are attributes of the concept “press sets.” If the active concept is an attribute of (i.e., is connected via an outgoing “defined by” edge to) a first concept, and the first concept has one or more other concepts as an attribute, it may be said that the active concept and the other concept(s) co-define the first concept. For example, in  FIG. 5B , “press” is the active concept and, the concepts “press,” “bench,” and “sets” co-define the concept “bench press sets.” 
     In the attribute co-definition technique, a new concept may be synthesized by combining the active concept with any of the other concepts co-defining a concept with the active concept. For example, as shown in  FIG. 5B , the concept “press sets” may be synthesized by combining “press” and “sets.” As another example (not shown in  FIG. 5B ), the concept “bench press” may be synthesized by combining “press” and “bench.” 
     In some embodiments, an addition operation may be used to synthesize a new concept by using the analogy-by-parent technique. In a semantic network, a first concept with an outgoing “is-a” edge to a second concept may be considered as a child concept of the second concept. Stated differently, the second concept may be considered to be a parent concept of the first concept. For example, in  FIG. 5C , the concept “seat” is a parent concept of the active concept “recliner.” The analogy-by-parent technique is motivated by the idea that an attribute that co-defines a concept with a parent of the active concept may be relevant to the active concept. Stated more plainly, something relevant to the parent may be relevant to the child. 
     Accordingly, in the analogy-by-parent technique, a new concept may be synthesized by using the active concept and any second concept that, together with the parent of the active concept, co-defines (or partially co-defines) a third concept. For example, in  FIG. 5C , the concept “seat,” which is the parent concept of “recliner,” and “toilet” together co-define the concept “toilet seat.” Thus, the concept “toilet” co-defines another concept with and, as such, may be deemed relevant to a parent of the active concept. Accordingly, the active concept “recliner” and the concept “toilet” may be used to synthesize a new concept “recliner toilet.” 
     In some embodiments, an addition operation may be used to synthesize a new concept by using the analogy-by-sibling technique. In a semantic network, any two concepts with outgoing “is-a” edges ending at a common (parent) concept may be considered siblings of one another. For example, in  FIG. 5D , the concepts “chair” and “recliner” may be considered as siblings. The analogy-by-parent technique is motivated by the idea that an attribute that co-defines a concept with a sibling of the active concept may be relevant to the active concept. Stated more plainly, something relevant to one sibling may be relevant to another sibling. 
     Accordingly, in the analogy-by-parent technique, a new concept may be synthesized by using the active concept and any second concept that, together with the sibling of the active concept, co-defines (or partially co-defines) a third concept. For example, in  FIG. 5D , the concept “chair,” which is a sibling of the active concept “recliner,” and “massage” together co-define the concept “massage chair.” Thus, the concept “massage” co-defines another concept with and, as such, may be deemed relevant to, the sibling concept “chair.” Accordingly, the active concept “recliner” and the concept “massage” may be used to synthesize a new concept “massage recliner.” 
     It should be recognized that the terms “parents” and “siblings” are used to provide intuition behind some of the above-described operations and that, in some embodiments, such as an atomic knowledge representation model, concepts may not include literal “parent” and “sibling” relationships. The terms “siblings” and “parents” suggest a taxonomy structure in a complex knowledge representation. In contrast, in some embodiments, an atomic knowledge representation model may include only “is-a” and “defined-by” relations. 
     In some embodiments, an addition operation may be used to synthesize a new concept by using the attribute commonality technique. In a semantic network, two concepts may be said to exhibit “attribute commonality” if the concepts share one or more attributes with one another. For example, as shown in  FIG. 5E , the concept “massage chair” and “shiatsu therapy massage chair” share the attributes “massage” and “chair,” and, as such, may be said to exhibit attribute commonality. The attribute commonality technique is motivated by the idea that if a first concept shares one or more attributes with a second concept, then any other attributes of the second concept may be relevant to the first concept. 
     Accordingly, in the attribute commonality technique, a new concept may be synthesized by using the active concept and any attribute of a second concept that shares one or more attributes with the active concept. For example, as shown in  FIG. 5E , the active concept “massage chair” and “shiatsu,” which is an attribute of the concept “shiatsu therapy massage chair” that has attribute commonality with “massage chair,” may be used to synthesize a new concept “shiatsu massage chair.” As another example, not shown in  FIG. 5E , the active concept “massage chair” and “therapy,” may be used to synthesize a new concept “massage therapy chair.” 
     In some embodiments, the attribute commonality technique may comprise generating a new concept by using the active concept and another concept identified by using at least one “is-a” bridge. In a semantic network, two concepts are connected via an “is-a” bridge if they both share outgoing “is-a” edges terminating at a common (parent) concept. For example, in  FIG. 5F , the concepts “yoga” and “weightlifting” are connected via an “is-a” bridge to the concept “exercise.” Also, the concepts “mat” and “bench” are connected via an “is-a” bridge to the concept “furniture.” 
     In the attribute commonality technique, a new concept may be synthesized by using the active concept and a second concept that has an attribute connected to an attribute of the active concept via an “is-a” bridge. In some instances, the new concept may be synthesized by using the active concept and any attribute of the second concept that is not connected to an attribute of the active concept via an “is-a” bridge. For example, as shown in  FIG. 5F , the active concept “yoga mat” has “yoga” and “mat” as its attributes. Each of these attributes is connected with an attribute of the concept “sweat-absorbent weightlifting bench.” Accordingly, the active concept “yoga mat” and the attribute “sweat-absorbent” may be used to synthesize a new concept “sweat-absorbent yoga mat.” 
     The above-described techniques for performing an addition operation comprise synthesizing a new concept, as a concept that may be relevant to the active concept, by combining the active concept with another concept. As a result, the synthesized concept may be a less general or “narrower” concept than the active concept. However, it should be recognized that, concepts relevant to the active concept need not be less general than the active concept and, indeed, may be more general or “broader” concepts than the active concept. 
     Accordingly, in some embodiments, one or more attributes of the active concept may be pruned in order to produce a candidate that is more general than the active concept. This may be done in any suitable way. For instance, attributes may be pruned by performing an “inverse” addition operation, wherein an attribute of the active concept may be removed if, according to any of the above-described techniques, that attribute may be combined with the “broader” concept that results from the pruning. For example, if in the semantic network shown in  FIG. 5E , the concept “shiatsu massage chair” was an active concept and the concept “massage chair” was not in the network, then the concept “massage chair” may be created by pruning the attribute “shiatsu.” Although, in some embodiments, any suitable attribute may be pruned so long as the resulting concept is not in the semantic network. For example, the attribute “massage” may be pruned resulting in the concept “shiatsu chair.” 
     Another operation that may be used to obtain one or more concepts relevant to the active concept is the substitution operation. The substitution operation may be used to synthesize a new concept by replacing one or more attributes of the active concept with another concept, which may be a broader or a narrower concept than the attribute that it replaces. To perform a substitution, either a retrieval or an addition operation may be performed on one or more attributes of the active concept. The concept identified or generated by the retrieval or addition operations, respectively, when performed on a specific attribute of the active concept, may be used to replace the specific attribute to synthesize a new concept. 
     Consider, for example, the semantic network shown in  FIG. 5G  comprising the active concept “strict press” having attributes “strict” and “press.” As previously described with reference to  FIG. 5A , a retrieval operation performed on the attribute “press” may be used to identify the (narrower) concept “push press.” According to the substitution technique, this narrower concept (“push press”) may be combined with any attribute or attributes of the active concept (other than the attribute from which the narrower concept was derived) to synthesize a new concept. In this way, the concept “strict push press” may be synthesized. Similarly, a substitution with retrieval operation may be performed to substitute an attribute of the active concept with a concept that is broader than that attribute. 
       FIG. 5H  illustrates performing a substitution operation by using an addition operation based on the attribute co-definition technique. In this example, applying the attribute co-definition technique to the attribute “press” of the active concept “push press” results in the concept “press sets,” as previously described with reference to  FIG. 5B . Accordingly, the concept “press sets” may be used to replace the attribute “press” in the concept “push press” to synthesize a new concept “push press sets.” 
     In the same vein, substitution operations using any other type of addition operation (e.g., analogy-by-parent, analogy-by-sibling, and attribute commonality) on one or more attributes of the active concept may be used to synthesize one or more concepts relevant to the active concept. 
     IV. Score and Select Identified Concept(s) by using Relevance Measure or Measures 
     After one or more concepts relevant to the active concept are obtained in act  106 , process  100  proceeds to act  108 , where the obtained concepts may be scored and a subset of the concepts may be selected for subsequent use based on the calculated scores. Scores associated to the concepts obtained in act  106  may be calculated in any of numerous ways. In some embodiments, the scores may be obtained by using one or more relevance measures indicative of how relevant a concept to be scored may be to the active concept. A relevance measure may be computed based at least in part on the structure of the graph that represents the semantic network containing the concept to be scored and the active concept. 
     Five measures of relevance are described in greater detail below along with some of their variations, namely: (1) generation certainty, (2) concept productivity, (3) Jaccard (4) statistical coherence, and (5) cosine similarity. Though it should be recognized that these techniques are merely illustrative and that any other suitable techniques for assigning a score to a concept may be used. For example, as described in greater detail below, any of the above techniques may be combined to calculate an integrated score for a concept obtained in act  106 . 
     IV.A Generation Certainty Technique 
     In the generation certainty technique, concept scores may be calculated based at least in part on the structure of the semantic network comprising the concepts. Recall that any of the concepts obtained in act  106  of process  100  may be in the semantic network or may be added to the semantic network after they are synthesized. The generation certainty score calculated for a particular concept may depend on the structure of the semantic network as well as the locations of the particular concept and the active concept within the semantic network. The score may depend on any of numerous aspects of the structure of the semantic network including, but not limited to, the number of edges in a path between the active concept and the particular concept, the number of nodes in a path between the active concept and the particular concept, the types of edges in a path between the active concept and the particular concept, the types of nodes in a path between the active concept and the particular concept, the directionality of the edges in a path between the active concept and the particular concept, any weights associated with edges in a path between the active concept and the particular concept, and any suitable combination thereof. It should be recognized that the structure of a graph representing the semantic network may be such that there are one or multiple paths between the active concept and a concept to be scored. 
     In some embodiments, for example, the generation certainty score computed for a particular concept may be inversely proportional to the number of edges and/or nodes separating the active concept and the particular concept in the semantic graph. Accordingly, the score computed for a concept separated by a large number of edges and/or nodes from the active concept may be lower than the score computed for a concept separated by a smaller number of edges and/or nodes from the active concept. 
     As previously mentioned, in some embodiments, the generation certainty score may be calculated as a function of the weights associated with edges in the semantic network. In particular, the generation certainty score may be calculated as a function of the weights associated with a set of edges in a path between the active concept and the concept being scored. In this case, the generation certainty score may be calculated by taking a product of the weights of the edges in the path from the active concept to the concept being scored. 
     A weight may be assigned to an edge in a semantic network in any of numerous ways. In some embodiments, the weight assigned to an edge may be computed based on a measure of certainty associated with traversing that edge. In turn, the amount of certainty associated with traversing an edge may depend on the type of the edge (i.e., is the edge a “defined-by” edge or an “is-a” edge) and/or on the direction of traversal. In some embodiments, the weight assigned to an edge may be a number between 0 and 1, but in other embodiments the weight may be a number in any other suitable range. 
     For example, traversal of a “defined-by” edge may reduce the certainty associated with traversing the edge by a factor of x, where x may be any suitable number between 0 and 1 and, for example, may be any factor greater than or equal to 0.25, 0.5, 0.75, 0.9, etc. Similarly, traversal of an “is-a” edge may reduce the certainty of traversing the edge by a factor of y, where y may be any suitable number between 0 and 1 and, for example may be any factor greater than or equal to 0.25, 0.5, 0.75, 0.9, etc. In some instances, the factor x may be equal to the factor y, but, in some instances, these factors may be different such that the amount of certainty associated with traversing an edge may depend on the type of edge being traversed. 
     In some embodiments, the amount of certainty associated with traversing an edge may depend on the directionality of the edge and the direction that the edge may be traversed when traversing that edge in a path from one concept to another. For instance, traveling from concept A to concept B (where A “is-a” B such that there is an outgoing “is-a” edge from the node associated with concept A to the node associated with concept B in the semantic network) may reduce the amount of certainty by one factor (e.g., 0.9) while traveling against the direction of the “is-a” edge may reduce certainty by a different factor (e.g., 0.8). 
     In some embodiments, the generation certainty score assigned to a concept may depend on whether that concept was obtained by using a retrieval operation (i.e., the concept was already in the semantic network) or obtained by using an addition or substitution operation (i.e., the concept was synthesized). For example, the generation certainty score may be reduced by a factor (e.g., 0.25) when the concept was synthesized. 
     One illustrative, non-limiting example of computing a generation certainty score is shown in  FIG. 6A . In this case, the generation certainty of the candidate “massage recliner” may be calculated as a product of the weights associated with edges in the path from the active concept “recliner” to the synthesized concept “massage recliner.” As shown in  FIG. 6A , the weight associated with each of the “defined-by” edges along the path is 0.9 and the weight associated with each of the “is-a” edges along the path is 0.75. Further, since the concept “massage recliner” is a synthesized concept, the overall generating certainty score is adjusted by a factor of 0.25. Thus, the generation certainty score, S gc , may be calculated according to: 
     
       
         
           
             
               S 
               gc 
             
             = 
             
               
                 
                   Edge 
                   
                     recliner 
                      
                     
                       - 
                     
                      
                     seat 
                   
                 
                 × 
                 
                   Edge 
                   
                     seat 
                      
                     
                       - 
                     
                      
                     chair 
                   
                 
                 × 
                 
                   Edge 
                   
                     chair 
                      
                     
                       - 
                     
                      
                     massage 
                      
                     
                         
                     
                      
                     chair 
                   
                 
                 × 
                 
                   Edge 
                   
                     massage 
                      
                     
                         
                     
                      
                     chair 
                      
                     
                       - 
                     
                      
                     massage 
                   
                 
                 × 
                 
                   Node 
                   
                     massage 
                      
                     
                         
                     
                      
                     recliner 
                   
                 
               
               = 
               
                 
                   
                     Edge 
                     
                       is 
                        
                       
                         - 
                       
                        
                       a 
                     
                   
                   × 
                   
                     Edge 
                     
                       is 
                        
                       
                         - 
                       
                        
                       a 
                     
                   
                   × 
                   
                     Edge 
                     
                       defined 
                        
                       
                         - 
                       
                        
                       by 
                     
                   
                   × 
                   
                     Edge 
                     
                       defined 
                        
                       
                         - 
                       
                        
                       by 
                     
                   
                   × 
                   
                     Node 
                     synthesized 
                   
                 
                 = 
                 
                   
                     0.9 
                     × 
                     0.9 
                     × 
                     0.75 
                     × 
                     0.75 
                     × 
                     0.25 
                   
                   = 
                   0.1139 
                 
               
             
           
         
       
     
     It should also be recognized that, in some embodiments, the numerical values of the weights associated with the edges in a semantic network may be manually assigned (e.g. assigning the weight of 0.9 to an “is-a” edge and a weight of 0.75 to a “defined-by” edge). Additionally or alternatively, the numerical values of the weights may be based on the statistical coherence measures described below and/or calculated as probabilities using the teachings disclosed in U.S. Provisional Application Ser. No. 61/430,810, filed on Jan. 7, 2011, titled “Probabilistic Approach for Synthesis of a Semantic Network”; U.S. Provisional Application Ser. No. 61/430,836, filed on Jan. 7, 2011, titled “Constructing Knowledge Representations Using Atomic Semantics and Probabilistic Model”; and U.S. Provisional Application Ser. No. 61/532,330, filed on Sep. 8, 2011, titled “Systems and Methods for Incorporating User Models and Preferences into Analysis and Synthesis of Complex Knowledge Representation Models,” all of which are hereby incorporated by reference in their entireties. 
     IV.B Concept Productivity Score 
     In the concept productivity technique, the score of a concept may be calculated based on the number of other concepts in the semantic network that the concept defines. For example, the concept productivity score of a concept may be calculated based on the number of incoming “defined-by” edges that the concept possesses. Some further examples are provided below. 
     For example, the concept productivity score assigned to a concept obtained by using a retrieval operation (e.g., as described with reference to act  106  of process  100 ), may be calculated based on the number of concepts the concept defines. For example, the active concept may be “press”, which may have an incoming “is-a” relationship with the concept “push press” and an incoming “is-a” relationship with “dumbbell press.” As such, both of these concepts may be retrieved as concepts relevant to the active concept in act  106 . However, if the number of concepts defined by the concept “push press” is greater than the number of concepts defined by the concept “dumbbell press”, then the concept “push press” will be assigned a higher concept productivity score than the concept “dumbbell press.” 
     As another example, the concept productivity score assigned to a concept obtained by using an addition operation (e.g., as described with reference to act  106  of process  100 ), may be calculated based on the number of concepts defined by the concept to be added to the active concept in order to generate the synthesized concept. For example, the active concept may be “press” and the concepts synthesized by using one of the addition operations may be “press sets” or “press movements.” If the number of concepts defined by “movements” is greater than the number of concepts defined by “sets,” then the concept “press movements” will be assigned a higher concept productivity score than the concept “press sets.” 
     As another example, the concept productivity score assigned to a concept obtained by using a substitution operation may be calculated based on the number of concepts defined by the concept to be substituted for one of the attributes of the active concept. For example, the active concept may be “push press” and its attribute “press” may be substituted with the concept “press sets” or the concept “press movements.” If the number of concepts defined by the concept “press movements” is greater than the number of concepts defined by the concept “press sets,” then the synthesized concept “push press movements” will be assigned a higher concept productivity score than the synthesized concept “push press sets.” 
     IV.C Jaccard Score 
     In the Jaccard score technique, the score of a particular concept may be calculated based on the number of concepts that fall within a particular degree of separation from the active concept as well as within the same degree of separation from the particular concept. For example, when the degree of separation is one, the Jaccard score of a particular concept may be calculated based on the number of neighbors in common between the particular concept and the active concept. In a semantic network, the neighbor of concept A may be any concept sharing any type of edge with concept A. Since, they share an edge, a neighbor of a concept is within a single degree of separation from the concept. In this case, the larger the number of neighbors in common between an active concept and a concept to be scored, the higher the Jaccard score assigned to that concept. As such, the Jaccard score provides an indication of how interconnected two concepts may be in the semantic network, which, in turn, may be an indication of the relevance of the two concepts. Though, it should be recognized that any degree of separation (e.g., one, two, three, four, five, six, seven, etc.) may be employed. 
     A Jaccard index is a similarity measure for measuring similarity between two sets A and B. In some instances, the Jaccard index may be defined as the size of the intersection of sets A and B divided by the size of the union of the sets A and B, as shown below: 
     
       
         
           
             
               J 
                
               
                 ( 
                 
                   A 
                   , 
                   B 
                 
                 ) 
               
             
             = 
             
               
                 
                    
                   
                     A 
                     ⋂ 
                     B 
                   
                    
                 
                 
                    
                   
                     A 
                     ⋃ 
                     B 
                   
                    
                 
               
               . 
             
           
         
       
     
     The Jaccard index may be applied in our case as follows. Let the set A represent the set of concepts that may be neighbors, or may be within a predetermined number of degrees of separation in the semantic network, from the active concept. Let the set B represent the set of concepts that may be neighbors, or may be within a predetermined number of degrees of separation in the semantic network, from the concept to be scored. Thus, the denominator in the above equation represents the total number of concepts that may be neighbors (or may be within a predetermined number of degrees of separation) of the active concept and/or the concept to be scored while the numerator represents the total number of concepts that are both a neighbor (or may be within a predetermined number of degrees of separation) of the active concept and the concept under evaluation. Accordingly, the Jaccard score of a concept may be computed as the Jaccard index. 
     An example of computing a Jaccard score for a concept obtained in act  106  of process  100  is shown in  FIG. 6B . In this example, the neighborhood of a concept has been selected as comprising concepts within two degrees of separation of the concept. Though, it should be recognized, that a neighborhood associated with any suitable degree of separation may be used. Accordingly, all concepts within two degrees of either the active concept or concept  602 , which is the concept to be scored, have been indicated with diagonal lines, unless they are within two degrees of separation from both the active concept and concept  602 ; such concepts, being within two degrees of both the active concept and concept  602 , are indicated with vertical lines. To compute the Jaccard score, observe that the number of concepts with either diagonal or vertical lines is the number of concepts (25) in the denominator of the Jaccard score. The number of concepts with vertical lines (7) is the number of concepts in the numerator of the Jaccard score. Accordingly, the Jaccard score of concept  602  would be calculated as 7 divided by 25, or 0.38. 
     In some embodiments, such as the embodiment illustrated in  FIG. 6B , neither the active concept nor the concept to be scored are considered neighbors of themselves or of one another. However, in other embodiments, the active concept and/or the concept to be scored may be considered as neighbors of themselves and/or of one another. In the illustration of  FIG. 6B , for example, if the active concept and concept  602  were to be considered neighbors of themselves and of one another, the Jaccard score would be computed as 9 divided by 27, or 0.333. 
     In some embodiments, the Jaccard score may be calculated as the complement of the Jaccard index according to 1-J(A,B) such that the Jaccard score may be indicative of a measure of dissimilarity between concepts A and B. It should be recognized that in this case, concepts with lower scores (rather than higher scores) may be selected in act  108  of process  100 . Further, in this case the concept with a higher Jaccard score would then be considered to possess a weaker relationship with the active concept than a concept with a lower score. 
     In cases when a Jaccard score is being computed for a concept obtained by using a retrieval operation (e.g., as described with reference to act  106 ), the Jaccard score may be obtained by applying the above-described techniques to the retrieved concept. However, when a Jaccard score is being computed for a concept synthesized via an addition operation, the Jaccard score may be obtained by applying the above-described techniques not to the synthesized concept, but rather to the concept that was combined with the active concept to produce the synthesized concept (e.g., the concept “shiatsu” shown in  FIG. 5E ). Similarly, when a Jaccard score is being computed for a concept synthesized via a substitution operation, the Jaccard score may be obtained by applying the above-described techniques not to the synthesized concept, but to the concept that was used to substitute an attribute of the active concept as part of the substitution (e.g., the concept “press sets” shown in  FIG. 5H ). 
     IV.D Statistical Coherence Score 
     Another technique for computing scores for concepts obtained in act  106  is the so-called “statistical coherence” technique where the statistical coherence score assigned to a particular concept will depend on the frequency of co-occurrence of that concept with the active context in one or more text corpora. As such, a concept that co-occurs more frequently with the active concept may be more relevant to the active concept than a concept that co-occurs less frequently with the active concept. 
     Any suitable corpus or corpora may be used to calculate the statistical coherence score for a concept obtained in act  106  of process  100 . For example, the corpora may be from a single source (e.g., all content found at URLs containing the string “wikipedia.org”) or multiple sources. As another example, subject-specific corpora may be used such as corpora containing content about politics, medical articles, sports, etc. Each corpus may be of any suitable type and, for example, may be a text corpus or a corpus containing multiple types of content. 
     Regardless of the number and types of corpora used for calculating coherence scores, in some embodiments, the active concept may be used to select a subset of content in the corpora (e.g., a portion of the documents in a text corpus) to use for calculating statistical coherence scores. This may be done in any suitable way. For example, the active concept may be used to select content relevant to the active concept, which, for example, may be only that content which contains the label of the active concept. 
     In some embodiments, the content used for statistical coherence calculations may be further restricted to that content which contains the active concept and at least one of the concepts in a neighborhood of the active concept in the semantic network. Recall that such a neighborhood may include all concepts, in the semantic network, that are within a predetermined number of degrees of separation (e.g., one, two, three, four, etc.) from the active concept. The additional restriction may be accomplished in any suitable way and, for example, may be achieved by using only that content which contains the label of the active concept and the label of at least one other concept in the neighborhood of the active concept. Restricting the corpora based on the active concept as well as its neighbors may be advantageous in that content that includes the label of the active concept, but is directed towards a distinct meaning, is not considered when calculating a statistical coherence score. 
     For example, if the active concept is “bat” and the concepts found within the active concept&#39;s neighborhood include the concepts “baseball bat,” “club,” “paddle,” and “lumber,” the content used for calculating statistical coherence scores may be limited to content that includes the active concept “bat” and at least one of the neighboring concepts “baseball bat,” “club,” “paddle,” and “lumber.” The inclusion of at least one of these neighbors may increase the likelihood that documents that include the concept “bat,” but are related to the mammal, are avoided when calculating the statistical coherence score. 
     Accordingly, in some embodiments, the statistical coherence score may be computed as a function of the ratio of the number of documents containing both the active concept, at least one concept in a neighborhood of the active concept, and the concept to be scored and the number of documents containing the active concept and the at least one concept in the neighborhood of the active concept. The function may be any suitable function and, for example, may be the identity function or any other suitable monotonically increasing function (e.g., logarithm). When calculated in this manner, the statistical coherence score may reflect the proportion of the total number of documents relevant to the active concept that are also relevant to the concept to be scored. Accordingly, the higher the statistical coherence score for a concept the more likely it may be that this concept is relevant to the active concept. 
     In some embodiments, the statistical coherence score may be computed as a function of the ratio of the number of documents containing the active concept, at least one concept in a neighborhood of the active concept, the concept to be scored, and at least one concept in the neighborhood of the concept to be scored (in the numerator) with the number of documents containing the active concept and at least one concept in a neighborhood of the active concept (in the denominator). Calculating a statistical coherence score in this way may be advantageous in that content that includes the label of the concept to be scored, but is directed towards a distinct meaning, is not considered when calculating a statistical coherence score. 
     For example, the concepts “field game” and “sport” may be neighbors of the candidate “cricket.” Restricting the documents used in computing the statistical coherence score to only the documents that include the concept “cricket” and at least one concept from among “field game” and “sport” may increase the likelihood that documents that include the concept “cricket,” but are related to the insect, are avoided when calculating the statistical coherence score. 
     In some embodiments, the statistical coherence score may be computed by using only a subset of the documents containing the active concept, at least one concept in the neighborhood of the active concept, the concept to be scored, and, optionally at least one concept in the neighborhood of the concept to be scored. In this case, the statistical coherence score may be computed as a function of a so-called term frequency (TF) score of the concept to be scored in one or more documents in the aforementioned subset of documents. 
     In some embodiments, a TF score for a concept to be scored may be calculated for each document in the subset and the statistical coherence score may be calculated as the average or median of the computed TF scores. Alternatively, the statistical coherence score may be calculated as the largest calculated TF score. This may be advantageous in situations when a concept to be scored appears infrequently in a large number of documents within the subset of documents used for calculating the statistical coherence score. 
     In yet another embodiment, the statistical coherence score may be computed as a function of the inverse document frequency (IDF) score, which may be computed as a reciprocal of how frequently a concept to be scored appears within the set of documents used for calculating the statistical coherence score. In yet another embodiment, the statistical coherence score may depend on the product of the term frequency and the inverse document frequency scores. It should be appreciated that, in some embodiments, values calculated in the process of computing the statistical coherence score may be normalized. 
     It should be appreciated that, just as the case may be when computing the Jaccard score, the way in which the statistical coherence score is calculated may depend on whether the concept to be scored was retrieved from the semantic network or, instead, was synthesized during act  106  of process  100 . In the case that the concept to be scored was synthesized by using an addition operation, the statistical coherence score may be obtained by applying the above-described techniques not to the synthesized concept, but rather to the concept that was combined with the active concept to produce the synthesized concept (e.g., the concept “shiatsu” shown in  FIG. 5E ). Similarly, when a statistical coherence score is being computed for a concept synthesized via a substitution operation, the statistical coherence score may be obtained by applying the above-described techniques not to the synthesized concept, but to the concept that was used to substitute an attribute of the active concept as part of the substitution (e.g., the concept “press sets” shown in  FIG. 5H ). 
     IV.E Cosine Similarity Score 
     In the cosine similarity technique, the cosine similarity score of a particular concept may be calculated by using the cosine similarity metric for evaluating semantic proximity between pairs of concepts. To evaluate the cosine similarity metric between two concepts A and B, each of the concepts is mapped to two vectors in Euclidean space of any suitable dimension. The cosine similarity between the two concepts may then be computed as the ratio between the inner product between the two vectors and the product of the magnitudes of the two vectors. This ratio represents the cosine of the angle between the two vectors, giving rise to the name “cosine similarity.” 
     A concept may be mapped to a vector in any suitable way. For example, a concept may be mapped to a vector comprising a coordinate for each of the concept&#39;s attributes, with each coordinate containing a number associated with the attribute. Thus, if concept A has ten attributes, the concept may be mapped to a ten-dimensional vector such that the number in each dimension is associated to the corresponding attribute. The number corresponding to an attribute may be any suitable number and, for example, may be a term frequency (TF) score or a TF-IDF score associated with the attribute. 
     IV.F Integrated Score 
     As previously mentioned, any of the types of scores described above may be combined to form an integrated score that may be assigned to the concepts obtained in act  106  of process  100 . Though, in some embodiments, the scores need not be combined and only one of the aforementioned types of scores may be assigned to each concept obtained in act  106 . 
     In embodiments where one or more types of scores may be combined to form an integrated score, the scores may be combined in any of numerous ways. For example, the scores may be combined by computing a weighted linear combination of the scores to compute the integrated score. The weights used to combine the scores may be any suitable weights and may be increased or decreased to reflect which scores should be weighted more when combining the scores into an integrated score. The scores and/or weights may be normalized in any suitable way prior to be combined into an integrated score. 
     After a score is assigned for the concepts obtained in act  106  of process  100 , one or more of the scored concepts may be selected for subsequent use based on the calculated scores. The score-based selection may be done in any suitable way. In some embodiments, for example, concepts associated with a score above a predetermined threshold may be selected for subsequent use. Alternatively, a predetermined number or percentage of the top-scoring concepts may be selected. Though, it should be recognized that many other ways of utilizing scores to select one or more concepts will be apparent to one skilled in the art. 
     V. Provide Content to User(s) Based on Active Concept and Selected Concept(s) 
     After one or more concepts relevant to the active concept are selected in act  108 , process  100  proceeds to act  110 , where information may be provided to the user(s) associated with the user context information obtained in act  102 , based at least in part on the active concept identified or generated in act  104  and the relevant concept(s) selected in act  108 . To this end, information to present to the user(s) may be selected from among a larger set of information by using the active concept and relevant concept(s) selected in act  108 . Though, it should be recognized that the type of information provided to the user(s) and the manner in which the information may be provided to the user(s) may vary depending on the specific scenario in which the techniques described herein may be applied. 
     As previously mentioned, in some embodiments, user context information obtained in act  102  may comprise information provided by a user that may indicate the type of information that the user may be interested in. For example, the user context information may comprise a user request for information that the user may be seeking. Such a request may be in any suitable form such as a search query or one or more settings indicating that the user wishes to receive news updates related to a certain topic or topics, advertisements relating to one or more types of product(s), information about updates on any of numerous types of websites, newsletters, e-mail digests, etc. Accordingly, in response to the request, the user may be presented with information obtained, from among a large set of content that may be presented to the user, based at least in part on the active concept, which was derived from the user&#39;s request, and the relevant concepts to the active concept that were selected in act  108 . 
     For example, if the user&#39;s request comprised a search query, the active concept and the related concepts, selected in act  108 , may be used to generate one or more search queries to be provided to one or more search services. This may be done in any suitable way. For example, a search query may be constructed from the active concept and any of the selected concepts by using the labels and attributes associated with these concepts. A search query may be formed by joining the concept labels and attributes from the active concepts and any of the selected concepts by using various Boolean operators such as “AND” and “OR.” For example, if the active concept representing a user&#39;s search query is the concept “yoga mat,” described with reference to  FIG. 5F  and the concept “sweat-absorbent yoga mat” is selected in act  108 , a search query “(yoga mat) AND (sweat-absorbent)” may be formed. As another example, if the active concept representing a user&#39;s search query is the concept “recliner,” described with reference to  FIG. 5D  and the concept “massage recliner” is selected in act  108 , a search query “(recliner) OR (massage recliner)” may be formed. Other more complex search queries may be formed and may include keywords associated with multiple selected concepts, any disambiguation terms used to identify the active concept, and/or any other user context information. For example, suppose a user is searching for an Italian restaurant at 10 pm, while renting a car at the airport. The active concept “Italian restaurant” may be used to select relevant concepts such as “Pizza,” “Pasta,” and “Carbs” and, together with geo-spatial information about the user obtained from the user context information, be used to construct a query such as “(Italian Restaurant) OR (Pizza) OR (Pasta) OR (Carbs) AND (New York) AND (Airport) and (OPEN AFTER 10 pm).” 
     These types of complex queries would rarely be composed by users. Such queries create an effective semantic search, even if the content has not been semantically analyzed in advance (e.g., unstructured content), because such a query will match literal terms in the content indexed by the search service that are not necessarily literal terms in the original query. 
     The search service may be any general-purpose search engine. For instance, the search service may be any search engine that may be publicly accessible via the Internet. As another example, the search service may be a search engine accessible via any computer network other than the Internet. Examples of such search engines include search engines used for searching a corporate intranet or any other private network. 
     In response to issuing the one or more search queries to the search service, a set of search results may be received from the search service. The text (or fragments of the text) of the documents or pieces of content in the search results may be compared to the active concept and/or the concept(s) selected in act  108  and the returned search results may be ranked and/or filtered out based on how closely they match these concept definitions. 
     Any of a variety of possible ranking or filtering techniques may be used, as the invention is not limited in this respect. However, such techniques may enable the provisioning of content to users without overwhelming the users with information irrelevant to the users. Search services may provide a number of textual features in their search results: titles, abstracts, descriptions, tags, hyperlinks, etc. These textual features may provide for text analysis as a means to filter the search engine results against the terms provided through concepts selected in act  108 , for example, by comparing the terms against words in the textual features of the search engine results. Whole or partial matches of terms may be used to weight the relevance of the individual results. In some embodiments, the search results returned from the search service may not include the identified pieces of content themselves, but rather may include a list of hyperlinks to these pieces of content along with an excerpt of each piece of content. In such embodiments, rather than retrieving each piece of content using the provided hyperlink, the list of hyperlinks may be filtered and ranked using the associated excerpt, and the excerpt may be semantically annotated. 
     In some embodiments, user context information obtained in act  102  may comprise information related to a user that may indicate the type of information that the user may be interested in. For example, information related to the user may comprise demographic information, the user&#39;s Internet browsing history, any information associated with the user on a website such as a social networking website, geo-spatial information may comprise the current location of the user&#39;s computing, etc. Accordingly, the user may be presented with information obtained at least in part based on the active concept, which was derived from information related to the user, and the selected concepts. 
     For example, a user may be presented with personalized product and service recommendations based on the active concept and the selected concepts. Consequently, the personalized recommendations may reflect one or more of the user&#39;s interests. The personalized recommendations may include promotional content including, but not limited to, advertisements for products and/or services. For example, an active concept, derived from user context information, may indicate that the user is interested in “recliners.” Accordingly, the user may be presented with advertisements related to “recliners” and to “massage recliners,” which is a concept relevant to the active concept “recliners” as described with reference to  FIG. 5D . As such, the user may not be presented with irrelevant promotional content. 
     As another example, a user may use an online information source (or multiple websites) to obtain information that the user may be interested in. The online information source may be any suitable information source and, for example, may be an Internet portal, an Intranet portal, a news website, a social networking website, a micro-blogging service, a blog service, a blog reader, a shopping website, real-time feeds, etc. Each such online information source may be configured to present any of numerous types of information to a user including, but not limited to, news, advertisements, content recommendations, real-time updates (e.g., tweets). As such, when the user uses the online information source, the user may not be overwhelmed with irrelevant content. 
     Accordingly, in some embodiments, the active concept and the selected concepts may be used to rank, prioritize and/or filter the information that may be presented to a user such that the information presented to the user may reflect that user&#39;s interests. This may be done in any suitable way. For example, any of the information that a website may be configured to present to a user may comprise one or more textual features (e.g., tags, text, hyperlinks, descriptions, etc.). These textual features may be compared to any keywords provided through the active concept and concepts selected in act  108 . Whole or partial matches may be used to weight the relevant of the individual terms. 
     VI. Providing a User with Information Based on Multiple Knowledge Representations 
     As previously mentioned, semantic processing techniques may be used to improve the quality of search results being returned to users that wish to search a target set of content. In particular, semantic processing techniques may be employed to improve the quality of search results by using a reference set of content. One set of such techniques is described below with reference to  FIG. 7  that shows an illustrative process  700  for searching content in a target set of content based on a reference set of content. 
     Process  700  begins at act  702 , where a search query from a user may be obtained. The search query may indicate the user&#39;s desire to search for information in a target set of content. As previously mentioned, the target set of content may be any suitable set of content and, for example, may be content accessible via a particular website (e.g., an e-commerce website, a website of a business, a website providing access to one or more databases, an online portal, a corporate Intranet, etc.). In one non-limiting example, described with reference to  FIGS. 8A-8C , a user may wish to search a medical database for information about the “Flu Virus.” In another non-limiting example, described with reference to  FIGS. 9A-9B , a user may wish to search content accessible through a website for information about how a software program, named “BB Messenger” may be used for instant messaging and, as such, may input the search query “BB Messenger Instant Messaging” Though, it should be recognized that these are only illustrative examples and that the target set of content may be any suitable set of a content that may be searched based on the user&#39;s query. 
     The search query may be received in any of a variety of possible ways. For example, in some embodiments, the search query may be provided from a user&#39;s client computer to a server computer that executes software code that performs process  700 . For example, as previously described with reference to  FIG. 2 , a user may operate a client computer  202  that executes an application program  204 . Application program  204  may send a search query entered by the user into application program  204  to server computer  208 , which may be a computer that performs process  700 . 
     Additionally, in some embodiments, user context information associated with the user may be obtained in act  702  of process  700 . Any of numerous types of user context information may be obtained including, but not limited to, any of the types of user context information previously described. The user context information may be obtained in any suitable way and, for example, may be obtained in the same way as the search query may be obtained and/or in any other suitable manner, including any of the previously-described ways for obtaining user context information. 
     Next process  700  continues to act  704 , where a concept representing the search query and, optionally user context information, obtained in act  702  may be identified in a reference knowledge representation. As previously mentioned, the reference knowledge representation may be any suitable type of KR, such as a semantic network, and may represent knowledge associated with content in a reference set of content. The reference set of content may be any suitable set of content and, for example, may be content in an online information repository such as Wikipedia or any other suitable reference corpus or corpora. 
     A concept representing the search query and, optionally, user context information, may be identified in the reference knowledge representation in any suitable way. For instance, an alphanumeric string representing the search query and, optionally, user context information may be compared with one or more concept labels associated with concepts in the reference knowledge representation to determine whether there may be at least a partial match between the alphanumeric string and at least one concept. As before, when determining whether there is a match between any pair of strings being compared, certain words (e.g., “and,” “the,” “of,” etc.) may be ignored. For clarity, we refer to the concept identified in act  704  of process  700 , as concept “R.” 
     One example of how concept R may be identified in the reference knowledge representation is shown in  FIG. 8A , where the user search query “Flu Virus” exactly matches the label of concept  802  in semantic network  801 , which is a reference knowledge representation. Note that although  FIG. 8A  shows only three concepts in semantic network  801 , this is done for clarity of illustration as semantic network  801  may comprise one or more other concepts. Another example of identifying concept R is shown in  FIG. 9A , where the user search query “BB Messenger Instant Messaging” partially matches the label “Instant Messaging” of concept  916  in semantic network  910 , which is a reference knowledge representation derived from content in one or more reference corpora  908  (e.g., Wikipedia, WordNet, etc.). Similar to semantic network  801 , semantic network  910  may comprise one or more concepts not explicitly shown in  FIG. 9A  for the sake of clarity. 
     Process  700  next continues to act  706 , where concepts relevant to concept R, identified in act  704 , may be obtained. This may be done in any suitable way and, in some embodiments, may be done in any of the ways described with respect to act  106  of process  100 . For example, concepts relevant to concept R may be obtained based at least in part on the structure of the reference semantic network comprising the concept R. The structure of the reference semantic network may be used to identify concepts relevant to concept R that may be in the reference semantic network. For example, as illustrated in  FIG. 8A , concept  806  is connected via an “is-a” edge with concept  802  (i.e., concept R) and, as such, may be identified as a concept relevant to concept R in act  706  of process  700 . Additionally or alternatively, the structure of the reference semantic network may be used to synthesize concepts, not initially in the semantic network, that may be relevant to concept R. Any of the synthesized concepts may be used to augment the semantic network. Also, as previously described with reference to act  106  of process  100 , concepts relevant to concept R may be obtained by performing one or more types of operations with respect to the graph structure of the semantic network including the retrieval, addition, and/or substitution operations. 
     Process  700  next continues to act  708 , where a concept representing the search query and, optionally user context information, obtained in act  702  may be identified in a target knowledge representation. As previously mentioned, the target knowledge representation may be any suitable type of KR, such as a semantic network, and may represent knowledge associated with content in a target set of content. The target set of content may be any suitable set of content and, for example, may be content in accessible via a particular website (e.g., an e-commerce website, a website of a business, a website providing access to one or more databases, an online portal, a corporate Intranet, etc.). 
     A concept representing the search query and, optionally, user context information, may be identified in the target semantic network in any suitable way. For example, this concept may be identified in the same way as described with reference to act  704 , where an alphanumeric string representing the search query and, optionally, user context information, may be compared with labels of concepts in the target semantic network to find at least a partial match. Indeed, there may not be an exact match between the alphanumeric string comprising the user&#39;s search query and any concept labels in the target semantic network because, as previously discussed, the search query may include one or more terms that appear infrequently in the target set of content. Since the target semantic network represents knowledge associated with the target set of content, the user&#39;s search query may not correspond, exactly, to a concept in the target semantic network. For clarity, we refer to the concept identified in act  704  of process  700 , as concept “T.” 
     One example of how concept T may be identified in the reference knowledge representation is shown in  FIG. 8B , where the user search query “Flu Virus” partially matches the label of concept  812  (“Virus”) in semantic network  803 , which is a target knowledge representation. Note that although  FIG. 8B  shows only four concepts in semantic network  803 , this is done for clarity of illustration as semantic network  803  may comprise one or more other concepts. Another example of identifying concept T is shown in  FIG. 9A , where the user search query “BB Messenger Instant Messaging” partially matches the label “BB Messenger” of concept  912  in semantic network  906 , which is a target knowledge representation derived from content that the user is attempting to search via the provided search query. Similar to semantic network  803 , semantic network  906  may comprise one or more concepts not explicitly shown in  FIG. 9A  for the sake of clarity. 
     Process  700  next continues to act  708 , where concepts relevant to concept T, identified in act  706 , may be obtained. This may be done in any suitable way and, in some embodiments, may be done in any of the ways described with respect to act  706 . For example, concepts relevant to concept T may be obtained based at least in part on the structure of the target semantic network comprising the concept T. The structure of the target semantic network may be used to identify concepts relevant to concept T that may be in the target semantic network. Additionally or alternatively, the structure of the target semantic network may be used to synthesize concepts, not initially in the semantic network, that may be relevant to concept T. Any of the synthesized concepts may be used to augment the target semantic network. Also, as previously described with reference to act  706 , concepts relevant to concept T may be obtained by performing one or more types of operations with respect to the graph structure of the target semantic network including the retrieval, addition, and/or substitution operations. For example, as illustrated in  FIG. 9A , concept  914  “BB Messenger Buzzer” may be synthesized, via an addition operation, from concept T (“BB Messenger”) and the concept “Buzzer” in the target semantic network. 
     Next, process  700  continues to act  712 , where the reference and the target knowledge representations, each of which may have been augmented with synthesized concepts in acts  706  and  710 , may be combined to create a merged knowledge representation. In turn, the merged knowledge representation may be used to identify concepts semantically relevant to the user&#39;s search query and, optionally, user context information. The merged knowledge representation may be created in any suitable way. In some embodiments, the reference and target knowledge representations may be merged around one or more concepts that these KRs may have in common. For example, as shown in  FIG. 8C , semantic networks  801  and  803  are merged around the common concept “Influenza Virus” to form merged semantic network  805 . As another example, as shown in  FIG. 9B , semantic networks  906  and  910  are merged around the common concept “Social Network” to form semantic network  922 . 
     In some embodiments, a semantic network being merged with another semantic network may be pruned to remove one or more concepts from the semantic network prior to merging such that the one or more pruned concepts are not represented in the merged semantic network. For example, concept  920  (“Advertising) is pruned from semantic network  910  prior to the merging step. Additionally or alternatively, one or more concepts may be pruned from the merged semantic network, after the merging step. Any suitable concept or concepts may be pruned. For example, in some embodiments, concepts deemed not relevant to the user&#39;s search query and, optionally, to the user context information, may be pruned. 
     After a merged knowledge representation is created in act  712 , process  700  continues to act  714 , where concepts relevant to the user&#39;s search query and, optionally, user context information associated with the user, may be obtained using the merged knowledge representation. This may be done in any suitable way and, for example, may be done in accordance with the techniques described with respect to acts  104 - 106  of process  100 . As such, an active concept representing the user&#39;s search query and, optionally, user context information, may be identified in the merged knowledge representation or generated to augment the merged knowledge representation (thereby creating a user-specific KR) using techniques described with reference to act  104  and process  300 . Subsequently, one or more concepts semantically relevant to the active concept may be identified based at least in part on the structure of the merged semantic network using techniques previously described with reference to act  106  of process  100 . 
     Next, process  700  continues to act  716 , where scores are computed for concepts semantically relevant to the active concept, which were obtained in act  714 . The scores may be computed in any suitable way and, for example, may be computed using any of the techniques described with reference to act  108  of process  100 . In using such techniques, scores calculated for concepts obtained in act  714  may depend on the structure of the merged semantic network obtained in act  712 . One or more of the scored concepts may be selected based on the scores in any of the ways previously described with reference to act  108  of process  100 . 
     Next, process  700  continues to acts  718 - 722 , where the concepts selected in act  718  may be used to a construct a search query or queries, the constructed query or queries may be issued to a search service, and the search results may be processed and provided to the user. These acts may be performed using any of the techniques previously described with reference to act  110  of process  100 . For example, a search query may be constructed from the active concept and any of the concepts selected in act  716  by using the labels and attributes associated with these selected concepts. 
     It should be recognized that process  700  is merely illustrative and that any of numerous variations of process  700  may be implemented. For example, in the illustrated embodiment, one or more concepts may have been synthesized before the reference and target semantic networks were merged, in acts  706  and  710 . However, in other embodiments, synthesis of new concepts may be performed only after the merging steps. As another example, process  700  was described relative to two knowledge representations (a reference KR and a target KR). However, in other embodiments, more than one reference knowledge representation may be employed to improve the quality of search results returned to users searching a target set of content. This may be done in any suitable way. For example, process  700  may be adapted to repeat acts  704  and  706  for each knowledge representation so as to identify reference concepts R 1 , R 2 , R 3 , etc. and obtain concepts semantically relevant to these relevant concepts. Then, the merging act would merge multiple reference knowledge representations with the target knowledge representation. 
     VII. Additional Implementation Detail 
     The above-discussed computing devices (e.g., client computer and server shown in  FIGS. 2A and 2B ) may be implemented in any of a variety of ways.  FIG. 10  is a block diagram an illustrative computing device  1000  that may be used to implement any of the above-discussed computing devices. 
     The computing device  1000  may include one or more processors (e.g., microprocessors)  1001  and one or more tangible, non-transitory computer-readable storage media (e.g., memory  1003 ). Memory  1003  may store, in tangible non-transitory computer-readable storage media computer instructions that implement any of the above-described functionality. Processor(s)  1001  may be coupled to memory  1003  and may execute such computer instructions to cause the functionality to be realized and performed, Computing device  1000  may also include a network input/output (I/O) interface  1005  via which the computing device may communicate with other computers (e.g., over a network). In some embodiments, the computing device may also include one or more user I/O interfaces, via which the computer may provide output to and receive input from a user. The user I/O interfaces may include devices such as a keyboard, a mouse, a microphone, a display device (e.g., a monitor or touch screen), speakers, a camera, and/or various other types of I/O devices. 
     The above-described embodiments of the present invention can be implemented in any of numerous ways. For example, the embodiments may be implemented using hardware, software or a combination thereof. When implemented in software, the software code may be embodied as stored program instructions that may be executed on any suitable processor or collection of processors (e.g., a microprocessor or microprocessors), whether provided in a single computer or distributed among multiple computers. 
     It should be appreciated that a computer may be embodied in any of numerous forms, such as a rack-mounted computer, a desktop computer, a laptop computer, or a tablet computer. Additionally, a computer may be embodied in a device not generally regarded as a computer, but with suitable processing capabilities, including a Personal Digital Assistant (PDA), a smart phone, a tablet, a reader, or any other suitable portable or fixed electronic device. 
     Also, a computer may have one or more input and output devices. These devices may be used, among other things, to present a user interface. Examples of output devices that may be used to provide a user interface include printers or display screens for visual presentation of output, and speakers or other sound generating devices for audible presentation of output. Examples of input devices that may be used for a user interface include keyboards, microphones, and pointing devices, such as mice, touch pads, and digitizing tablets. 
     Such computers may be interconnected by one or more networks in any suitable form, including networks such as a local area network (LAN) or a wide area network (WAN), such as an enterprise network, an intelligent network (IN) or the Internet. Such networks may be based on any suitable technology and may operate according to any suitable protocol and may include wireless networks, wired networks, and/or fiber optic networks. 
     The various methods or processes outlined herein may be coded as software that is executable on one or more processors that employ any one of a variety of operating systems or platforms. Additionally, such software may be written using any of numerous suitable programming languages and/or programming or scripting tools, and also may be compiled as executable machine language code or intermediate code that is executed on a virtual machine or a suitable framework. 
     In this respect, various inventive concepts may be embodied as at least one non-transitory tangible computer-readable storage medium (e.g., a computer memory, one or more floppy discs, compact discs, optical discs, magnetic tapes, flash memories, circuit configurations in Field Programmable Gate Arrays or other semiconductor devices, etc.) article(s) encoded with one or more programs that, when executed on one or more computers or other processors, implement the various process embodiments of the present invention. The non-transitory computer-readable medium or media may be transportable, such that the program or programs stored thereon may be loaded onto any suitable computer resource to implement various aspects of the present invention as discussed above. 
     The terms “program” or “software” are used herein in a generic sense to refer to any type of computer code or set of computer-executable instructions that can be employed to program a computer or other processor to implement various aspects of embodiments as discussed above. Additionally, it should be appreciated that according to one aspect, one or more computer programs that when executed perform methods of the present invention need not reside on a single computer or processor, but may be distributed in a modular fashion among different computers or processors to implement various aspects of the present invention. 
     Computer-executable instructions may be in many forms, such as program modules, executed by one or more computers or other devices. Generally, program modules include routines, programs, items, components, data structures, etc. that perform particular tasks or implement particular abstract data types. Typically the functionality of the program modules may be combined or distributed as desired in various embodiments. 
     Also, data structures may be stored in non-transitory tangible computer-readable storage media articles in any suitable form. For simplicity of illustration, data structures may be shown to have fields that are related through location in the data structure. Such relationships may likewise be achieved by assigning storage for the fields with locations in a non-transitory tangible computer-readable medium that convey relationship between the fields. However, any suitable mechanism may be used to establish relationships among information in fields of a data structure, including through the use of pointers, tags or other mechanisms that establish relationships among data elements. 
     Also, various inventive concepts may be embodied as one or more methods, of which multiple examples have been provided (e.g., processes  100 ,  300 , and  700 ). The acts performed as part of the method may be ordered in any suitable way. Accordingly, embodiments may be constructed in which acts are performed in an order different than illustrated, which may include performing some acts simultaneously, even though shown as sequential acts in illustrative embodiments, or vice versa. 
     All definitions, as defined and used herein, should be understood to control over dictionary definitions, definitions in documents incorporated by reference, and/or ordinary meanings of the defined terms. 
     The indefinite articles “a” and “an,” as used herein, unless clearly indicated to the contrary, should be understood to mean “at least one.” 
     As used herein, the phrase “at least one,” in reference to a list of one or more elements, should be understood to mean at least one element selected from any one or more of the elements in the list of elements, but not necessarily including at least one of each and every element specifically listed within the list of elements and not excluding any combinations of elements in the list of elements. This definition also allows that elements may optionally be present other than the elements specifically identified within the list of elements to which the phrase “at least one” refers, whether related or unrelated to those elements specifically identified. Thus, as a non-limiting example, “at least one of A and B” (or, equivalently, “at least one of A or B,” or, equivalently “at least one of A and/or B”) can refer, in one embodiment, to at least one, optionally including more than one, A, with no B present (and optionally including elements other than B); in another embodiment, to at least one, optionally including more than one, B, with no A present (and optionally including elements other than A); in yet another embodiment, to at least one, optionally including more than one, A, and at least one, optionally including more than one, B (and optionally including other elements); etc. 
     The phrase “and/or,” as used herein, should be understood to mean “either or both” of the elements so conjoined, i.e., elements that are conjunctively present in some cases and disjunctively present in other cases. Multiple elements listed with “and/or” should be construed in the same fashion, i.e., “one or more” of the elements so conjoined. Other elements may optionally be present other than the elements specifically identified by the “and/or” clause, whether related or unrelated to those elements specifically identified. Thus, as a non-limiting example, a reference to “A and/or B”, when used in conjunction with open-ended language such as “comprising” can refer, in one embodiment, to A only (optionally including elements other than B); in another embodiment, to B only (optionally including elements other than A); in yet another embodiment, to both A and B (optionally including other elements); etc. 
     As used herein, “or” should be understood to have the same meaning as “and/or” as defined above. For example, when separating items in a list, “or” or “and/or” shall be interpreted as being inclusive, i.e., the inclusion of at least one, but also including more than one, of a number or list of elements, and, optionally, additional unlisted items. 
     The phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of “including,” “comprising,” “having,” “containing”, “involving”, and variations thereof, is meant to encompass the items listed thereafter and additional items. 
     Having described several embodiments of the invention in detail, various modifications, and improvements will readily occur to those skilled in the art. Such modifications and improvements are intended to be within the spirit and scope of the invention. Accordingly, the foregoing description is by way of example only, and is not intended as limiting.