Patent Publication Number: US-2019197064-A1

Title: Query Construction on Online Social Networks

Description:
PRIORITY 
     This application is a continuation under 35 U.S.C. § 120 of U.S. patent application Ser. No. 15/270,896, filed 20 Sep. 2016, which is a continuation under 35 U.S.C. § 120 of U.S. patent application Ser. No. 14/179,357, filed 12 Feb. 2014, issued as U.S. Pat. No. 9,477,760 on 25 Oct. 2016, each of which is incorporated herein by reference. 
    
    
     TECHNICAL FIELD 
     This disclosure generally relates to social graphs and performing searches for objects within a social-networking environment. 
     BACKGROUND 
     A social-networking system, which may include a social-networking website, may enable its users (such as persons or organizations) to interact with it and with each other through it. The social-networking system may, with input from a user, create and store in the social-networking system a user profile associated with the user. The user profile may include demographic information, communication-channel information, and information on personal interests of the user. The social-networking system may also, with input from a user, create and store a record of relationships of the user with other users of the social-networking system, as well as provide services (e.g. wall posts, photo-sharing, event organization, messaging, games, or advertisements) to facilitate social interaction between or among users. 
     The social-networking system may transmit over one or more networks content or messages related to its services to a mobile or other computing device of a user. A user may also install software applications on a mobile or other computing device of the user for accessing a user profile of the user and other data within the social-networking system. The social-networking system may generate a personalized set of content objects to display to a user, such as a newsfeed of aggregated stories of other users connected to the user. 
     Social-graph analysis views social relationships in terms of network theory consisting of nodes and edges. Nodes represent the individual actors within the networks, and edges represent the relationships between the actors. The resulting graph-based structures are often very complex. There can be many types of nodes and many types of edges for connecting nodes. In its simplest form, a social graph is a map of all of the relevant edges between all the nodes being studied. 
     SUMMARY OF PARTICULAR EMBODIMENTS 
     In particular embodiments, a system may generate a search query using a multi-step implementation and a graphical interface to a natural language search-query interface. A complete search query may be divided into different tokens, such as, for example, a grammar token and a completion token. The system may select a particular grammar token from a list of pre-determined grammar tokens. The pre-determined grammar tokens may correspond to nodes and edges of a social graph and the selection of the grammar token may lock-in the grammar token into the search query. The list of pre-determined grammar tokens may be based on text inputted into a query field by the user. For example, the user typing “ph” in a query field may be provided grammar tokens “Photos of,” “Photos by,” or “Photos from.” In response to the user selecting a particular grammar token, the system may display one or more completion tokens. The completion tokens may correspond to a social-graph object associated with the querying user, such as for example, photos or profile pages of “friends” of the user. The list of completion tokens presented to the user may be based on the selected grammar token and possibly based on one or more additional factors, such as, for example the affinity of the social-graph objects associated with the grammar token. In addition, completion tokens with low relevance to the selected grammar token may be filtered out. The user may select a particular completion token to complete the search query and initiate the search by the server. Additional grammar tokens or completion tokens may be appended to the search query, for example, by selecting the query field. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  illustrates an example network environment associated with a social-networking system. 
         FIG. 2  illustrates an example social graph. 
         FIG. 3  illustrates an example webpage of an online social network. 
         FIG. 4 . illustrates an example mobile client system. 
         FIGS. 5-6  illustrate an example user interface (UI) on a mobile client system. 
         FIGS. 7-8  illustrate an example completion-token page on a mobile client system. 
         FIG. 9  illustrates an example search-results page on a mobile client system. 
         FIG. 10  illustrates an example categories page on a mobile client system. 
         FIG. 11  illustrates an example modifying completion-tokens page on a mobile client system. 
         FIG. 12  illustrates an example search-results page on a mobile client system. 
         FIG. 13  illustrates an example method for generating structured search queries. 
         FIG. 14  illustrates an example computer system. 
     
    
    
     DESCRIPTION OF EXAMPLE EMBODIMENTS 
       FIG. 1  illustrates an example network environment  100  associated with a social-networking system. Network environment  100  includes a client system  130 , a social-networking system  160 , and a third-party system  170  connected to each other by a network  110 . Although  FIG. 1  illustrates a particular arrangement of client system  130 , social-networking system  160 , third-party system  170 , and network  110 , this disclosure contemplates any suitable arrangement of client system  130 , social-networking system  160 , third-party system  170 , and network  110 . As an example and not by way of limitation, two or more of client system  130 , social-networking system  160 , and third-party system  170  may be connected to each other directly, bypassing network  110 . As another example, two or more of client system  130 , social-networking system  160 , and third-party system  170  may be physically or logically co-located with each other in whole or in part. Moreover, although  FIG. 1  illustrates a particular number of client systems  130 , social-networking systems  160 , third-party systems  170 , and networks  110 , this disclosure contemplates any suitable number of client systems  130 , social-networking systems  160 , third-party systems  170 , and networks  110 . As an example and not by way of limitation, network environment  100  may include multiple client system  130 , social-networking systems  160 , third-party systems  170 , and networks  110 . 
     This disclosure contemplates any suitable network  110 . As an example and not by way of limitation, one or more portions of network  110  may include an ad hoc network, an intranet, an extranet, a virtual private network (VPN), a local area network (LAN), a wireless LAN (WLAN), a wide area network (WAN), a wireless WAN (WWAN), a metropolitan area network (MAN), a portion of the Internet, a portion of the Public Switched Telephone Network (PSTN), a cellular telephone network, or a combination of two or more of these. Network  110  may include one or more networks  110 . 
     Links  150  may connect client system  130 , social-networking system  160 , and third-party system  170  to communication network  110  or to each other. This disclosure contemplates any suitable links  150 . In particular embodiments, one or more links  150  include one or more wireline (such as for example Digital Subscriber Line (DSL) or Data Over Cable Service Interface Specification (DOCSIS)), wireless (such as for example Wi-Fi or Worldwide Interoperability for Microwave Access (WiMAX)), or optical (such as for example Synchronous Optical Network (SONET) or Synchronous Digital Hierarchy (SDH)) links. In particular embodiments, one or more links  150  each include an ad hoc network, an intranet, an extranet, a VPN, a LAN, a WLAN, a WAN, a WWAN, a MAN, a portion of the Internet, a portion of the PSTN, a cellular technology-based network, a satellite communications technology-based network, another link  150 , or a combination of two or more such links  150 . Links  150  need not necessarily be the same throughout network environment  100 . One or more first links  150  may differ in one or more respects from one or more second links  150 . 
     In particular embodiments, client system  130  may be an electronic device including hardware, software, or embedded logic components or a combination of two or more such components and capable of carrying out the appropriate functionalities implemented or supported by client system  130 . As an example and not by way of limitation, a client system  130  may include a computer system such as a desktop computer, notebook or laptop computer, netbook, a tablet computer, e-book reader, GPS device, camera, personal digital assistant (PDA), handheld electronic device, cellular telephone, smartphone, other suitable electronic device, or any suitable combination thereof. This disclosure contemplates any suitable client systems  130 . A client system  130  may enable a network user at client system  130  to access network  110 . A client system  130  may enable its user to communicate with other users at other client systems  130 . 
     In particular embodiments, client system  130  may include a web browser  132 , such as MICROSOFT INTERNET EXPLORER, GOOGLE CHROME or MOZILLA FIREFOX, and may have one or more add-ons, plug-ins, or other extensions, such as TOOLBAR or YAHOO TOOLBAR. A user at client system  130  may enter a Uniform Resource Locator (URL) or other address directing the web browser  132  to a particular server (such as server  162 , or a server associated with a third-party system  170 ), and the web browser  132  may generate a Hyper Text Transfer Protocol (HTTP) request and communicate the HTTP request to server. The server may accept the HTTP request and communicate to client system  130  one or more Hyper Text Markup Language (HTML) files responsive to the HTTP request. Client system  130  may render a webpage based on the HTML files from the server for presentation to the user. This disclosure contemplates any suitable webpage files. As an example and not by way of limitation, webpages may render from HTML files, Extensible Hyper Text Markup Language (XHTML) files, or Extensible Markup Language (XML) files, according to particular needs. Such pages may also execute scripts such as, for example and without limitation, those written in JAVASCRIPT, JAVA, MICROSOFT SILVERLIGHT, combinations of markup language and scripts such as AJAX (Asynchronous JAVASCRIPT and XML), and the like. Herein, reference to a webpage encompasses one or more corresponding webpage files (which a browser may use to render the webpage) and vice versa, where appropriate. 
     In particular embodiments, social-networking system  160  may be a network-addressable computing system that can host an online social network. Social-networking system  160  may generate, store, receive, and transmit social-networking data, such as, for example, user-profile data, concept-profile data, social-graph information, or other suitable data related to the online social network. Social-networking system  160  may be accessed by the other components of network environment  100  either directly or via network  110 . In particular embodiments, social-networking system  160  may include one or more servers  162 . Each server  162  may be a unitary server or a distributed server spanning multiple computers or multiple datacenters. Servers  162  may be of various types, such as, for example and without limitation, web server, news server, mail server, message server, advertising server, file server, application server, exchange server, database server, proxy server, another server suitable for performing functions or processes described herein, or any combination thereof. In particular embodiments, each server  162  may include hardware, software, or embedded logic components or a combination of two or more such components for carrying out the appropriate functionalities implemented or supported by server  162 . In particular embodiments, social-networking system  164  may include one or more data stores  164 . Data stores  164  may be used to store various types of information. In particular embodiments, the information stored in data stores  164  may be organized according to specific data structures. In particular embodiments, each data store  164  may be a relational database. Particular embodiments may provide interfaces that enable a client system  130 , a social-networking system  160 , or a third-party system  170  to manage, retrieve, modify, add, or delete, the information stored in data store  164 . 
     In particular embodiments, social-networking system  160  may store one or more social graphs in one or more data stores  164 . In particular embodiments, a social graph may include multiple nodes—which may include multiple user nodes (each corresponding to a particular user) or multiple concept nodes (each corresponding to a particular concept)—and multiple edges connecting the nodes. Social-networking system  160  may provide users of the online social network the ability to communicate and interact with other users. In particular embodiments, users may join the online social network via social-networking system  160  and then add connections (i.e., relationships) to a number of other users of social-networking system  160  whom they want to be connected to. Herein, the term “friend” may refer to any other user of social-networking system  160  with whom a user has formed a connection, association, or relationship via social-networking system  160 . 
     In particular embodiments, social-networking system  160  may provide users with the ability to take actions on various types of items or objects, supported by social-networking system  160 . As an example and not by way of limitation, the items and objects may include groups or social networks to which users of social-networking system  160  may belong, events or calendar entries in which a user might be interested, computer-based applications that a user may use, transactions that allow users to buy or sell items via the service, interactions with advertisements that a user may perform, or other suitable items or objects. A user may interact with anything that is capable of being represented in social-networking system  160  or by an external system of third-party system  170 , which is separate from social-networking system  160  and coupled to social-networking system  160  via a network  110 . 
     In particular embodiments, social-networking system  160  may be capable of linking a variety of entities. As an example and not by way of limitation, social-networking system  160  may enable users to interact with each other as well as receive content from third-party systems  170  or other entities, or to allow users to interact with these entities through an application programming interfaces (API) or other communication channels. 
     In particular embodiments, a third-party system  170  may include one or more types of servers, one or more data stores, one or more interfaces, including but not limited to APIs, one or more web services, one or more content sources, one or more networks, or any other suitable components, e.g., that servers may communicate with. A third-party system  170  may be operated by a different entity from an entity operating social-networking system  160 . In particular embodiments, however, social-networking system  160  and third-party systems  170  may operate in conjunction with each other to provide social-networking services to users of social-networking system  160  or third-party systems  170 . In this sense, social-networking system  160  may provide a platform, or backbone, which other systems, such as third-party systems  170 , may use to provide social-networking services and functionality to users across the Internet. 
     In particular embodiments, a third-party system  170  may include a third-party content object provider. A third-party content object provider may include one or more sources of content objects, which may be communicated to a client system  130 . As an example and not by way of limitation, content objects may include information regarding things or activities of interest to the user, such as, for example, movie show times, movie reviews, restaurant reviews, restaurant menus, product information and reviews, or other suitable information. As another example and not by way of limitation, content objects may include incentive content objects, such as coupons, discount tickets, gift certificates, or other suitable incentive objects. 
     In particular embodiments, social-networking system  160  also includes user-generated content objects, which may enhance a user&#39;s interactions with social-networking system  160 . User-generated content may include anything a user can add, upload, send, or “post” to social-networking system  160 . As an example and not by way of limitation, a user communicates posts to social-networking system  160  from a client system  130 . Posts may include data such as status updates or other textual data, location information, photos, videos, links, music or other similar data or media. Content may also be added to social-networking system  160  by a third-party through a “communication channel,” such as a newsfeed or stream. 
     In particular embodiments, social-networking system  160  may include a variety of servers, sub-systems, programs, modules, logs, and data stores. In particular embodiments, social-networking system  160  may include one or more of the following: a web server, action logger, API-request server, relevance-and-ranking engine, content-object classifier, notification controller, action log, third-party-content-object-exposure log, inference module, authorization/privacy server, search module, ad-targeting module, user-interface module, user-profile store, connection store, third-party content store, or location store. Social-networking system  160  may also include suitable components such as network interfaces, security mechanisms, load balancers, failover servers, management-and-network-operations consoles, other suitable components, or any suitable combination thereof. In particular embodiments, social-networking system  160  may include one or more user-profile stores for storing user profiles. A user profile may include, for example, biographic information, demographic information, behavioral information, social information, or other types of descriptive information, such as work experience, educational history, hobbies or preferences, interests, affinities, or location. Interest information may include interests related to one or more categories. Categories may be general or specific. As an example and not by way of limitation, if a user “likes” an article about a brand of shoes the category may be the brand, or the general category of “shoes” or “clothing.” A connection store may be used for storing connection information about users. The connection information may indicate users who have similar or common work experience, group memberships, hobbies, educational history, or are in any way related or share common attributes. The connection information may also include user-defined connections between different users and content (both internal and external). A web server may be used for linking social-networking system  160  to one or more client systems  130  or one or more third-party system  170  via network  110 . The web server may include a mail server or other messaging functionality for receiving and routing messages between social-networking system  160  and one or more client systems  130 . An API-request server may allow a third-party system  170  to access information from social-networking system  160  by calling one or more APIs. An action logger may be used to receive communications from a web server about a user&#39;s actions on or off social-networking system  160 . In conjunction with the action log, a third-party-content-object log may be maintained of user exposures to third-party-content objects. A notification controller may provide information regarding content objects to a client system  130 . Information may be pushed to a client system  130  as notifications, or information may be pulled from client system  130  responsive to a request received from client system  130 . Authorization servers may be used to enforce one or more privacy settings of the users of social-networking system  160 . A privacy setting of a user determines how particular information associated with a user can be shared. The authorization server may allow users to opt in or opt out of having their actions logged by social-networking system  160  or shared with other systems (e.g., third-party system  170 ), such as, for example, by setting appropriate privacy settings. Third-party-content-object stores may be used to store content objects received from third parties, such as a third-party system  170 . Location stores may be used for storing location information received from client systems  130  associated with users. Ad-pricing modules may combine social information, the current time, location information, or other suitable information to provide relevant advertisements, in the form of notifications, to a user. 
     Social Graphs 
       FIG. 2  illustrates example social graph  200 . In particular embodiments, social-networking system  160  may store one or more social graphs  200  in one or more data stores. In particular embodiments, social graph  200  may include multiple nodes—which may include multiple user nodes  202  or multiple concept nodes  204 —and multiple edges  206  connecting the nodes. Example social graph  200  illustrated in  FIG. 2  is shown, for didactic purposes, in a two-dimensional visual map representation. In particular embodiments, a social-networking system  160 , client system  130 , or third-party system  170  may access social graph  200  and related social-graph information for suitable applications. The nodes and edges of social graph  200  may be stored as data objects, for example, in a data store (such as a social-graph database). Such a data store may include one or more searchable or queryable indexes of nodes or edges of social graph  200 . 
     In particular embodiments, a user node  202  may correspond to a first user of social-networking system  160 . As an example and not by way of limitation, a user may be an individual (human user), an entity (e.g., an enterprise, business, or third-party application), or a group (e.g., of individuals or entities) that interacts or communicates with or over social-networking system  160 . In particular embodiments, when a first user registers for an account with social-networking system  160 , social-networking system  160  may create a first user node  202  corresponding to the user, and store the user node  202  in one or more data stores. Users and user nodes  202  described herein may, where appropriate, refer to registered users and user nodes  202  associated with registered users. In addition or as an alternative, users and user nodes  202  described herein may, where appropriate, refer to users that have not registered with social-networking system  160 . In particular embodiments, a user node  202  may be associated with information provided by a user or information gathered by various systems, including social-networking system  160 . As an example and not by way of limitation, a user may provide his or her name, profile picture, contact information, birth date, sex, marital status, family status, employment, education background, preferences, interests, or other demographic information. In particular embodiments, a user node  202  may be associated with one or more data objects corresponding to information associated with a user. In particular embodiments, a user node  202  may correspond to one or more webpages. 
     In particular embodiments, a concept node  204  may correspond to a concept. As an example and not by way of limitation, a concept may correspond to a place (such as, for example, a movie theater, restaurant, landmark, or city); a website (such as, for example, a website associated with social-networking system  160  or a third-party website associated with a web-application server); an entity (such as, for example, a person, business, group, sports team, or celebrity); a resource (such as, for example, an audio file, video file, digital photo, text file, structured document, or application) which may be located within social-networking system  160  or on an external server, such as a web-application server; real or intellectual property (such as, for example, a sculpture, painting, movie, game, song, idea, photograph, or written work); a game; an activity; an idea or theory; another suitable concept; or two or more such concepts. A concept node  204  may be associated with information of a concept provided by a user or information gathered by various systems, including social-networking system  160 . As an example and not by way of limitation, information of a concept may include a name or a title; one or more images (e.g., an image of the cover page of a book); a location (e.g., an address or a geographical location); a website (which may be associated with a URL); contact information (e.g., a phone number or an email address); other suitable concept information; or any suitable combination of such information. In particular embodiments, a concept node  204  may be associated with one or more data objects corresponding to information associated with concept node  204 . In particular embodiments, a concept node  204  may correspond to one or more webpages. 
     In particular embodiments, a node in social graph  200  may represent or be represented by a webpage (which may be referred to as a “profile page”). Profile pages may be hosted by or accessible to social-networking system  160 . Profile pages may also be hosted on third-party websites associated with a third-party server  170 . As an example and not by way of limitation, a profile page corresponding to a particular external webpage may be the particular external webpage and the profile page may correspond to a particular concept node  204 . Profile pages may be viewable by all or a selected subset of other users. As an example and not by way of limitation, a user node  202  may have a corresponding user-profile page in which the corresponding user may add content, make declarations, or otherwise express himself or herself. As another example and not by way of limitation, a concept node  204  may have a corresponding concept-profile page in which one or more users may add content, make declarations, or express themselves, particularly in relation to the concept corresponding to concept node  204 . 
     In particular embodiments, a concept node  204  may represent a third-party webpage or resource hosted by a third-party system  170 . The third-party webpage or resource may include, among other elements, content, a selectable or other icon, or other inter-actable object (which may be implemented, for example, in JavaScript, AJAX, or PHP codes) representing an action or activity. As an example and not by way of limitation, a third-party webpage may include a selectable icon such as “like,” “check in,” “eat,” “recommend,” or another suitable action or activity. A user viewing the third-party webpage may perform an action by selecting one of the icons (e.g., “eat”), causing a client system  130  to transmit to social-networking system  160  a message indicating the user&#39;s action. In response to the message, social-networking system  160  may create an edge (e.g., an “eat” edge) between a user node  202  corresponding to the user and a concept node  204  corresponding to the third-party webpage or resource and store edge  206  in one or more data stores. 
     In particular embodiments, a pair of nodes in social graph  200  may be connected to each other by one or more edges  206 . An edge  206  connecting a pair of nodes may represent a relationship between the pair of nodes. In particular embodiments, an edge  206  may include or represent one or more data objects or attributes corresponding to the relationship between a pair of nodes. As an example and not by way of limitation, a first user may indicate that a second user is a “friend” of the first user. In response to this indication, social-networking system  160  may transmit a “friend request” to the second user. If the second user confirms the “friend request,” social-networking system  160  may create an edge  206  connecting the first user&#39;s user node  202  to the second user&#39;s user node  202  in social graph  200  and store edge  206  as social-graph information in one or more of data stores  24 . In the example of  FIG. 2 , social graph  200  includes an edge  206  indicating a friend relation between user nodes  202  of user “A” and user “B” and an edge indicating a friend relation between user nodes  202  of user “C” and user “B.” Although this disclosure describes or illustrates particular edges  206  with particular attributes connecting particular user nodes  202 , this disclosure contemplates any suitable edges  206  with any suitable attributes connecting user nodes  202 . As an example and not by way of limitation, an edge  206  may represent a friendship, family relationship, business or employment relationship, fan relationship, follower relationship, visitor relationship, subscriber relationship, superior/subordinate relationship, reciprocal relationship, non-reciprocal relationship, another suitable type of relationship, or two or more such relationships. Moreover, although this disclosure generally describes nodes as being connected, this disclosure also describes users or concepts as being connected. Herein, references to users or concepts being connected may, where appropriate, refer to the nodes corresponding to those users or concepts being connected in social graph  200  by one or more edges  206 . 
     In particular embodiments, an edge  206  between a user node  202  and a concept node  204  may represent a particular action or activity performed by a user associated with user node  202  toward a concept associated with a concept node  204 . As an example and not by way of limitation, as illustrated in  FIG. 2 , a user may “like,” “attended,” “played,” “listened,” “cooked,” “worked at,” or “watched” a concept, each of which may correspond to a edge type or subtype. A concept-profile page corresponding to a concept node  204  may include, for example, a selectable “check in” icon (such as, for example, a clickable “check in” icon) or a selectable “add to favorites” icon. Similarly, after a user clicks these icons, social-networking system  160  may create a “favorite” edge or a “check in” edge in response to a user&#39;s action corresponding to a respective action. As another example and not by way of limitation, a user (user “C”) may listen to a particular song (“Imagine”) using a particular application (SPOTIFY, which is an online music application). In this case, social-networking system  160  may create a “listened” edge  206  and a “used” edge (as illustrated in  FIG. 2 ) between user nodes  202  corresponding to the user and concept nodes  204  corresponding to the song and application to indicate that the user listened to the song and used the application. Moreover, social-networking system  160  may create a “played” edge  206  (as illustrated in  FIG. 2 ) between concept nodes  204  corresponding to the song and the application to indicate that the particular song was played by the particular application. In this case, “played” edge  206  corresponds to an action performed by an external application (SPOTIFY) on an external audio file (the song “Imagine”). Although this disclosure describes particular edges  206  with particular attributes connecting user nodes  202  and concept nodes  204 , this disclosure contemplates any suitable edges  206  with any suitable attributes connecting user nodes  202  and concept nodes  204 . Moreover, although this disclosure describes edges between a user node  202  and a concept node  204  representing a single relationship, this disclosure contemplates edges between a user node  202  and a concept node  204  representing one or more relationships. As an example and not by way of limitation, an edge  206  may represent both that a user likes and has used at a particular concept. Alternatively, another edge  206  may represent each type of relationship (or multiples of a single relationship) between a user node  202  and a concept node  204  (as illustrated in  FIG. 2  between user node  202  for user “E” and concept node  204  for “SPOTIFY”). 
     In particular embodiments, social-networking system  160  may create an edge  206  between a user node  202  and a concept node  204  in social graph  200 . As an example and not by way of limitation, a user viewing a concept-profile page (such as, for example, by using a web browser or a special-purpose application hosted by the user&#39;s client system  130 ) may indicate that he or she likes the concept represented by the concept node  204  by clicking or selecting a “Like” icon, which may cause the user&#39;s client system  130  to transmit to social-networking system  160  a message indicating the user&#39;s liking of the concept associated with the concept-profile page. In response to the message, social-networking system  160  may create an edge  206  between user node  202  associated with the user and concept node  204 , as illustrated by “like” edge  206  between the user and concept node  204 . In particular embodiments, social-networking system  160  may store an edge  206  in one or more data stores. In particular embodiments, an edge  206  may be automatically formed by social-networking system  160  in response to a particular user action. As an example and not by way of limitation, if a first user uploads a picture, watches a movie, or listens to a song, an edge  206  may be formed between user node  202  corresponding to the first user and concept nodes  204  corresponding to those concepts. Although this disclosure describes forming particular edges  206  in particular manners, this disclosure contemplates forming any suitable edges  206  in any suitable manner. 
     Typeahead Processes 
     In particular embodiments, one or more client-side and/or backend (server-side) processes may implement and utilize a “typeahead” feature that may automatically attempt to match social-graph elements (e.g., user nodes  202 , concept nodes  204 , or edges  206 ) to information currently being entered by a user in an input form rendered in conjunction with a requested webpage (such as, for example, a user-profile page, a concept-profile page, a search-results webpage, or another suitable page of the online social network), which may be hosted by or accessible in the social-networking system  160 . In particular embodiments, as a user is entering text to make a declaration, the typeahead feature may attempt to match the string of textual characters being entered in the declaration to strings of characters (e.g., names, descriptions) corresponding to user, concepts, or edges and their corresponding elements in the social graph  200 . In particular embodiments, when a match is found, the typeahead feature may automatically populate the form with a reference to the social-graph element (such as, for example, the node name/type, node ID, edge name/type, edge ID, or another suitable reference or identifier) of the existing social-graph element. The typeahead functionality described herein can also be used to match inputs to social-graph elements when generating grammar tokens and/or completion tokens, as described below. 
     In particular embodiments, as a user types or otherwise enters text into a form used to add content or make declarations in various sections of the user&#39;s profile page, home page, or other page, the typeahead process may work in conjunction with one or more frontend (client-side) and/or backend (server-side) typeahead processes (hereinafter referred to simply as “typeahead process”) executing at (or within) the social-networking system  160  (e.g., within servers  162 ), to interactively and virtually instantaneously (as appearing to the user) attempt to auto-populate the form with a term or terms corresponding to names of existing social-graph elements, or terms associated with existing social-graph elements, determined to be the most relevant or best match to the characters of text entered by the user as the user enters the characters of text. Utilizing the social-graph information in a social-graph database or information extracted and indexed from the social-graph database, including information associated with nodes and edges, the typeahead processes, in conjunction with the information from the social-graph database, as well as potentially in conjunction with various others processes, applications, or databases located within or executing within social-networking system  160 , may be able to predict a user&#39;s intended declaration with a high degree of precision. However, the social-networking system  160  can also provide users with the freedom to enter essentially any declaration they wish, enabling users to express themselves freely. 
     In particular embodiments, as a user enters text characters into a form box or other field, the typeahead processes may attempt to identify existing social-graph elements (e.g., user nodes  202 , concept nodes  204 , or edges  206 ) that match the string of characters entered in the user&#39;s declaration as the user is entering the characters. In particular embodiments, as the user enters characters into a form box, the typeahead process may read the string of entered textual characters. As each keystroke is made, the frontend-typeahead process may transmit the entered character string as a request (or call) to the backend-typeahead process executing within social-networking system  160 . In particular embodiments, the typeahead processes may communicate via AJAX (Asynchronous JavaScript and XML) or other suitable techniques, and particularly, asynchronous techniques. In particular embodiments, the request may be, or comprise, an XMLHTTPRequest (XHR) enabling quick and dynamic sending and fetching of results. In particular embodiments, the typeahead process may also transmit before, after, or with the request a section identifier (section ID) that identifies the particular section of the particular page in which the user is making the declaration. In particular embodiments, a user ID parameter may also be sent, but this may be unnecessary in some embodiments, as the user may already be “known” based on the user having logged into (or otherwise been authenticated by) the social-networking system  160 . 
     In particular embodiments, the typeahead process may use one or more matching algorithms to attempt to identify matching social-graph elements. In particular embodiments, when a match or matches are found, the typeahead process may transmit a response (which may utilize AJAX or other suitable techniques) to the user&#39;s client system  130  that may include, for example, the names (name strings) or descriptions of the matching social-graph elements as well as, potentially, other metadata associated with the matching social-graph elements. As an example and not by way of limitation, if a user entering the characters “pok” into a query field, the typeahead process may display a drop-down menu that displays names of matching existing profile pages and respective user nodes  202  or concept nodes  204 , such as a profile page named or devoted to “poker” or “pokemon”, which the user can then click on or otherwise select thereby confirming the desire to declare the matched user or concept name corresponding to the selected node. As another example and not by way of limitation, upon clicking “poker,” the typeahead process may auto-populate, or causes the web browser  132  to auto-populate, the query field with the declaration “poker”. In particular embodiments, the typeahead process may simply auto-populate the field with the name or other identifier of the top-ranked match rather than display a drop-down menu. The user may then confirm the auto-populated declaration simply by keying “enter” on his or her keyboard or by clicking on the auto-populated declaration. 
     More information on typeahead processes may be found in U.S. patent application Ser. No. 12/763,162, filed 19 Apr. 2010, and U.S. patent application Ser. No. 13/556,072, filed 23 Jul. 2012, which are incorporated by reference. 
     Structured Search Queries 
       FIG. 3  illustrates an example webpage of an online social network. In particular embodiments, a user may submit a query to the social-networking system  160  by inputting text into query field  350 . A user of an online social network may search for information relating to a specific subject matter (e.g., users, concepts, external content or resource) by providing a short phrase describing the subject matter, often referred to as a “search query,” to a search engine. The query may be an unstructured text query and may comprise one or more text strings (which may include one or more n-grams). In general, a user may input any character string into query field  350  to search for content on the social-networking system  160  that matches the text query. The social-networking system  160  may then search a data store  164  (or, in particular, a social-graph database) to identify content matching the query. The search engine may conduct a search based on the query phrase using various search algorithms and generate search results that identify resources or content (e.g., user-profile pages, content-profile pages, or external resources) that are most likely to be related to the search query. To conduct a search, a user may input or transmit a search query to the search engine. In response, the search engine may identify one or more resources that are likely to be related to the search query, each of which may individually be referred to as a “search result,” or collectively be referred to as the “search results” corresponding to the search query. The identified content may include, for example, social-graph elements (i.e., user nodes  202 , concept nodes  204 , edges  206 ), profile pages, external webpages, or any combination thereof. The social-networking system  160  may then generate a search-results webpage with search results corresponding to the identified content and transmit the search-results webpage to the user. The search results may be presented to the user, often in the form of a list of links on the search-results webpage, each link being associated with a different webpage that contains some of the identified resources or content. In particular embodiments, each link in the search results may be in the form of a Uniform Resource Locator (URL) that specifies where the corresponding webpage is located and the mechanism for retrieving it. The social-networking system  160  may then transmit the search-results webpage to the web browser  132  on the user&#39;s client system  130 . The user may then click on the URL links or otherwise select the content from the search-results webpage to access the content from the social-networking system  160  or from an external system (such as, for example, a third-party system  170 ), as appropriate. The resources may be ranked and presented to the user according to their relative degrees of relevance to the search query. The search results may also be ranked and presented to the user according to their relative degree of relevance to the user. In other words, the search results may be personalized for the querying user based on, for example, social-graph information, user information, search or browsing history of the user, or other suitable information related to the user. In particular embodiments, ranking of the resources may be determined by a ranking algorithm implemented by the search engine. As an example and not by way of limitation, resources that are more relevant to the search query or to the user may be ranked higher than the resources that are less relevant to the search query or the user. In particular embodiments, the search engine may limit its search to resources and content on the online social network. However, in particular embodiments, the search engine may also search for resources or contents on other sources, such as a third-party system  170 , the internet or World Wide Web, or other suitable sources. Although this disclosure describes querying the social-networking system  160  in a particular manner, this disclosure contemplates querying the social-networking system  160  in any suitable manner. 
     In particular embodiments, the typeahead processes described herein may be applied to search queries entered by a user. As an example and not by way of limitation, as a user enters text characters into a search field, a typeahead process may attempt to identify one or more user nodes  202 , concept nodes  204 , or edges  206  that match the string of characters entered search field as the user is entering the characters. As the typeahead process receives requests or calls including a string or n-gram from the text query, the typeahead process may perform or causes to be performed a search to identify existing social-graph elements (i.e., user nodes  202 , concept nodes  204 , edges  206 ) having respective names, types, categories, or other identifiers matching the entered text. The typeahead process may use one or more matching algorithms to attempt to identify matching nodes or edges. When a match or matches are found, the typeahead process may transmit a response to the user&#39;s client system  130  that may include, for example, the names (name strings) of the matching nodes as well as, potentially, other metadata associated with the matching nodes. The typeahead process may then display a drop-down menu  300  that displays names of matching existing profile pages and respective user nodes  202  or concept nodes  204 , and displays names of matching edges  206  that may connect to the matching user nodes  202  or concept nodes  204 , which the user can then click on or otherwise select thereby confirming the desire to search for the matched user or concept name corresponding to the selected node, or to search for users or concepts connected to the matched users or concepts by the matching edges. Alternatively, the typeahead process may simply auto-populate the form with the name or other identifier of the top-ranked match rather than display a drop-down menu  300 . The user may then confirm the auto-populated declaration simply by keying “enter” on a keyboard or by clicking on the auto-populated declaration. Upon user confirmation of the matching nodes and edges, the typeahead process may transmit a request that informs the social-networking system  160  of the user&#39;s confirmation of a query containing the matching social-graph elements. In response to the request transmitted, the social-networking system  160  may automatically (or alternately based on an instruction in the request) call or otherwise search a social-graph database for the matching social-graph elements, or for social-graph elements connected to the matching social-graph elements as appropriate. Although this disclosure describes applying the typeahead processes to search queries in a particular manner, this disclosure contemplates applying the typeahead processes to search queries in any suitable manner. 
     In connection with search queries and search results, particular embodiments may utilize one or more systems, components, elements, functions, methods, operations, or steps disclosed in U.S. patent application Ser. No. 11/503,093, filed 11 Aug. 2006, U.S. patent application Ser. No. 12/977,027, filed 22 Dec. 2010, and U.S. patent application Ser. No. 12/978,265, filed 23 Dec. 2010, which are incorporated by reference. 
     In particular embodiments, in response to a text query received from a first user (i.e., the querying user), the social-networking system  160  may generate one or more structured queries rendered in a natural-language syntax, where each structured query includes query tokens that correspond to one or more identified social-graph elements. By providing suggested structured queries in response to a user&#39;s text query, the social-networking system  160  may provide a powerful way for users of the online social network to search for elements represented in the social graph  200  based on their social-graph attributes and their relation to various social-graph elements. Structured queries may allow a querying user to search for content that is connected to particular users or concepts in the social graph  200  by particular edge types. As an example and not by way of limitation, the social-networking system  160  may receive an unstructured text query from a first user. In response, the social-networking system  160  (via, for example, a server-side element detection process) may access the social graph  200  and then parse the text query to identify social-graph elements that corresponded to n-grams from the text query. The social-networking system  160  may then access a grammar model, such as a context-free grammar model, which includes a plurality of grammars. These grammars may be visualized as a grammar forest that is organized as an ordered tree with a plurality of non-terminal and terminal tokens. The identified social-graph elements may be used as terminal tokens (“query tokens”) in the grammars. Once these terminal tokens have been identified (for example, by using a semantic tree that corresponds to the text query from the user), the social-networking system  160  may traverse the grammar forest to identify intersecting non-terminal nodes. Each grammar represented by one of these intersecting non-terminal nodes may then be selected. The selected grammars may then be used to generate one or more structured queries that include the query tokens referencing the identified social-graph elements. These structured queries may be based on strings generated by the grammars, such that they are rendered with references to the appropriate social-graph elements using a natural-language syntax. The structured queries may be transmitted to the first user and displayed in a drop-down menu  300  (via, for example, a client-side typeahead process), where the first user can then select an appropriate query to search for the desired content. Some of the advantages of using the structured queries described herein include finding users of the online social network based upon limited information, bringing together virtual indexes of content from the online social network based on the relation of that content to various social-graph elements, or finding content related to you and/or your friends. By using this process, the output of the natural-language rendering process may be efficiently parsed, for example, to generate modified or alternative structured queries. Furthermore, since the rules used by this process are derived from the grammar model, any modification to the rules of the grammar model can be immediately reflected in the rendering process. Although this disclosure describes generating particular structured queries in a particular manner, this disclosure contemplates generating any suitable structured queries in any suitable manner. 
     In particular embodiments, the social-networking system  160  may receive from a querying/first user (corresponding to a first user node  202 ) an unstructured text query. As an example and not by way of limitation, a first user may want to search for other users who: (1) are first-degree friends of the first user; and (2) are associated with Stanford University (i.e., the user nodes  202  are connected by an edge  206  to the concept node  204  corresponding to the school “Stanford”). The first user may then enter a text query “friends stanford” into query field  350 . As the first user enters this text query into query field  350 , the social-networking system  160  may provide various suggested structured queries, as illustrated in drop-down menus  300 . As used herein, an unstructured text query refers to a simple text string inputted by a user. The text query may, of course, be structured with respect to standard language/grammar rules (e.g. English language grammar). However, the text query will ordinarily be unstructured with respect to social-graph elements. In other words, a simple text query will not ordinarily include embedded references to particular social-graph elements. Thus, as used herein, a structured query refers to a query that contains references to particular social-graph elements, allowing the search engine to search based on the identified elements. Furthermore, the text query may be unstructured with respect to formal query syntax. In other words, a simple text query will not necessarily be in the format of a query command that is directly executable by a search engine. Although this disclosure describes receiving particular queries in a particular manner, this disclosure contemplates receiving any suitable queries in any suitable manner. 
     In particular embodiments, social-networking system  160  may parse the unstructured text query (also simply referred to as a search query) received from the first user (i.e., the querying user) to identify one or more n-grams. In general, an n-gram is a contiguous sequence of n items from a given sequence of text or speech. The items may be characters, phonemes, syllables, letters, words, base pairs, prefixes, or other identifiable items from the sequence of text or speech. The n-gram may comprise one or more characters of text (letters, numbers, punctuation, etc.) entered by the querying user. An n-gram of size one can be referred to as a “unigram,” of size two can be referred to as a “bigram” or “digram,” of size three can be referred to as a “trigram,” and so on. Each n-gram may include one or more parts from the text query received from the querying user. In particular embodiments, each n-gram may comprise a character string (e.g., one or more characters of text) entered by the first user. As an example and not by way of limitation, the social-networking system  160  may parse the text query “friends stanford” to identify the following n-grams: friends; stanford; friends stanford. As another example and not by way of limitation, the social-networking system  160  may parse the text query “friends in palo alto” to identify the following n-grams: friends; in; palo; alto; friends in; in palo; palo alto; friend in palo; in palo alto; friends in palo alto. In particular embodiments, each n-gram may comprise a contiguous sequence of n items from the text query. Although this disclosure describes parsing particular queries in a particular manner, this disclosure contemplates parsing any suitable queries in any suitable manner. 
     In particular embodiments, social-networking system  160  may determine or calculate, for each n-gram identified in the text query, a score that the n-gram corresponds to a social-graph element. The score may be, for example, a confidence score, a probability, a quality, a ranking, another suitable type of score, or any combination thereof. As an example and not by way of limitation, the social-networking system  160  may determine a probability score (also referred to simply as a “probability”) that the n-gram corresponds to a social-graph element, such as a user node  202 , a concept node  204 , or an edge  206  of social graph  200 . The probability score may indicate the level of similarity or relevance between the n-gram and a particular social-graph element. There may be many different ways to calculate the probability. The present disclosure contemplates any suitable method to calculate a probability score for an n-gram identified in a search query. In particular embodiments, the social-networking system  160  may determine a probability, p, that an n-gram corresponds to a particular social-graph element. The probability, p, may be calculated as the probability of corresponding to a particular social-graph element, k, given a particular search query, X. In other words, the probability may be calculated as p=(k|X). As an example and not by way of limitation, a probability that an n-gram corresponds to a social-graph element may calculated as an probability score denoted as p i,j,k . The input may be a text query X=(x 1 , x 2 , . . . , x N ), and a set of classes. For each (i:j) and a class k, the social-networking system  160  may compute p i,j,k =p(class(x i:j )=k|X). As an example and not by way of limitation, the n-gram “stanford” could be scored with respect to the following social-graph elements as follows: school “Stanford University”=0.7; location “Stanford, Calif.”=0.2; user “Allen Stanford”=0.1. As another example and not by way of limitation, the n-gram “friends” could be scored with respect to the following social-graph elements as follows: user “friends”=0.9; television show “Friends”=0.1. In particular embodiments, the social-networking system  160  may user a forward-backward algorithm to determine the probability that a particular n-gram corresponds to a particular social-graph element. For a given n-gram within a text query, the social-networking system  160  may use both the preceding and succeeding n-grams to determine which particular social-graph elements correspond to the given n-gram. In particular embodiments, the identified social-graph elements may be used to generate a query command that is executable by a search engine. The query command may be a structured semantic query with defined functions that accept specific arguments. As an example and not by way of limitation, the text query “friend me mark” could be parsed to form the query command: intersect(friend(me), friend(Mark)). In other words, the query is looking for nodes in the social graph that intersect the querying user (“me”) and the user “Mark” (i.e., those user nodes  202  that are connected to both the user node  202  of the querying user by a friend-type edge  206  and the user node  202  for the user “Mark” by a friend-type edge  206 ). Although this disclosure describes determining whether n-grams correspond to social-graph elements in a particular manner, this disclosure contemplates determining whether n-grams correspond to social-graph elements in any suitable manner. Moreover, although this disclosure describes determining whether an n-gram corresponds to a social-graph element using a particular type of score, this disclosure contemplates determining whether an n-gram corresponds to a social-graph element using any suitable type of score. 
     In particular embodiments, social-networking system  160  may identify one or more edges  206  having a probability greater than an edge-threshold probability. Each of the identified edges  206  may correspond to at least one of the n-grams. As an example and not by way of limitation, the n-gram may only be identified as corresponding to an edge, k, if p i,j,k &gt;p edge-threshold . Furthermore, each of the identified edges  206  may be connected to at least one of the identified nodes. In other words, the social-networking system  160  may only identify edges  206  or edge-types that are connected to user nodes  202  or concept nodes  204  that have previously been identified as corresponding to a particular n-gram. Edges  206  or edge-types that are not connected to any previously identified node are typically unlikely to correspond to a particular n-gram in a search query. By filtering out or ignoring these edges  206  and edge-types, the social-networking system  160  may more efficiently search the social graph  200  for relevant social-graph elements. As an example and not by way of limitation, referencing  FIG. 2 , for a text query containing “went to Stanford,” where an identified concept node  204  is the school “Stanford,” the social-networking system  160  may identify the edges  206  corresponding to “worked at” and the edges  206  corresponding to “attended,” both of which are connected to the concept node  204  for “Stanford.” Thus, the n-gram “went to” may be identified as corresponding to these edges  206 . However, for the same text query, the social-networking system  160  may not identify the edges  206  corresponding to “like” or “fan” in the social graph  200  because the “Stanford” node does not have any such edges connected to it. Although this disclosure describes identifying edges  206  that correspond to n-grams in a particular manner, this disclosure contemplates identifying edges  206  that correspond to n-grams in any suitable manner. 
     In particular embodiments, social-networking system  160  may identify one or more user nodes  202  or concept nodes  204  having a probability greater than a node-threshold probability. Each of the identified nodes may correspond to at least one of the n-grams. As an example and not by way of limitation, the n-gram may only be identified as corresponding to a node, k, if p i,j,k &gt;p node-threshold . Furthermore, each of the identified user nodes  202  or concept nodes  204  may be connected to at least one of the identified edges  206 . In other words, the social-networking system  160  may only identify nodes or nodes-types that are connected to edges  206  that have previously been identified as corresponding to a particular n-gram. Nodes or node-types that are not connected to any previously identified edges  206  are typically unlikely to correspond to a particular n-gram in a search query. By filtering out or ignoring these nodes and node-types, the social-networking system  160  may more efficiently search the social graph  200  for relevant social-graph elements. As an example and not by way of limitation, for a text query containing “worked at Apple,” where an identified edge  206  is “worked at,” the social-networking system  160  may identify the concept node  204  corresponding to the company APPLE, INC., which may have multiple edges  206  of “worked at” connected to it. However, for the same text query, the social-networking system  160  may not identify the concept node  204  corresponding to the fruit-type “apple,” which may have multiple “like” or “fan” edges connected to it, but no “worked at” edge connections. In particular embodiments, the node-threshold probability may differ for user nodes  202  and concept nodes  204 , and may differ even among these nodes (e.g., some concept nodes  204  may have different node-threshold probabilities than other concept nodes  204 ). As an example and not by way of limitation, an n-gram may be identified as corresponding to a user node  302 , k user , if p i,j,k &gt;p user-node-threshold , while an n-gram may be identified as corresponding to a concept node  304 , k concept , if p i,j,k &gt;p concept-node-threshold . In particular embodiments, the social-networking system  160  may only identify nodes that are within a threshold degree of separation of the user node  202  corresponding to the first user (i.e., the querying user). The threshold degree of separation may be, for example, one, two, three, or all. Although this disclosure describes identifying nodes that correspond to n-grams in a particular manner, this disclosure contemplates identifying nodes that correspond to n-grams in any suitable manner. 
     In particular embodiments, the social-networking system  160  may access a context-free grammar model comprising a plurality of grammars. Each grammar of the grammar model may comprise one or more non-terminal tokens (or “non-terminal symbols”) and one or more terminal tokens (or “terminal symbols”/“query tokens”), where particular non-terminal tokens may be replaced by terminal tokens. A grammar model is a set of formation rules for strings in a formal language. Although this disclosure describes accessing particular grammars, this disclosure contemplates any suitable grammars. 
     In particular embodiments, the social-networking system  160  may generate one or more strings using one or more grammars. To generate a string in the language, one begins with a string consisting of only a single start symbol. The production rules are then applied in any order, until a string that contains neither the start symbol nor designated non-terminal symbols is produced. In a context-free grammar, the production of each non-terminal symbol of the grammar is independent of what is produced by other non-terminal symbols of the grammar. The non-terminal symbols may be replaced with terminal symbols (i.e., terminal tokens or query tokens). Some of the query tokens may correspond to identified nodes or identified edges, as described previously. A string generated by the grammar may then be used as the basis for a structured query containing references to the identified nodes or identified edges. The string generated by the grammar may be rendered in a natural-language syntax, such that a structured query based on the string is also rendered in natural language. A context-free grammar is a grammar in which the left-hand side of each production rule consists of only a single non-terminal symbol. A probabilistic context-free grammar is a tuple &lt;Σ, N, S, P&gt;, where the disjoint sets Σ and N specify the terminal and non-terminal symbols, respectively, with SϵN being the start symbol. P is the set of productions, which take the form E→ξ(p), with EϵN, ξϵ(Σ∩N) + , and p=Pr(E→ξ), the probability that E will be expanded into the string ξ. The sum of probabilities p over all expansions of a given non-terminal E must be one. Although this disclosure describes generating strings in a particular manner, this disclosure contemplates generating strings in any suitable manner. 
     In particular embodiments, the social-networking system  160  may identify one or more query tokens corresponding to the previously identified nodes and edges. In other words, if an identified node or identified edge may be used as a query token in a particular grammar, that query token may be identified by the social-networking system  160 . As an example and not by way of limitation, an example grammar may be: [user][user-filter][school]. The non-terminal symbols [user], [user-filter], and [school] could then be determined based n-grams in the received text query. For the text query “friends stanford”, this query could be parsed by using the grammar as, for example, “[friends][who go to][Stanford University]” or “[friends][who work at][Stanford University]”. As another example and not by way of limitation, an example grammar may be [user][user-filter][location]. For the text query “friends stanford”, this query could be parsed by using the grammar as, for example, “[friends][who live in][Stanford, Calif.]”. In both the example cases above, if the n-grams of the received text query could be used as query tokens, then these query tokens may be identified by the social-networking system  160 . Although this disclosure describes identifying particular query tokens in a particular manner, this disclosure contemplates identifying any suitable query tokens in any suitable manner. 
     In particular embodiments, the social-networking system  160  may select one or more grammars having at least one query token corresponding to each of the previously identified nodes and edges. Only particular grammars may be used depending on the n-grams identified in the text query. So the terminal tokens of all available grammars should be examined to find those that match the identified n-grams from the text query. In other words, if a particular grammar can use all of the identified nodes and edges as query tokens, that grammar may be selected by the social-networking system  160  as a possible grammar to use for generating a structured query. This is effectively a type of bottom-up parsing, where the possible query tokens are used to determine the applicable grammar to apply to the query. As an example and not by way of limitation, for the text query “friends stanford”, the social-networking system may identify the query tokens of [friends] and [Stanford University]. Terminal tokens of the grammars from the grammar model may be identified, as previously discussed. Any grammar that is able to use both the [friends] and the [Stanford University] tokens may then be selected. For example, the grammar [user][user-filter][school] may be selected because this grammar could use the [friends] and the [Stanford University] tokens as query tokens, such as by forming the strings “friends who go to Stanford University” or “friends who work at Stanford University”. Thus, if the n-grams of the received text query could be used as query tokens in the grammars, then these grammars may be selected by the social-networking system  160 . Similarly, if the received text query comprises n-grams that could not be used as query tokens in the grammar, that grammar may not be selected. Although this disclosure describes selecting particular grammars in a particular manner, this disclosure contemplates selecting any suitable grammars in any suitable manner. 
     In particular embodiments, the social-networking system  160  may select one or more grammars by analyzing a grammar forest formed by a plurality of grammars. The grammar forest may be organized as an ordered tree comprising a plurality of non-terminal tokens and a plurality of terminal tokens. Each grammar may be represented as a sub-tree within the grammar forest, and each sub-tree may adjoin other sub-trees via one or more additional non-terminal tokens. As an example and not by way of limitation, the social-networking system  160  may start by identifying all the terminal tokens (i.e., query tokens) in the grammar forest that correspond to identified nodes and edges corresponding to portions of a text query. Once these query tokens in the grammar forest have been identified, the social-networking system  160  may then traverse the grammar forest up from each of these query tokens to identify one or more intersecting non-terminal tokens. Once a non-terminal token has been identified where paths from all the query tokens intersect, that intersecting non-terminal token may be selected, and the one or more grammars adjoined to that intersecting non-terminal token in the grammar forest may then be selected. Although this disclosure describes selecting grammars in a particular manner, this disclosure contemplates selecting grammars in any suitable manner. 
     In particular embodiments, the social-networking system  160  may determine a score for each selected grammar. The score may be, for example, a confidence score, a probability, a quality, a ranking, another suitable type of score, or any combination thereof. The score may be based on the individual scores or probabilities associated with the query tokens used in the selected grammar. A grammar may have a higher relative score if it uses query tokens with relatively higher individual scores. As an example and not by way of limitation, continuing with the prior examples, the n-gram “stanford” could be scored with respect to the following social-graph elements as follows: school “Stanford University”=0.7; location “Stanford, Calif.”=0.2; user “Allen Stanford”=0.1. The n-gram “friends” could be scored with respect to the following social-graph elements as follows: user “friends”=0.9; television show “Friends”=0.1. Thus, the grammar [user] [user-filter] [school] may have a relatively high score if it uses the query tokens for the user “friends” and the school “Stanford University” (generating, for example, the string “friends who go to Stanford University”), both of which have relatively high individual scores. In contrast, the grammar [user] [user-filter] [user] may have relatively low score if it uses the query tokens for the user “friends” and the user “Allen Stanford” (generating, for example, the string “friends of Allen Stanford”), since the latter query token has a relatively low individual score. In particular embodiments, the social-networking system  160  may determine a score for a selected grammar based on the lengths of the paths traversed in order to identify the intersect token corresponding to the selected grammar. Grammars with lower-cost multi-paths (i.e., shorter paths) may be scored more highly than grammars with high-cost multi-paths (i.e., longer paths). In particular embodiments, the social-networking system  160  may determine a score for a selected grammar based on advertising sponsorship. An advertiser (such as, for example, the user or administrator of a particular profile page corresponding to a particular node) may sponsor a particular node such that a grammar that includes a query token referencing that sponsored node may be scored more highly. Although this disclosure describes determining particular scores for particular grammars in a particular manner, this disclosure contemplates determining any suitable scores for any suitable grammars in any suitable manner. 
     In particular embodiments, the social-networking system  160  may determine the score for a selected grammar based on the relevance of the social-graph elements corresponding to the query tokens of the grammar to the querying user (i.e., the first user, corresponding to a first user node  202 ). User nodes  202  and concept nodes  204  that are connected to the first user node  202  directly by an edge  206  may be considered relevant to the first user. Thus, grammars comprising query tokens corresponding to these relevant nodes and edges may be considered more relevant to the querying user. As an example and not by way of limitation, a concept node  204  connected by an edge  206  to a first user node  202  may be considered relevant to the first user node  202 . As used herein, when referencing a social graph  200  the term “connected” means a path exists within the social graph  200  between two nodes, wherein the path may comprise one or more edges  206  and zero or more intermediary nodes. In particular embodiments, nodes that are connected to the first user node  202  via one or more intervening nodes (and therefore two or more edges  206 ) may also be considered relevant to the first user. Furthermore, in particular embodiments, the closer the second node is to the first user node, the more relevant the second node may be considered to the first user node. That is, the fewer edges  206  separating the first user node  202  from a particular user node  202  or concept node  204  (i.e., the fewer degrees of separation), the more relevant that user node  202  or concept node  204  may be considered to the first user. As an example and not by way of limitation, as illustrated in  FIG. 2 , the concept node  204  corresponding to the school “Stanford” is connected to the user node  202  corresponding to User “C,” and thus the concept “Stanford” may be considered relevant to User “C.” As another example and not by way of limitation, the user node  202  corresponding to User “A” is connected to the user node  202  corresponding to User “C” via one intermediate node and two edges  206  (i.e., the intermediated user node  202  corresponding to User “B”), and thus User “A” may be considered relevant to User “C,” but because the user node  202  for User “A” is a second-degree connection with respect to User “C,” that particular concept node  204  may be considered less relevant than a user node  202  that is connected to the user node for User “C” by a single edge  206 , such as, for example, the user node  202  corresponding to User “B.” As yet another example and not by way of limitation, the concept node for “Online Poker” (which may correspond to an online multiplayer game) is not connected to the user node for User “C” by any pathway in social graph  200 , and thus the concept “Online Poker” may not be considered relevant to User “C.” In particular embodiments, a second node may only be considered relevant to the first user if the second node is within a threshold degree of separation of the first user node  202 . As an example and not by way of limitation, if the threshold degree of separation is three, then the user node  202  corresponding to User “D” may be considered relevant to the concept node  204  corresponding to the recipe “Chicken Parmesan,” which are within three degrees of each other on social graph  200  illustrated in  FIG. 2 . However, continuing with this example, the concept node  204  corresponding to the application “All About Recipes” would not be considered relevant to the user node  202  corresponding to User “D” because these nodes are four degrees apart in the social graph  200 . Although this disclosure describes determining whether particular social-graph elements (and thus their corresponding query tokens) are relevant to each other in a particular manner, this disclosure contemplates determining whether any suitable social-graph elements are relevant to each other in any suitable manner. Moreover, although this disclosure describes determining whether particular query tokens corresponding to user nodes  202  and concept nodes  204  are relevant to a querying user, this disclosure contemplates similarly determining whether any suitable query token (and thus any suitable node) is relevant to any other suitable user. 
     In particular embodiments, the social-networking system  160  may determine the score for a selected grammar based social-graph information corresponding to the query tokens of the grammar. As an example and not by way of limitation, when determining a probability, p, that an n-gram corresponds to a particular social-graph element, the calculation of the probability may also factor in social-graph information. Thus, the probability of corresponding to a particular social-graph element, k, given a particular search query, X, and social-graph information, G, may be calculated as p=(k|X, G). The individual probabilities for the identified nodes and edges may then be used to determine the score for a grammar using those social-graph elements as query tokens. In particular embodiments, the score for a selected grammar may be based on the degree of separation between the first user node  202  and the particular social-graph element used as a query token in the grammar. Grammars with query tokens corresponding to social-graph elements that are closer in the social graph  200  to the querying user (i.e., fewer degrees of separation between the element and the first user node  202 ) may be scored more highly than grammars using query tokens corresponding to social-graph elements that are further from the user (i.e., more degrees of separation). As an example and not by way of limitation, referencing  FIG. 2 , if user “B” inputs a text query of “chicken,” a grammar with a query token corresponding to the concept node  204  for the recipe “Chicken Parmesan,” which is connected to user “B” by an edge  206 , may have a relatively higher score than a grammar with a query token corresponding to other nodes associated with the n-gram chicken (e.g., concept nodes  204  corresponding to “chicken nuggets,” or “funky chicken dance”) that are not connected to user “B” in the social graph  200 . In particular embodiments, the score for a selected grammar may be based on the identified edges  206  corresponding to the query tokens of the grammar. If the social-networking system  160  has already identified one or more edges that correspond to n-grams in a received text query, those identified edges may then be considered when determining the score for a particular parsing of the text query by the grammar. If a particular grammar comprises query tokens that correspond to both identified nodes and identified edges, if the identified nodes are not actually connected to any of the identified edges, that particular grammar may be assigned a zero or null score. In particular embodiments, the score for a selected grammar may be based on the number of edges  206  connected to the nodes corresponding to query tokens of the grammar. Grammars comprising query tokens that corresponding to nodes with more connecting edges  206  may be more popular and more likely to be a target of a search query. As an example and not by way of limitation, if the concept node  204  for “Stanford, Calif.” is only connected by five edges while the concept node  204  for “Stanford University” is connected by five-thousand edges, when determining the score for grammars containing query tokens corresponding to either of these nodes, the social-networking system  160  may determine that the grammar with a query token corresponding to the concept node  204  for “Stanford University” has a relatively higher score than a grammar referencing the concept node  204  for “Stanford, Calif.” because of the greater number of edges connected to the former concept node  204 . In particular embodiments, the score for a selected grammar may be based on the search history associate with the first user (i.e., the querying user). Grammars with query tokens corresponding to nodes that the first user has previously accessed, or are relevant to the nodes the first user has previously accessed, may be more likely to be the target of the first user&#39;s search query. Thus, these grammars may be given a higher score. As an example and not by way of limitation, if first user has previously visited the “Stanford University” profile page but has never visited the “Stanford, Calif.” profile page, when determining the score for grammars with query tokens corresponding to these concepts, the social-networking system  160  may determine that the concept node  204  for “Stanford University” has a relatively high score, and thus the grammar using the corresponding query token, because the querying user has previously accessed the concept node  204  for the school. As another example and not by way of limitation, if the first user has previously visited the concept-profile page for the television show “Friends,” when determining the score for the grammar with the query token corresponding to that concept, the social-networking system  160  may determine that the concept node  204  corresponding to the television show “Friends” has a relatively high score, and thus the grammar using the corresponding query token, because the querying user has previously accessed the concept node  204  for that television show. Although this disclosure describes determining scores for particular grammars based on particular social-graph information in a particular manner, this disclosure contemplates determining scores for any suitable grammars based on any suitable social-graph information in any suitable manner. 
     In particular embodiments, social-networking system  160  may select one or more grammars having a score greater than a grammar-threshold score. Each of the selected grammars may contain query tokens that correspond to each of the identified nodes or identified edges (which correspond to n-grams of the received text query). In particular embodiments, the grammars may be ranked based on their determined scores, and only grammars within a threshold rank may be selected (e.g., top seven). Although this disclosure describes selecting grammars in a particular manner, this disclosure contemplates selecting grammars in any suitable manner. 
     In particular embodiments, social-networking system  160  may generate one or more structured queries corresponding to the selected grammars (e.g., those grammars having a score greater than a grammar-threshold score). Each structured query may be based on a string generated by the corresponding selected grammar. As an example and not by way of limitation, in response to the text query “friends stanford”, the grammar [user][user-filter] [school] may generate a string “friends who go to Stanford University”, where the non-terminal tokens [user], [user-filter], [school] of the grammar have been replaced by the terminal tokens [friends], [who go to], and [Stanford University], respectively, to generate the string. In particular embodiments, a string that is generated by grammar using a natural-language syntax may be rendered as a structured query in natural language. As an example and not by way of limitation, the structured query from the previous example uses the terminal token [who go to], which uses a natural-language syntax so that the string rendered by grammar is in natural language. The natural-language string generated by a grammar may then be rendered to form a structured query by modifying the query tokens corresponding to social-graph element to include references to those social-graph elements. As an example and not by way of limitation, the string “friends who go to Stanford University” may be rendered so that the query token for “Stanford University” appears in the structured query as a reference to the concept node  204  corresponding to the school “Stanford University”, where the reference may be include highlighting, an inline link, a snippet, another suitable reference, or any combination thereof. Each structured query may comprise query tokens corresponding to the corresponding selected grammar, where these query tokens correspond to one or more of the identified edges  206  and one or more of the identified nodes. Generating structured queries is described more below. 
     In particular embodiments, in response to a text query received from a first user (i.e., the querying user), social-networking system  160  may generate one or more structured queries rendered in a natural-language syntax, where each structured query includes query tokens that correspond to one or more identified social-graph elements. Structured queries may allow a querying user to search for content that is connected to particular users or concepts in the social graph  200  by particular edge types. As an example and not by way of limitation, social-networking system  160  may receive an unstructured text query from a first user. In response, social-networking system  160  (via, for example, a server-side element detection process) may access the social graph  200  and then parse the text query to identify social-graph elements that corresponded to n-grams from the text query. Social-networking system  160  may then access a grammar model, such as a context-free grammar model, which includes a plurality of grammars, described below. The identified social-graph elements may be used as terminal tokens (“query tokens”) in the grammar. The selected grammars may then be used to generate one or more structured queries that include the query tokens referencing the identified social-graph elements. These structured queries may be based on strings generated by the grammars, such that they are rendered with references to the appropriate social-graph elements using a natural-language syntax. The structured queries may be displayed in a drop-down menu  300  (via, for example, a client-side typeahead process), where the first user can then select an appropriate query to search for the desired content. Some of the advantages of using the structured queries described herein include finding users of the online social network based upon limited information, bringing together virtual indexes of content from the online social network based on the relation of that content to various social-graph elements, or finding content related to you and/or your friends. By using this process, the output of the natural-language rendering process may be efficiently parsed, for example, to generate modified or alternative structured queries. Furthermore, since the rules used by this process are derived from the grammar model, any modification to the rules of the grammar model can be immediately reflected in the rendering process. Although this disclosure describes and illustrates generating particular structured queries in a particular manner, this disclosure contemplates generating any suitable structured queries in any suitable manner. 
     In particular embodiments, social-networking system  160  may receive from a querying/first user (corresponding to a first user node  202 ) an unstructured text query. As an example and not by way of limitation, a first user may want to search for other users who: (1) are first-degree friends of the first user; and (2) are associated with Stanford University (i.e., the user nodes  202  are connected by an edge  206  to the concept node  204  corresponding to the school “Stanford”). The first user may then enter a text query “friends stanford” into search-query field  350 . As used herein, reference to an unstructured text query may refer to a simple text string inputted by a user. The text query may, of course, be structured with respect to standard language/grammar rules (e.g. English language grammar). However, the text query will ordinarily be unstructured with respect to social-graph elements. In other words, a simple text query will not ordinarily include embedded references to particular social-graph elements. Thus, as used herein, a structured query refers to a query that contains references to particular social-graph elements, allowing the search engine to search based on the identified elements. Furthermore, the text query may be unstructured with respect to formal query syntax. In other words, a simple text query will not necessarily be in the format of a query command that is directly executable by a search engine. Although this disclosure describes receiving particular queries in a particular manner, this disclosure contemplates receiving any suitable queries in any suitable manner. 
     In particular embodiments, in response to a structured query received from a querying user, the social-networking system  160  may generate one or more search results, where each search result matches (or substantially matches) the terms of the structured query. The social-networking system  160  may receive a structured query from a querying user. In response to the structured query, the social-networking system  160  may generate one or more search results corresponding to the structured query. Each search result may include link to a profile page and a description or summary of the profile page (or the node corresponding to that page). The search results may be presented and transmitted to the querying user as a search-results page. The structured query used to generate a particular search-results page is shown in query field  350 , and the various search results generated in response to the structured query are illustrated in a field for presented search results. In particular embodiments, the query field  350  may also serve as the title bar for the page. In other words, the title bar and query field  350  may effectively be a unified field on the search-results page. The search-results page may also include a field for modifying search results and a field for providing suggested searches. When generating the search results, the social-networking system  160  may generate one or more snippets for each search result, where the snippets are contextual information about the target of the search result (i.e., contextual information about the social-graph entity, profile page, or other content corresponding to the particular search result). Although this disclosure describes and illustrates particular search-results pages, this disclosure contemplates any suitable search-results pages. 
     More information on generating search results may be found in U.S. patent application Ser. No. 13/731,939, filed 31 Dec. 2012, which is incorporated by reference. 
     Query Construction 
       FIG. 4  illustrates an example mobile client system  130 . This disclosure contemplates mobile client system  130  taking any suitable physical form. In particular embodiments, mobile client system  130  may be a computing system as described below. As example and not by way of limitation, mobile client system  130  may be a single-board computer system (SBC) (such as, for example, a computer-on-module (COM) or system-on-module (SOM)), a laptop or notebook computer system, a mobile telephone, a smartphone, a personal digital assistant (PDA), a tablet computer system, or a combination of two or more of these. In particular embodiments, mobile client system  130  may have a touch sensor  132  as an input component. In the example of  FIG. 4 , touch sensor  132  is incorporated on a front surface of mobile client system  130 . In the case of capacitive touch sensors, there may be two types of electrodes: transmitting and receiving. These electrodes may be connected to a controller designed to drive the transmitting electrodes with electrical pulses and measure the changes in capacitance from the receiving electrodes caused by a touch or proximity input. In the example of  FIG. 4 , one or more antennae  134 A-B may be incorporated into one or more sides of mobile client system  130 . Antennae  134 A-B are components that convert electric current into radio waves, and vice versa. During transmission of signals, a transmitter applies an oscillating radio frequency (RF) electric current to terminals of antenna  134 A-B, and antenna  134 A-B radiates the energy of the applied the current as electromagnetic (EM) waves. During reception of signals, antennae  134 A-B convert the power of an incoming EM wave into a voltage at the terminals of antennae  134 A-B. The voltage may be transmitted to a receiver for amplification. 
     In particular embodiments, mobile client system  130  many include a communication component coupled to antennae  134 A-B for communicating with an Ethernet or other wire-based network or a wireless NIC (WNIC), wireless adapter for communicating with a wireless network, such as for example a WI-FI network or modem for communicating with a cellular network, such third generation mobile telecommunications (3G), or Long Term Evolution (LTE) network. This disclosure contemplates any suitable network and any suitable communication component  20  for it. As an example and not by way of limitation, mobile client system  130  may communicate with an ad hoc network, a personal area network (PAN), a local area network (LAN), a wide area network (WAN), a metropolitan area network (MAN), or one or more portions of the Internet or a combination of two or more of these. One or more portions of one or more of these networks may be wired or wireless. As another example, mobile client system  130  may communicate with a wireless PAN (WPAN) (such as, for example, a BLUETOOTH WPAN), a WI-FI network, a WI-MAX network, a cellular telephone network (such as, for example, a Global System for Mobile Communications (GSM), 3G, or LTE network), or other suitable wireless network or a combination of two or more of these. Mobile client system  130  may include any suitable communication component for any of these networks, where appropriate. 
       FIGS. 5-12  illustrate an example user interface (UI) of a mobile client system. In particular embodiments, a user may submit a query to the social-networking system  160  by inputting text into a search-query field  350  of the user interface of mobile client system  130 . As described above, a user of an online social network may search for information by providing a short phrase describing the subject matter, often referred to as a “search query,” to a search engine. Furthermore, a user may input any character string into search-query field  350  to search for social-graph entities on the social-networking system  160  that matches the text query. The typeahead functionality described previously can also be used to match inputs to social-graph elements when generating grammar tokens and/or completion tokens, as further described below. As described below, social-networking system  160  may generate one or more structured queries based on the text input into search-query field  350  by the user. 
     In particular embodiments, mobile client system  130  may generate one or more structured queries based query tokens, which may be divided into grammar tokens and completion tokens that may be selected by a querying user. As an example and not by way of limitation, structured queries may be generated by selecting one or more grammar tokens  510  and subsequently one or more completion tokens  710 . Herein, reference to a grammar token may refer to one or more social-graph elements of a partial structured query. As an example and not by way of limitation, grammar tokens of a structured query may correspond to partial structured queries such as [Photos of . . . ], [Friends of . . . ], or [Pages liked by . . . ], and which contain references to particular social-graph elements, as described below. Herein, reference to a completion token may refer to a one or more social-graph elements that completes a structured query that includes a grammar token. As an example and not by way of limitation, completion tokens of a structured query may correspond to partial structured queries such as [ . . . my friends], [ . . . current location], or [ . . . New York], and which contain references to particular social-graph elements, as described below. In particular embodiments, grammar tokens  510  or completion tokens  710  may be based on a natural-language string. A type associated with the social-graph elements referenced by the grammar token may be used to determine one or more completion tokens subsequently displayed to the querying user. In particular embodiments, a grammar-tokens page may be auto-populated in the null state with one or more grammar tokens. Selection of a particular grammar token  510 A may act to “lock-in” the nodes or edges referenced by grammar token  510 A into the search query. In particular embodiments, a completion token  710  displayed in completion-token page  730  may be used to add one or more terms and complete structured query  720 A. As an example and not by way of limitation, completion tokens  710  displayed in completion-token page  730  may correspond to particular types of matching social-graph elements of the selected grammar token  510 A. In particular embodiments, the querying user may want to modify completed structured query  720 A to further refine search results  910  through use of modifying completion tokens  1110 . As an example and not by way of limitation, a modified structured query  720 B may be generated that incorporates the additional node and additional edge referenced in the selected modifying completion token  1110 A. Although this disclosure describes generating structured queries in a particular manner on a particular type of client system, this disclosure contemplates generating structured queries in any suitable manner on any suitable type of client system. 
     As described above, one or more structured queries may include one or more grammar tokens  510  and one or more completion tokens  710 . In particular embodiments, mobile client system  130  may access one or more grammar tokens  510  in response to accessing search-query field  350 . Grammar tokens  510  may correspond to a particular grammar used by grammar models described above. In particular embodiments, grammar tokens  510  may include references to one or more nodes or one or more edges from the social graph  200 . The querying user may select a grammar token  510  that references particular nodes/edges of social-graph  200 . As an example and not by way of limitation,  FIGS. 5-6  illustrates an example grammar-tokens page  520  generated in response to detecting an input corresponding to initiating a search, such as for example a touch input in search-query field  350 . As illustrated in the example of  FIG. 5 , grammar-tokens page  520  may be auto-populated in the null state with grammar tokens  510 . In particular embodiments, grammar tokens  510  displayed in the null state may be derived based at least in part on popular search queries, preferences of the querying user, business intelligence, or any combination thereof. In particular embodiments, mobile client system  130  may parse an unstructured text query (also simply referred to as a search query) received from the querying user to identify one or more n-grams. As an example and not by way of limitation, grammar tokens  510  displayed in grammar-token page  530  may be ranked or modified in response to text provided in search-query field  350 , and which may also work in conjunction with the typeahead functionality described previously. For example, the querying user typing “ph” in search-query field  350  may be provided grammar tokens  510  [Photos of . . . ], [Photos by . . . ], or [Photos from . . . ]. As another example, mobile client system  130  may filter out grammar tokens  510  that do not match the provided text or identified n-grams, such as for example [Pages liked by . . . ]. 
     In particular embodiments, the displayed grammar tokens  510  may include a graphical element that may provide an indication of a type of social-graph elements that are referenced by the search results of the structured query corresponding to each grammar token  510 . As an example and not by way of limitation, grammar token [Photos of . . . ]  510  may have a graphical element  530 A indicating the search results associated with this grammar token  510  may include references to images. As another example, grammar token [Friends of . . . ]  510  may have a graphical element  530 B indicating the search results associated with this grammar token  510  may include references to profile pages of second users. Grammar tokens  510  displayed in grammar-tokens page  520  may include references to particular nodes and edges used in structured queries corresponding to each grammar token  510 . The querying user may then select one or more of these grammar tokens  510  to generate a partial structured query. As illustrated by the example of  FIG. 6 , the querying user may select grammar token  510 A [Friends of . . . ] through a touch input  610  detected by a touch sensor  132  of mobile client system  130 . As an example and not by way of limitation, grammar token  510 A [Friends of . . . ] may reference user nodes  202  connected to the querying user by a friend-type edge  206 . 
     In particular embodiments, selection of a particular grammar token  510 A may act to “lock-in” the nodes or edges referenced by grammar token  510 A into the search query. As illustrated by the example of  FIG. 7 , search-query field  350  may be auto-populated with a partial structured query  720  corresponding to the selected grammar token  510 A. In particular embodiments, mobile client system  130  may access one or more completion tokens  710  in response to selection of a particular grammar token  510 . An example completion-tokens page  730  may display completion tokens  710  in response to subsequently receiving an input corresponding to selection of a grammar token  510 A. For example, completion tokens  710  may correspond to a social-graph element associated with the querying user, such as for example, photos or profile of users connected to the querying user through a friend-type edge  206 . In particular embodiments, completion-token page  730  may display a pre-determined list of completion tokens  710 . As an example and not by way of limitation, one or more completion tokens  710  displayed in completion-token page  730  may correspond to particular types of matching social-graph elements of the selected grammar token  510 A. For example, in the case of grammar token  510  [Pages liked by . . . ], corresponding completion tokens  710  may include users connected to the querying user through a friend-type edge  206 . In particular embodiments, each completion token  710  may be based on a natural-language string that corresponds to a natural-language string of selected grammar token  510 A. 
     Completion tokens  710  displayed in completion-token page  730  may be used to complete structured query  720 A. As an example and not by way of limitation, selection of one of completion tokens  710  may add one or more terms to complete structured query  720 A. By providing these suggested completion tokens  710  to the querying user, the social-networking system  160  may provide a way for users to search for exactly what they are looking for. As described above, completion tokens  710  may include references to one or more nodes or one or more edges of the social graph  200 . In particular embodiments, one or more completion tokens  710  may be used to add a reference to one or more nodes or edges to complete structured query  720 A. The querying user may then select one or more of these completion tokens  710  to add the nodes/edges to complete partial structured query  720 . Example completion-tokens page  730 , illustrated in the example of  FIG. 7 , may be generated in response to selection of grammar token  510 A [Friends of . . . ]. As an example and not by way of limitation, the querying user may want to complete structured query  720 A by specifying a particular user corresponding to user nodes  202  connected to the querying user by a friend-type edge  206 . In this case, completion-tokens page  730  illustrated in the examples of  FIGS. 7-8  may display completion tokens  710  that correspond to particular users, such as for example, “Ryan L.”, “Russ Maschmeyer”, and “Mark Z.”, among others. As another example and not by way of limitation, completion tokens  710  may be identified as part of a typeahead process and displayed in response to subsequent text input. Continuing with the example illustrated in  FIG. 7 , if the user inputs the character “r”, the list of completion tokens may be refined to show “Ryan L.”, “Russ Maschmeyer”, and other users having names beginning with “r” while removing “Mark Z.” and other user from the list of possible completion tokens. In particular embodiments, the displayed completion tokens  710  may be derived from the top ranked results of a search index of users (or user “vertical”) stored on social-networking system  160 . As another example, completion tokens  710  displayed in completion-tokens page  730  may be ranked based at least in part on the selected grammar token  530 A and the affinity of the social-graph elements associated with selected grammar token  530 A. For example, in a case where the querying user selects a particular grammar token  510  (e.g. [Photos of . . . ]), a completion token  510  corresponding to “user A” may be ranked higher than completion token  510  corresponding to “user B.” In contrast, in the case where the querying user selects different, but similar, grammar token  510  (e.g. [Photos by . . . ]), completion token  510  corresponding to “user B” may be ranked higher than completion token  510  corresponding to “user A.” In other words, when grammar token  510  [Photos of . . . ] is selected, photos of user A may be ranked higher than photos of user B. In contrast, when grammar token  510  [Photos by . . . ] is selected, photos taken by user B may be ranked higher than photos taken by user A. 
     The querying user may then select one or more of these completion tokens  710  to add the referenced nodes or edges to complete partial structured query  720 , thereby filtering the search results by particular social-graph elements. As illustrated in the example of  FIG. 8 , the selection may be performed through a input  610  by the querying user, such as for example, a touch input on the display of mobile client  130 . As an example and not by way of limitation, the querying user may select completion token  710 A [ . . . my friends] that corresponds to user nodes  202  with a higher degree of separation from user node  202  of the querying user. In response to the selection from the querying user, mobile client system  130  may complete structured query  720 A to include a reference to the added social-graph elements. As illustrated in the example of  FIG. 8 , once completion token  710 A is selected, e.g. through an input  610 , by the querying user, completed structured query  720 A may be generated using an appropriate grammar, such that the completed structured query  720 A is rendered using a natural-language syntax. Although this disclosure describes generating structured queries in a particular manner, this disclosure contemplates generating structured queries in any suitable manner. In particular embodiments, completed structured query  720 A may be sent to social-networking system  160  in response to selection of one or more completion tokens  710 A. In particular embodiments, completed structured query  720 A may be sent to social-networking system  160  in response to an input provided by the querying user, such as for example, clicking a graphical element of completion-tokens page  730 . 
     As illustrated in the example of  FIG. 9 , an example search-results page  920  of mobile client system  130  may display search results  910  returned by social-networking system  160  in response to receiving completed structured query  720 A. In particular embodiments, search results  910  may correspond to the type of social-graph elements indicated by the graphical element  530 A-B associated with selected grammar token  510 A, as described above. As an example and not by way of limitation, search-results page  920 , illustrated in the example of  FIG. 9 , may display search results  910  that includes one or more profile pages that match a type of social-graph elements indicated by graphical element  530 B associated with selected grammar token  510 A or that correspond to particular types of matching social-graph elements of the selected grammar token  510 A. 
     The querying user may want to modify completed structured query  720 A to refine search results  910 . In particular embodiments, search results  910  may be refined through use of modifying completion tokens  1110 . Furthermore, modifying completion tokens  1110  may be clustered into particular categories  1010 . As an example and not by way of limitation, categories  1010  may correspond to modifying completion tokens  1120  associated with “Employer”, “School”, “Current City”, “Hometown”, “Relationship Status”, “Interested in”, “Friendship”, “Gender”, “Name”, “Likes”, or any combination thereof. As illustrated in the example of  FIG. 10 , an example category page  1020  may display one or more categories  1010  of modifying completion tokens  1120  in response to receiving an input corresponding to an indication the querying user may want to modify completed structured query  720 A. As an example and not by way of limitation, may access category page  1020 , for example, by clicking or otherwise selecting a particular graphic element (e.g. a button) or by accessing search-query field  350 . In particular embodiments, the querying user may select one or more modifying completion tokens  1110  associated with particular categories  1010 . As illustrated in the example of  FIG. 10 , the querying user may modify completed structured query  720 A by providing an input  610  selecting category  1010 A [Current City]. 
     As illustrated in the example of  FIG. 11 , example modification page  1120  may display modifying completion tokens  1110  corresponding to the selected category  1010 A. In particular embodiments, modifying completion tokens  1110  may include references to one or more modifying nodes or one or more modifying edges of social graph  200 . As described above, modifying completion tokens  1110  may be ranked and displayed on example modification page  1120 . In particular embodiments, mobile client system  130  may generate a modified structured query  720 B in response to a selection of one or more of the modifying completion tokens  1110 . In particular embodiments, mobile client system  130  may generate a modified structured query  720 B comprising references to the selected nodes and the selected edges from the completed structured query  720 A, and each modifying node or modifying edge referenced in the selected modifying completion token  1110 A. As an example and not by way of limitation, for the completed structured query  720 A “Friends of my friends” and selected category  1010 A [Current City], mobile client system  130  may generate modifying completion token  1110 A [New York, New York] (which may reference connections to the concept node  204  for “New York” by a live-in-type edge  206 ). Mobile client system  130  may then generate modified structured query  720 B “Friends of my friends who live in New York”, which incorporates the additional node and additional edge referenced in the selected modifying completion token  1110 A. 
     In particular embodiments, the querying user may modify completed structured query  720 A to further refine search results  910  by selecting modifying completion tokens  1110  through completion-tokens page  730 , illustrated in the example of  FIG. 7 . As an example and not by way of limitation, completion-tokens page  730  may be displayed in response to the querying user providing an input indicating the querying user may want to modify completed structured query  720 A, such as for example, accessing search-query field  350 . As another example, modifying completion tokens  1110  may be identified as part of a typeahead process and displayed in response to subsequent text input. In particular embodiments, one or more modifying completion tokens  1110  displayed in completion-token page  730  may correspond to particular types of matching social-graph elements of the completed structured query  720 A. In particular embodiments, each modifying completion token  1110  may be based on a natural-language string that corresponds to a natural-language string of the selected grammar token  510 A and completion token  710 A. As described below, modified completion tokens  1110  may be ranked based at least in part on the selected grammar token  530 A and the affinity of the social-graph elements associated with selected grammar token  530 A. Although this disclosure describes generating particular modified structured queries in a particular manner, this disclosure contemplates generating any suitable modified structured queries in any suitable manner. 
     In particular embodiments, the social-networking system  160  may score one or more completion tokens  710  to complete a structured query  720 . In particular embodiments, when generating a set of completion tokens  710  to display to a querying user, only those completion tokens  710  having a score greater than a threshold score may be included in the set of query modifications that are actually transmitted. The threshold score may include, for example, a confidence score, a probability, a quality, a ranking, another suitable type of score, or any combination thereof. As an example and not by way of limitation, the social-networking system  160  may determine a ranking for each completion token  710 , where only the top six ranked completion tokens  710  are displayed to the querying user. In particular embodiments, the social-networking system  160  may determine a score for a completion token  710  based on the social relevance of completion token  710  to partial structured query  720 . Completion tokens  710  that reference social-graph elements that are more closely connected or otherwise relevant to the querying user may be scored more highly than completion tokens  710  that reference social-graph elements that are not as closely connected or are otherwise less relevant to the querying user. 
     In particular embodiments, modifying completion tokens  1110  may be scored similarly. In particular embodiments, the social-networking system  160  may determine a score for modifying completion tokens  1110  based on a search history associated with the querying user. Modifying completion tokens  1110  referencing social-graph elements that the querying user has previously accessed, or are relevant to nodes/profile pages the querying user has previously accessed, may be more likely to be relevant to the user&#39;s modified structured query  720 B. Thus, these modifying completion tokens  1110  may be given a higher relative score. As an example and not by way of limitation, if the querying user has previously search for “My friends at Stanford University”, then the social-networking system  160  may determine that the querying user is interested in user nodes  202  connected to the concept node  204  for “Stanford University.” Thus, in response to subsequent queries, the social-networking system  160  may rank modifying completion tokens  1110  referencing “Stanford University” more highly than other modifying completion tokens  1110  because of the querying user&#39;s history of interest in that type of contextual information. Although this disclosure describes scoring completion or modifying completion tokens in a particular manner, this disclosure contemplates scoring completion or modifying completion tokens in any suitable manner. 
     As illustrated in the example of  FIG. 12 , an example search-results page  920  of mobile client system  130  may display search results  910  returned by social-networking system  160  in response to receiving modified structured query  720 B. In particular embodiments, search-results page  920  illustrated in the example of  FIG. 12 , may display search results  910  that correspond to particular types of matching social-graph elements of selected modifying completion token  1110 A as well as completed structured query  720 A. 
       FIG. 13  illustrates an example method for generating structured search queries. The method may begin at step  1310 , where a client system may access a set of nodes of a social graph of an online social network. In particular embodiments, the social graph includes a number of nodes and a number of edges connecting the nodes. Furthermore, each of the edges between two of the nodes may represent a single degree of separation between them. In particular embodiments, the nodes may include first nodes that each correspond to a concept or a second user associated with the online social network and a second node corresponding to the first user. At step  1320 , the client system may access one or more grammar tokens. In particular embodiments, each grammar token may include references to zero or more second nodes and one or more edges. Furthermore, each grammar token may correspond to a particular type of completion token and each grammar token may be based on a natural-language string. As described above, example grammar tokens may include, for example, [Photos of . . . ], [Friends of . . . ], or [Pages liked by . . . ]. At step  1330 , the client system may receive from the first user a selection of one of the grammar tokens. At step  1340 , the client system may access one or more completion tokens. In particular embodiments, each completion token may include references to one or more second nodes and zero or more edges. Each completion token may be of the particular type corresponding to the selected grammar token. In particular embodiments, each completion token is based on a natural-language string corresponding to the natural-language string of the selected grammar token. As described above, example completion tokens may include, for example, [ . . . my friends], [ . . . current location], or [ . . . New York]. At step  1350 , the client system may receive from the first user a selection of one of the completion tokens. At step  1360 , the client system may generate one or more structured queries corresponding to the selected grammar token and the selected completion token. In particular embodiments, each structured query may include references to the zero or more of the second nodes and the one or more edges referenced in the selected grammar token and references to the one or more of the second nodes and the zero or more of the edges of the selected completion token. Particular embodiments may repeat one or more steps of the method of  FIG. 13 , where appropriate. Although this disclosure describes and illustrates particular steps of the method of  FIG. 13  as occurring in a particular order, this disclosure contemplates any suitable steps of the method of  FIG. 13  occurring in any suitable order. Moreover, although this disclosure describes and illustrates particular components, devices, or systems carrying out particular steps of the method of  FIG. 13 , this disclosure contemplates any suitable combination of any suitable components, devices, or systems carrying out any suitable steps of the method of  FIG. 13 . 
     Social Graph Affinity and Coefficient 
     In particular embodiments, social-networking system  160  may determine the social-graph affinity (which may be referred to herein as “affinity”) of various social-graph entities for each other. Affinity may represent the strength of a relationship or level of interest between particular objects associated with the online social network, such as users, concepts, content, actions, advertisements, other objects associated with the online social network, or any suitable combination thereof. Affinity may also be determined with respect to objects associated with third-party systems  170  or other suitable systems. An overall affinity for a social-graph entity for each user, subject matter, or type of content may be established. The overall affinity may change based on continued monitoring of the actions or relationships associated with the social-graph entity. Although this disclosure describes determining particular affinities in a particular manner, this disclosure contemplates determining any suitable affinities in any suitable manner. 
     In particular embodiments, social-networking system  160  may measure or quantify social-graph affinity using an affinity coefficient (which may be referred to herein as “coefficient”). The coefficient may represent or quantify the strength of a relationship between particular objects associated with the online social network. The coefficient may also represent a probability or function that measures a predicted probability that a user will perform a particular action based on the user&#39;s interest in the action. In this way, a user&#39;s future actions may be predicted based on the user&#39;s prior actions, where the coefficient may be calculated at least in part on a history of the user&#39;s actions. Coefficients may be used to predict any number of actions, which may be within or outside of the online social network. As an example and not by way of limitation, these actions may include various types of communications, such as sending messages, posting content, or commenting on content; various types of an observation actions, such as accessing or viewing profile pages, media, or other suitable content; various types of coincidence information about two or more social-graph entities, such as being in the same group, tagged in the same photograph, checked-in at the same location, or attending the same event; or other suitable actions. Although this disclosure describes measuring affinity in a particular manner, this disclosure contemplates measuring affinity in any suitable manner. 
     In particular embodiments, social-networking system  160  may use a variety of factors to calculate a coefficient. These factors may include, for example, user actions, types of relationships between objects, location information, other suitable factors, or any combination thereof. In particular embodiments, different factors may be weighted differently when calculating the coefficient. The weights for each factor may be static or the weights may change according to, for example, the user, the type of relationship, the type of action, the user&#39;s location, and so forth. Ratings for the factors may be combined according to their weights to determine an overall coefficient for the user. As an example and not by way of limitation, particular user actions may be assigned both a rating and a weight while a relationship associated with the particular user action is assigned a rating and a correlating weight (e.g., so the weights total 100%). To calculate the coefficient of a user towards a particular object, the rating assigned to the user&#39;s actions may comprise, for example, 60% of the overall coefficient, while the relationship between the user and the object may comprise 40% of the overall coefficient. In particular embodiments, the social-networking system  160  may consider a variety of variables when determining weights for various factors used to calculate a coefficient, such as, for example, the time since information was accessed, decay factors, frequency of access, relationship to information or relationship to the object about which information was accessed, relationship to social-graph entities connected to the object, short- or long-term averages of user actions, user feedback, other suitable variables, or any combination thereof. As an example and not by way of limitation, a coefficient may include a decay factor that causes the strength of the signal provided by particular actions to decay with time, such that more recent actions are more relevant when calculating the coefficient. The ratings and weights may be continuously updated based on continued tracking of the actions upon which the coefficient is based. Any type of process or algorithm may be employed for assigning, combining, averaging, and so forth the ratings for each factor and the weights assigned to the factors. In particular embodiments, social-networking system  160  may determine coefficients using machine-learning algorithms trained on historical actions and past user responses, or data farmed from users by exposing them to various options and measuring responses. Although this disclosure describes calculating coefficients in a particular manner, this disclosure contemplates calculating coefficients in any suitable manner. 
     In particular embodiments, social-networking system  160  may calculate a coefficient based on a user&#39;s actions. Social-networking system  160  may monitor such actions on the online social network, on a third-party system  170 , on other suitable systems, or any combination thereof. Any suitable type of user actions may be tracked or monitored. Typical user actions include viewing profile pages, creating or posting content, interacting with content, tagging or being tagged in images, joining groups, listing and confirming attendance at events, checking-in at locations, liking particular pages, creating pages, and performing other tasks that facilitate social action. In particular embodiments, social-networking system  160  may calculate a coefficient based on the user&#39;s actions with particular types of content. The content may be associated with the online social network, a third-party system  170 , or another suitable system. The content may include users, profile pages, posts, news stories, headlines, instant messages, chat room conversations, emails, advertisements, pictures, video, music, other suitable objects, or any combination thereof. Social-networking system  160  may analyze a user&#39;s actions to determine whether one or more of the actions indicate an affinity for subject matter, content, other users, and so forth. As an example and not by way of limitation, if a user may make frequently posts content related to “coffee” or variants thereof, social-networking system  160  may determine the user has a high coefficient with respect to the concept “coffee”. Particular actions or types of actions may be assigned a higher weight and/or rating than other actions, which may affect the overall calculated coefficient. As an example and not by way of limitation, if a first user emails a second user, the weight or the rating for the action may be higher than if the first user simply views the user-profile page for the second user. 
     In particular embodiments, social-networking system  160  may calculate a coefficient based on the type of relationship between particular objects. Referencing the social graph  200 , social-networking system  160  may analyze the number and/or type of edges  206  connecting particular user nodes  202  and concept nodes  204  when calculating a coefficient. As an example and not by way of limitation, user nodes  202  that are connected by a spouse-type edge (representing that the two users are married) may be assigned a higher coefficient than a user nodes  202  that are connected by a friend-type edge. In other words, depending upon the weights assigned to the actions and relationships for the particular user, the overall affinity may be determined to be higher for content about the user&#39;s spouse than for content about the user&#39;s friend. In particular embodiments, the relationships a user has with another object may affect the weights and/or the ratings of the user&#39;s actions with respect to calculating the coefficient for that object. As an example and not by way of limitation, if a user is tagged in first photo, but merely likes a second photo, social-networking system  160  may determine that the user has a higher coefficient with respect to the first photo than the second photo because having a tagged-in-type relationship with content may be assigned a higher weight and/or rating than having a like-type relationship with content. In particular embodiments, social-networking system  160  may calculate a coefficient for a first user based on the relationship one or more second users have with a particular object. In other words, the connections and coefficients other users have with an object may affect the first user&#39;s coefficient for the object. As an example and not by way of limitation, if a first user is connected to or has a high coefficient for one or more second users, and those second users are connected to or have a high coefficient for a particular object, social-networking system  160  may determine that the first user should also have a relatively high coefficient for the particular object. In particular embodiments, the coefficient may be based on the degree of separation between particular objects. The lower coefficient may represent the decreasing likelihood that the first user will share an interest in content objects of the user that is indirectly connected to the first user in the social graph  200 . As an example and not by way of limitation, social-graph entities that are closer in the social graph  200  (i.e., fewer degrees of separation) may have a higher coefficient than entities that are further apart in the social graph  200 . 
     In particular embodiments, social-networking system  160  may calculate a coefficient based on location information. Objects that are geographically closer to each other may be considered to be more related or of more interest to each other than more distant objects. In particular embodiments, the coefficient of a user towards a particular object may be based on the proximity of the object&#39;s location to a current location associated with the user (or the location of a client system  130  of the user). A first user may be more interested in other users or concepts that are closer to the first user. As an example and not by way of limitation, if a user is one mile from an airport and two miles from a gas station, social-networking system  160  may determine that the user has a higher coefficient for the airport than the gas station based on the proximity of the airport to the user. 
     In particular embodiments, social-networking system  160  may perform particular actions with respect to a user based on coefficient information. Coefficients may be used to predict whether a user will perform a particular action based on the user&#39;s interest in the action. A coefficient may be used when generating or presenting any type of objects to a user, such as advertisements, search results, news stories, media, messages, notifications, or other suitable objects. The coefficient may also be utilized to rank and order such objects, as appropriate. In this way, social-networking system  160  may provide information that is relevant to user&#39;s interests and current circumstances, increasing the likelihood that they will find such information of interest. In particular embodiments, social-networking system  160  may generate content based on coefficient information. Content objects may be provided or selected based on coefficients specific to a user. As an example and not by way of limitation, the coefficient may be used to generate media for the user, where the user may be presented with media for which the user has a high overall coefficient with respect to the media object. As another example and not by way of limitation, the coefficient may be used to generate advertisements for the user, where the user may be presented with advertisements for which the user has a high overall coefficient with respect to the advertised object. In particular embodiments, social-networking system  160  may generate search results based on coefficient information. Search results for a particular user may be scored or ranked based on the coefficient associated with the search results with respect to the querying user. As an example and not by way of limitation, search results corresponding to objects with higher coefficients may be ranked higher on a search-results page than results corresponding to objects having lower coefficients. 
     In particular embodiments, social-networking system  160  may calculate a coefficient in response to a request for a coefficient from a particular system or process. To predict the likely actions a user may take (or may be the subject of) in a given situation, any process may request a calculated coefficient for a user. The request may also include a set of weights to use for various factors used to calculate the coefficient. This request may come from a process running on the online social network, from a third-party system  170  (e.g., via an API or other communication channel), or from another suitable system. In response to the request, social-networking system  160  may calculate the coefficient (or access the coefficient information if it has previously been calculated and stored). In particular embodiments, social-networking system  160  may measure an affinity with respect to a particular process. Different processes (both internal and external to the online social network) may request a coefficient for a particular object or set of objects. Social-networking system  160  may provide a measure of affinity that is relevant to the particular process that requested the measure of affinity. In this way, each process receives a measure of affinity that is tailored for the different context in which the process will use the measure of affinity. 
     In connection with social-graph affinity and affinity coefficients, particular embodiments may utilize one or more systems, components, elements, functions, methods, operations, or steps disclosed in U.S. patent application Ser. No. 11/503,093, filed 11 Aug. 2006, U.S. patent application Ser. No. 12/977,027, filed 22 Dec. 2010, U.S. patent application Ser. No. 12/978,265, filed 23 Dec. 2010, and U.S. patent application Ser. No. 13/632,869, field 1 Oct. 2012, each of which is incorporated by reference. 
     Systems and Methods 
       FIG. 14  illustrates an example computer system  1400 . In particular embodiments, one or more computer systems  1400  perform one or more steps of one or more methods described or illustrated herein. In particular embodiments, one or more computer systems  1400  provide functionality described or illustrated herein. In particular embodiments, software running on one or more computer systems  1400  performs one or more steps of one or more methods described or illustrated herein or provides functionality described or illustrated herein. Particular embodiments include one or more portions of one or more computer systems  1400 . Herein, reference to a computer system may encompass a computing device, and vice versa, where appropriate. Moreover, reference to a computer system may encompass one or more computer systems, where appropriate. 
     This disclosure contemplates any suitable number of computer systems  1400 . This disclosure contemplates computer system  1400  taking any suitable physical form. As example and not by way of limitation, computer system  1400  may be an embedded computer system, a system-on-chip (SOC), a single-board computer system (SBC) (such as, for example, a computer-on-module (COM) or system-on-module (SOM)), a desktop computer system, a laptop or notebook computer system, an interactive kiosk, a mainframe, a mesh of computer systems, a mobile telephone, a personal digital assistant (PDA), a server, a tablet computer system, or a combination of two or more of these. Where appropriate, computer system  1400  may include one or more computer systems  1400 ; be unitary or distributed; span multiple locations; span multiple machines; span multiple data centers; or reside in a cloud, which may include one or more cloud components in one or more networks. Where appropriate, one or more computer systems  1400  may perform without substantial spatial or temporal limitation one or more steps of one or more methods described or illustrated herein. As an example and not by way of limitation, one or more computer systems  1400  may perform in real time or in batch mode one or more steps of one or more methods described or illustrated herein. One or more computer systems  1400  may perform at different times or at different locations one or more steps of one or more methods described or illustrated herein, where appropriate. 
     In particular embodiments, computer system  1400  includes a processor  1402 , memory  1404 , storage  1406 , an input/output (I/O) interface  1408 , a communication interface  1410 , and a bus  1412 . Although this disclosure describes and illustrates a particular computer system having a particular number of particular components in a particular arrangement, this disclosure contemplates any suitable computer system having any suitable number of any suitable components in any suitable arrangement. 
     In particular embodiments, processor  1402  includes hardware for executing instructions, such as those making up a computer program. As an example and not by way of limitation, to execute instructions, processor  1402  may retrieve (or fetch) the instructions from an internal register, an internal cache, memory  1404 , or storage  1406 ; decode and execute them; and then write one or more results to an internal register, an internal cache, memory  1404 , or storage  1406 . In particular embodiments, processor  1402  may include one or more internal caches for data, instructions, or addresses. This disclosure contemplates processor  1402  including any suitable number of any suitable internal caches, where appropriate. As an example and not by way of limitation, processor  1402  may include one or more instruction caches, one or more data caches, and one or more translation lookaside buffers (TLBs). Instructions in the instruction caches may be copies of instructions in memory  1404  or storage  1406 , and the instruction caches may speed up retrieval of those instructions by processor  1402 . Data in the data caches may be copies of data in memory  1404  or storage  1406  for instructions executing at processor  1402  to operate on; the results of previous instructions executed at processor  1402  for access by subsequent instructions executing at processor  1402  or for writing to memory  1404  or storage  1406 ; or other suitable data. The data caches may speed up read or write operations by processor  1402 . The TLBs may speed up virtual-address translation for processor  1402 . In particular embodiments, processor  1402  may include one or more internal registers for data, instructions, or addresses. This disclosure contemplates processor  1402  including any suitable number of any suitable internal registers, where appropriate. Where appropriate, processor  1402  may include one or more arithmetic logic units (ALUs); be a multi-core processor; or include one or more processors  1402 . Although this disclosure describes and illustrates a particular processor, this disclosure contemplates any suitable processor. 
     In particular embodiments, memory  1404  includes main memory for storing instructions for processor  1402  to execute or data for processor  1402  to operate on. As an example and not by way of limitation, computer system  1400  may load instructions from storage  1406  or another source (such as, for example, another computer system  1400 ) to memory  1404 . Processor  1402  may then load the instructions from memory  1404  to an internal register or internal cache. To execute the instructions, processor  1402  may retrieve the instructions from the internal register or internal cache and decode them. During or after execution of the instructions, processor  1402  may write one or more results (which may be intermediate or final results) to the internal register or internal cache. Processor  1402  may then write one or more of those results to memory  1404 . In particular embodiments, processor  1402  executes only instructions in one or more internal registers or internal caches or in memory  1404  (as opposed to storage  1406  or elsewhere) and operates only on data in one or more internal registers or internal caches or in memory  1404  (as opposed to storage  1406  or elsewhere). One or more memory buses (which may each include an address bus and a data bus) may couple processor  1402  to memory  1404 . Bus  1412  may include one or more memory buses, as described below. In particular embodiments, one or more memory management units (MMUs) reside between processor  1402  and memory  1404  and facilitate accesses to memory  1404  requested by processor  1402 . In particular embodiments, memory  1404  includes random access memory (RAM). This RAM may be volatile memory, where appropriate Where appropriate, this RAM may be dynamic RAM (DRAM) or static RAM (SRAM). Moreover, where appropriate, this RAM may be single-ported or multi-ported RAM. This disclosure contemplates any suitable RAM. Memory  1404  may include one or more memories  1404 , where appropriate. Although this disclosure describes and illustrates particular memory, this disclosure contemplates any suitable memory. 
     In particular embodiments, storage  1406  includes mass storage for data or instructions. As an example and not by way of limitation, storage  1406  may include a hard disk drive (HDD), a floppy disk drive, flash memory, an optical disc, a magneto-optical disc, magnetic tape, or a Universal Serial Bus (USB) drive or a combination of two or more of these. Storage  1406  may include removable or non-removable (or fixed) media, where appropriate. Storage  1406  may be internal or external to computer system  1400 , where appropriate. In particular embodiments, storage  1406  is non-volatile, solid-state memory. In particular embodiments, storage  1406  includes read-only memory (ROM). Where appropriate, this ROM may be mask-programmed ROM, programmable ROM (PROM), erasable PROM (EPROM), electrically erasable PROM (EEPROM), electrically alterable ROM (EAROM), or flash memory or a combination of two or more of these. This disclosure contemplates mass storage  1406  taking any suitable physical form. Storage  1406  may include one or more storage control units facilitating communication between processor  1402  and storage  1406 , where appropriate. Where appropriate, storage  1406  may include one or more storages  1406 . Although this disclosure describes and illustrates particular storage, this disclosure contemplates any suitable storage. 
     In particular embodiments, I/O interface  1408  includes hardware, software, or both, providing one or more interfaces for communication between computer system  1400  and one or more I/O devices. Computer system  1400  may include one or more of these I/O devices, where appropriate. One or more of these I/O devices may enable communication between a person and computer system  1400 . As an example and not by way of limitation, an I/O device may include a keyboard, keypad, microphone, monitor, mouse, printer, scanner, speaker, still camera, stylus, tablet, touch screen, trackball, video camera, another suitable I/O device or a combination of two or more of these. An I/O device may include one or more sensors. This disclosure contemplates any suitable I/O devices and any suitable I/O interfaces  1408  for them. Where appropriate, I/O interface  1408  may include one or more device or software drivers enabling processor  1402  to drive one or more of these I/O devices. I/O interface  1408  may include one or more I/O interfaces  1408 , where appropriate. Although this disclosure describes and illustrates a particular I/O interface, this disclosure contemplates any suitable I/O interface. 
     In particular embodiments, communication interface  1410  includes hardware, software, or both providing one or more interfaces for communication (such as, for example, packet-based communication) between computer system  1400  and one or more other computer systems  1400  or one or more networks. As an example and not by way of limitation, communication interface  1410  may include a network interface controller (NIC) or network adapter for communicating with an Ethernet or other wire-based network or a wireless NIC (WNIC) or wireless adapter for communicating with a wireless network, such as a WI-FI network. This disclosure contemplates any suitable network and any suitable communication interface  1410  for it. As an example and not by way of limitation, computer system  1400  may communicate with an ad hoc network, a personal area network (PAN), a local area network (LAN), a wide area network (WAN), a metropolitan area network (MAN), or one or more portions of the Internet or a combination of two or more of these. One or more portions of one or more of these networks may be wired or wireless. As an example, computer system  1400  may communicate with a wireless PAN (WPAN) (such as, for example, a BLUETOOTH WPAN), a WI-FI network, a WI-MAX network, a cellular telephone network (such as, for example, a Global System for Mobile Communications (GSM) network), or other suitable wireless network or a combination of two or more of these. Computer system  1400  may include any suitable communication interface  1410  for any of these networks, where appropriate. Communication interface  1410  may include one or more communication interfaces  1410 , where appropriate. Although this disclosure describes and illustrates a particular communication interface, this disclosure contemplates any suitable communication interface. 
     In particular embodiments, bus  1412  includes hardware, software, or both coupling components of computer system  1400  to each other. As an example and not by way of limitation, bus  1412  may include an Accelerated Graphics Port (AGP) or other graphics bus, an Enhanced Industry Standard Architecture (EISA) bus, a front-side bus (FSB), a HYPERTRANSPORT (HT) interconnect, an Industry Standard Architecture (ISA) bus, an INFINIBAND interconnect, a low-pin-count (LPC) bus, a memory bus, a Micro Channel Architecture (MCA) bus, a Peripheral Component Interconnect (PCI) bus, a PCI-Express (PCIe) bus, a serial advanced technology attachment (SATA) bus, a Video Electronics Standards Association local (VLB) bus, or another suitable bus or a combination of two or more of these. Bus  1412  may include one or more buses  1412 , where appropriate. Although this disclosure describes and illustrates a particular bus, this disclosure contemplates any suitable bus or interconnect. 
     Herein, a computer-readable non-transitory storage medium or media may include one or more semiconductor-based or other integrated circuits (ICs) (such, as for example, field-programmable gate arrays (FPGAs) or application-specific ICs (ASICs)), hard disk drives (HDDs), hybrid hard drives (HHDs), optical discs, optical disc drives (ODDs), magneto-optical discs, magneto-optical drives, floppy diskettes, floppy disk drives (FDDs), magnetic tapes, solid-state drives (SSDs), RAM-drives, SECURE DIGITAL cards or drives, any other suitable computer-readable non-transitory storage media, or any suitable combination of two or more of these, where appropriate. A computer-readable non-transitory storage medium may be volatile, non-volatile, or a combination of volatile and non-volatile, where appropriate. 
     Miscellaneous 
     Herein, “or” is inclusive and not exclusive, unless expressly indicated otherwise or indicated otherwise by context. Therefore, herein, “A or B” means “A, B, or both,” unless expressly indicated otherwise or indicated otherwise by context. Moreover, “and” is both joint and several, unless expressly indicated otherwise or indicated otherwise by context. Therefore, herein, “A and B” means “A and B, jointly or severally,” unless expressly indicated otherwise or indicated otherwise by context. 
     The scope of this disclosure encompasses all changes, substitutions, variations, alterations, and modifications to the example embodiments described or illustrated herein that a person having ordinary skill in the art would comprehend. The scope of this disclosure is not limited to the example embodiments described or illustrated herein. Moreover, although this disclosure describes and illustrates respective embodiments herein as including particular components, elements, functions, operations, or steps, any of these embodiments may include any combination or permutation of any of the components, elements, functions, operations, or steps described or illustrated anywhere herein that a person having ordinary skill in the art would comprehend. Furthermore, reference in the appended claims to an apparatus or system or a component of an apparatus or system being adapted to, arranged to, capable of, configured to, enabled to, operable to, or operative to perform a particular function encompasses that apparatus, system, component, whether or not it or that particular function is activated, turned on, or unlocked, as long as that apparatus, system, or component is so adapted, arranged, capable, configured, enabled, operable, or operative.