Abstract:
A method, apparatus, system, and storage medium that, in an embodiment, create an index for pages based on association scores for the pages with respect to geographic regions, where the association scores indicate relative degrees to which the pages are associated with the geographic regions. In an embodiment, the association scores are determined by adding a term scare to the association score if a term that is associated with the geographic region is present in the page. The term score indicates a relative degree to which presence of the term in the page indicates that the page is associated with the geographic region. In an embodiment, the association scores are further increased based on association scores of neighbor geographic regions and based on the association scores of incoming linked pages.

Description:
FIELD 
   An embodiment of the invention generally relates to computers. In particular, an embodiment of the invention generally relates to creating an index for the searching of pages based on associations that the pages have with geographic regions. 
   BACKGROUND 
   The development of the EDVAC computer system of 1948 is often cited as the beginning of the computer era. Since that time, computer systems have evolved into extremely sophisticated devices, and computer systems may be found in many different settings. Computer systems typically include a combination of hardware, such as semiconductors and circuit boards, and software, also known as computer programs. As advances in semiconductor processing and computer architecture push the performance of the computer hardware higher, more sophisticated and complex computer software has evolved to take advantage of the higher performance of the hardware, resulting in computer systems today that are much more powerful than just a few years ago. 
   Years ago, computers were isolated devices that did not communicate with each other. But, today computers are often connected in networks, such as the Internet or World Wide Web, and a user at one computer, often called a client, may wish to access information at multiple other computers, often called servers, via a network. Searching is the primary mechanism used to retrieve information from the Internet. Users typically search the web pages of the Internet using a search engine, such as AltaVista, Yahoo, or Google. These search engines index hundreds of millions of web pages and respond to tens of millions of queries every day. 
   To accomplish this formidable task, search engines typically employ three major elements. The first is an agent, often called a spider, robot, or crawler. The crawler visits a web page, reads it, and then follows links to other pages within the site. The crawler typically returns to the site on a regular basis, such as every month or two, to look for changes. The crawler stores the information it finds in the second part of the search engine, which is the index. Sometimes new pages or changes that the crawler finds may take some time to be added to the index. Thus, a web page may have been “crawled” but not yet “indexed.” Until the web page has been added to the index, the web page is not available to those searching with the search engine. Search engine software is the third part of a search engine. This is the program that interrogates the millions of pages recorded in the pre-created index to find matches to a search and ranks them in order of what the program believes is most popular, which is often referred to as the page rank. Page rank is extremely important to the user because a simple search using common terms may match thousands or even tens of thousands of pages, which would be virtually impossible for the user to individually sort through in an attempt to determine which pages best serves the user&#39;s needs. 
   In order to aid the user, search engines typically determine relevancy by following a set of rules, which are commonly known as a page-ranking algorithm. Exactly how a particular search engine&#39;s algorithm works is usually a closely-kept trade secret. But, all major search engines follow the same generally-accepted methods described below. One of the main methods in a page-ranking algorithm involves the location and frequency of keywords on a web page, which is known as the location/frequency method. For example, page-ranking algorithms often assume that terms appearing in a title control-tag are more relevant than terms appearing in other locations in the page. Further, many page-ranking algorithms will also determine if the search keywords appear near the top of a web page, such as in the headline or in the first few paragraphs of text. They assume that any page relevant to the topic will mention those words at the beginning. Frequency of terms is the other major factor that page-ranking algorithms use to determine relevancy. The page-ranking algorithm analyzes how often keywords appear in relation to other words in a web page and deems more relevant those with a higher frequency. 
   In addition to the location/frequency method, which is an on-the-page ranking criteria, search engines also typically make use of off-the-page ranking criteria. Off-the-page criteria are those that use data external to the page itself. Chief among these is link analysis. By analyzing how pages link to each other, the page-ranking algorithm attempts to determine the relative importance of the page with respect to other pages. For example, page-ranking algorithms typically assume that a page to which many other pages link is an important page and deserves to have a high page rank. In addition, some page-ranking algorithms use recursive page-ranking where the rank of the pages that link to the linked-to page also factor into the ranking of the linked-to page. 
   A problem with link analysis occurs with searches that attempt to find pages that are local to a particular area, such as a city. For example, when a user enters search terms for a service (e.g., a home builder, a plumber, or a real estate agent) and a city name, the pages with a high page rank are often not local to the searched-for city. For example, the first pages returned are not those for home builders who have an address within the city. Instead, the pages with a high page rank are referral services that merely mention the searched-for city, along with many other cities, and advertise that the referral service can recommend a home builder in the searched-for city. These referral service pages have a high page ranking because they are partners with many services around the country or around the world, who all link to the referral-service page. These many cross links cause the referral service to have a high page ranking that dominates any page ranking that the local service might have. 
   Thus, a need exists for a better technique for searching pages that are local to an area. 
   SUMMARY 
   A method, apparatus, system, and signal-bearing medium are provided that, in an embodiment, create an index for pages based on association scores for the pages with respect to geographic regions, where the association scores indicate relative degrees to which the pages are associated with the geographic regions. In an embodiment, the association scores are determined by adding a term score to the association score if a term that is associated with the geographic region is present in the page. The term score indicates a relative degree to which presence of the term in the page indicates that the page is associated with the geographic region. In an embodiment, the association scores are further increased based on association scores of neighbor geographic regions and based on the association scores of incoming linked pages. The index is created by selecting keywords that are present in the page, selecting weights for the keywords, finding the keywords that match the terms, and increasing the weights for the keywords that match the terms based on the association scores and the term scores. In this way, a search for a keyword may order the matching pages based on the weights, which are based on the degree to which the matching pages are associated with a geographic region. 

   
     BRIEF DESCRIPTION OF THE DRAWING 
       FIG. 1  depicts a block diagram of an example system for implementing an embodiment of the invention. 
       FIG. 2  depicts a block diagram of an example index, according to an embodiment of the invention. 
       FIG. 3  depicts a block diagram of an example geographic region list, according to an embodiment of the invention. 
       FIG. 4  depicts a flowchart of example processing for creating an index for pages based on association scores and term scores, according to an embodiment of the invention. 
       FIG. 5  depicts a flowchart of example processing for determining an initial association score, according to an embodiment of the invention. 
       FIG. 6  depicts a flowchart of example processing for a search engine, according to an embodiment of the invention. 
   

   DETAILED DESCRIPTION 
   Referring to the Drawings, wherein like numbers denote like parts throughout the several views,  FIG. 1  depicts a high-level block diagram representation of a computer system  100  connected to a client  132  and servers  135  via a network  130 , according to an embodiment of the present invention. The use of “clients” and “servers” are for convenience only, and a computer system that acts as a client in one scenario may act as a server in another scenario, and vice versa. The major components of the computer system  100  include one or more processors  101 , a main memory  102 , a terminal interface  111 , a storage interface  112 , an I/O (Input/Output) device interface  113 , and communications/network interfaces  114 , all of which are coupled for inter-component communication via a memory bus  103 , an I/O bus  104 , and an I/O bus interface unit  105 . 
   The computer system  100  contains one or more general-purpose programmable central processing units (CPUs)  101 A,  101 B,  101 C, and  101 D, herein generically referred to as a processor  101 . In an embodiment, the computer system  100  contains multiple processors typical of a relatively large system; however, in another embodiment the computer system  100  may alternatively be a single CPU system. Each processor  101  executes instructions stored in the main memory  102  and may include one or more levels of on-board cache. 
   The main memory  102  is a random-access semiconductor memory for storing data and programs. The main memory  102  is conceptually a single monolithic entity, but in other embodiments the main memory  102  is a more complex arrangement, such as a hierarchy of caches and other memory devices. For example, memory may exist in multiple levels of caches, and these caches may be further divided by function, so that one cache holds instructions while another holds non-instruction data, which is used by the processor or processors. Memory may further be distributed and associated with different CPUs or sets of CPUs, as is known in any of various so-called non-uniform memory access (NUMA) computer architectures. 
   The memory  102  includes a crawler  150 , a search engine  152 , a geographic region list  154 , and an index  156 . Although the crawler  150 , the search engine  152 , the geographic region list  154 , and the index  156  are illustrated as being contained within the memory  102  in the computer system  100 , in other embodiments some or all of them may be on different computer systems and may be accessed remotely, e.g., via the network  130 . The computer system  100  may use virtual addressing mechanisms that allow the programs of the computer system  100  to behave as if they only have access to a large, single storage entity instead of access to multiple, smaller storage entities. Thus, while the crawler  150 , the search engine  152 , the geographic region list  154 , and the index  156  are illustrated as being contained within the main memory  102 , these elements are not necessarily all completely contained in the same storage device at the same time. 
   In an embodiment, the crawler  150  and/or the search engine  152  include instructions capable of executing on the processor  101  or statements capable of being interpreted by instructions executing on the processor  101  to perform the functions as further described below with reference to  FIGS. 4 ,  5 , and  6 . In another embodiment, the crawler  150  and/or the search engine  152  may be implemented in microcode. In another embodiment, the crawler  150  and/or the search engine  152  may be implemented in hardware via logic gates and/or other appropriate hardware techniques. 
   The geographic region list  154  includes information about geographic regions. The geographic region list  154  is further described below with reference to  FIG. 3 . The index  156  represents the pages  138 . The index  156  is further described below with reference to  FIG. 2 . The crawler  150  builds the index  156  by retrieving the pages  138 , examining their contents, and comparing their contents to the geographic region list  154 . The search engine  152  searches for the pages  138  via the index  156  in response to keywords received from the clients  132 . 
   The memory bus  103  provides a data communication path for transferring data among the processor  101 , the main memory  102 , and the I/O bus interface unit  105 . The I/O bus interface unit  105  is further coupled to the system I/O bus  104  for transferring data to and from the various I/O units. The I/O bus interface unit  105  communicates with multiple I/O interface units  111 ,  112 ,  113 , and  114 , which are also known as I/O processors (IOPs) or I/O adapters (IOAs), through the system I/O bus  104 . The system I/O bus  104  may be, e.g., an industry standard PCI bus, or any other appropriate bus technology. 
   The I/O interface units support communication with a variety of storage and I/O devices. For example, the terminal interface unit  111  supports the attachment of one or more user terminals  121 ,  122 ,  123 , and  124 . The storage interface unit  112  supports the attachment of one or more direct access storage devices (DASD)  125 ,  126 , and  127  (which are typically rotating magnetic disk drive storage devices, although they could alternatively be other devices, including arrays of disk drives configured to appear as a single large storage device to a host). The contents of the main memory  102  may be stored to and retrieved from the direct access storage devices  125 ,  126 , and  127 . 
   The I/O device interface  113  provides an interface to any of various other input/output devices or devices of other types. Two such devices, the printer  128  and the fax machine  129 , are shown in the exemplary embodiment of  FIG. 1 , but in other embodiment many other such devices may exist, which may be of differing types. The network interface  114  provides one or more communications paths from the computer system  100  to other digital devices and computer systems; such paths may include, e.g., one or more networks  130 . 
   Although the memory bus  103  is shown in  FIG. 1  as a relatively simple, single bus structure providing a direct communication path among the processors  101 , the main memory  102 , and the I/O bus interface  105 , in fact the memory bus  103  may comprise multiple different buses or communication paths, which may be arranged in any of various forms, such as point-to-point links in hierarchical, star or web configurations, multiple hierarchical buses, parallel and redundant paths, etc. Furthermore, while the I/O bus interface  105  and the I/O bus  104  are shown as single respective units, the computer system  100  may in fact contain multiple I/O bus interface units  105  and/or multiple I/O buses  104 . While multiple I/O interface units are shown, which separate the system I/O bus  104  from various communications paths running to the various I/O devices, in other embodiments some or all of the I/O devices are connected directly to one or more system I/O buses. 
   The computer system  100  depicted in  FIG. 1  has multiple attached terminals  121 ,  122 ,  123 , and  124 , such as might be typical of a multi-user “mainframe” computer system. Typically, in such a case the actual number of attached devices is greater than those shown in  FIG. 1 , although the present invention is not limited to systems of any particular size. The computer system  100  may alternatively be a single-user system, typically containing only a single user display and keyboard input, or might be a server or similar device which has little or no direct user interface, but receives requests from other computer systems (clients). In other embodiments, the computer system  100  may be implemented as a personal computer, portable computer, laptop or notebook computer, PDA (Personal Digital Assistant), tablet computer, pocket computer, or any other appropriate type of electronic device. 
   The network  130  may be any suitable network or combination of networks and may support any appropriate protocol suitable for communication of data and/or code to/from the computer system  100 . In various embodiments, the network  130  may represent a storage device or a combination of storage devices, either connected directly or indirectly to the computer system  100 . In an embodiment, the network  130  may support Infiniband. In another embodiment, the network  130  may support wireless communications. In another embodiment, the network  130  may support hard-wired communications, such as a telephone line or cable. In another embodiment, the network  130  may support the Ethernet IEEE (Institute of Electrical and Electronics Engineers) 802.3x specification. In another embodiment, the network  130  may be the Internet and may support IP (Internet Protocol). In another embodiment, the network  130  may be a local area network (LAN) or a wide area network (WAN). In another embodiment, the network  130  may be a hotspot service provider network. In another embodiment, the network  130  may be an intranet. In another embodiment, the network  130  may be a GPRS (General Packet Radio Service) network. In another embodiment, the network  130  may be a FRS (Family Radio Service) network. In another embodiment, the network  130  may be any appropriate cellular data network or cell-based radio network technology. In another embodiment, the network  130  may be an IEEE 802.11B wireless network. In still another embodiment, the network  130  may be any suitable network or combination of networks. Although one network  130  is shown, in other embodiments any number (including zero) of networks (of the same or different types) may be present. 
   The client  132  includes an application  136 . The application  136  sends search requests with keywords to the search engine  152 . In an embodiment, the application  136  may be implemented via a browser, but in other embodiments any appropriate application  136  may be used. The servers  135  include pages  138 . The pages  138  may include any appropriate content that is capable of being searched via the search engine  152 . In various embodiments, the pages  138  may be implemented via documents, files, objects, tables, databases, directories, subdirectories, or any portion or combination thereof and in some embodiments may include embedded control tags, statements, or logic. The client  132  and the servers  135  may also include any or all of the hardware and/or software elements previously described above for the computer system  100 . 
   It should be understood that  FIG. 1  is intended to depict the representative major components of the computer system  100 , the network  130 , the client  132 , and the servers  135  at a high level, that individual components may have greater complexity than that represented in  FIG. 1 , that components other than or in addition to those shown in  FIG. 1  may be present, and that the number, type, and configuration of such components may vary. Several particular examples of such additional complexity or additional variations are disclosed herein; it being understood that these are by way of example only and are not necessarily the only such variations. 
   The various software components illustrated in  FIG. 1  and implementing various embodiments of the invention may be implemented in a number of manners, including using various computer software applications, routines, components, programs, objects, modules, data structures, etc., referred to hereinafter as “computer programs,” or simply “programs.” The computer programs typically comprise one or more instructions that are resident at various times in various memory and storage devices in the computer system  100 , and that, when read and executed by one or more processors  101  in the computer system  100 , cause the computer system  100  to perform the steps necessary to execute steps or elements comprising the various aspects of an embodiment of the invention. 
   Moreover, while embodiments of the invention have and hereinafter will be described in the context of fully functioning computer systems, the various embodiments of the invention are capable of being distributed as a program product in a variety of forms, and the invention applies equally regardless of the particular type of signal-bearing medium used to actually carry out the distribution. The programs defining the functions of this embodiment may be delivered to the computer system  100  via a variety of signal-bearing media, which include, but are not limited to: 
   (1) information permanently stored on a non-rewriteable storage medium, e.g., a read-only memory device attached to or within a computer system, such as a CD-ROM readable by a CD-ROM drive; 
   (2) alterable information stored on a rewriteable storage medium, e.g., a hard disk drive (e.g., DASD  125 ,  126 , or  127 ) or diskette; or 
   (3) information conveyed to the computer system  100  by a communications medium, such as through a computer or a telephone network, e.g., the network  130 . 
   Such tangible signal-bearing media, when carrying machine-readable instructions that direct the functions of the present invention, represent embodiments of the present invention. 
   In addition, various programs described hereinafter may be identified based upon the application for which they are implemented in a specific embodiment of the invention. But, any particular program nomenclature that follows is used merely for convenience, and thus embodiments of the invention should not be limited to use solely in any specific application identified and/or implied by such nomenclature. 
   The exemplary environments illustrated in  FIG. 1  are not intended to limit the present invention. Indeed, other alternative hardware and/or software environments may be used without departing from the scope of the invention. 
     FIG. 2  depicts a block diagram of an example data structure for the index  156 , according to an embodiment of the invention. The index  156  includes an address  205 , a keyword list  210 , and a page rank  215  for each page  138 . The keyword list  210  includes a list of keyword entries  220  for each keyword in the page  138 . Each keyword entry  220  includes a keyword  225  and keyword weight  230 . The address  205  includes the URL (Uniform Resource Locator) or other address of the page  138  at the servers  135 . The keyword  225  includes a word or collections of words in the page  138 . The weight  230  indicates the relative weight or importance of the keyword  225 , as compared to other keywords  225 . The page rank  215  indicates a relative importance of the page  138  indicated by the address  205 , as compared to other pages  138 . 
     FIG. 3  depicts a block diagram of an example data structure for the geographic region list  154 , according to an embodiment of the invention. A geographic region list  154  exists for each crawled page  138 . The geographic region list  154  includes geographic regions  305 , an association score  315  for each geographic region  305 , and related terms  320  for each geographic region. The geographic region  305  uniquely identifies a city or other geographic location or area and may include a city, a state, a zip code, a country, or any other appropriate identifying information. The association score  315  indicates the importance, degree, likelihood, or probability that a particular crawled page  138  contains content that is local to, or is associated with, the geographic region  305 . The association score  315  for a crawled page  138  is calculated as further described below with reference to  FIGS. 4 and 5 . 
   The related terms  320  includes a list of term items  325 . Each term item  325  includes a term  330  and a term score  335 . The terms  330  are content (words, numbers, images, or audio) that, if present in a page  138 , tend to indicate that the page  138  also includes other content that is local to, or is associated with, the geographic region  305 . Examples of terms  330  include the name of the geographic region  305 , the zip codes that serve the geographic region  305 , the city, county, state, and/or country in which the geographic region  305  is located, the telephone area code and/or exchanges that serve the geographic region  305 , a nickname or slogan of the geographic region  305 , names of sports teams, names of educational institutions, street names, landmarks, or any other appropriate content. The terms  330  may include words, numbers, or expressions. 
   The term score  335  for an associated term  330  indicates the relative degree, importance, likelihood, or probability (relative to other of the terms  330 ) that the presence of the associated term  330  in the page  138  tends to indicate that the page  138  also includes other content that is associated with the geographic region  305 . For example, a page  138  that includes a telephone number of a specific person may be more likely (and thus has a higher term score  335 ) to also include content associated with the geographic region  305  than a page that only includes the name of the geographic region  305 . 
   In an embodiment, the terms  330  and their term scores  335  are predetermined by the designer of the geographic region list  154 , the designer of the crawler  150 , the designer of the search engine  152 , the designer of the application  136 , or via any appropriate technique. 
     FIG. 4  depicts a flowchart of example processing for crawling the pages  138 , creating an index  156  for the crawled pages  138  based on association scores  315  and term scores  335  according to an embodiment of the invention. The processing of  FIG. 4  is performed periodically, so that the crawler  150  may crawl and process pages  138  that have been added or modified since the last time that the crawler  150  crawled the pages  138 . 
   Control begins at block  400 . Control then continues to block  405  where the crawler  150  enters a loop that is executed once for each page  138 . The crawler  150  may crawl all pages  138  or a subset of the pages  138 . So long as more pages  138  remain to be crawled, control continues from block  405  to block  410  where the crawler  150  retrieves the current page  138  from a server  135 . Control then continues to block  415  where the crawler  150  determines the initial association scores  315  for all geographic regions  305  in the geographic region list  154  that is associated with the current page  138 , as further described below with reference to  FIG. 5 . 
   Control then continues to block  420  where the crawler  150  adds the current page  138  to the index  156 . Adding the current page  138  to the index  156  includes storing the address for the current page  138  in the address  205 , storing the terms that exist in the current page  138  into the keywords  225  of the index  156 , and calculating and storing the weights  230  for the terms that exist in the current page  138  into the weights  230  in the index  156 . The crawler  150  may use any appropriate technique for selecting the keywords  225  and the weights  230 . For example, in an embodiment the crawler  150  may choose to ignore short, common words in the page  138  (e.g., “a” “and,” and “the”), and not store these words in the keywords  225 . In an embodiment, the crawler  150  may select the weights  230  based on the location and/or frequency of the selected keywords  225 . For example, the crawler  150  may assign higher weights  230  to those selected keywords  225  that are in the title of the page  150  and assign lower weights  230  to those keywords  225  that are at the bottom of the page  138 . In an embodiment, the crawler  150  may assign higher weights  230  to those keywords  225  that are used more frequently in the page  139  while assigning lower weights  230  to those keywords  225  that are used less frequently in the page  138 . But, in other embodiments, the crawler  150  may used any appropriate technique for selecting the terms from the page  138  to store in the keywords  225  and for selecting the weights  230  for those keywords  225 . Control then returns to block  405  where the crawler  150  determines whether another page  138  exists to be crawled, as previously described above. 
   If the crawler  150  has crawled every page  138 , then control continues from block  405  to block  425  where the crawler  150  calculates the page ranks  215  for every page  138  in the index  156 . In an embodiment, the crawler  150  may use link analysis or any other appropriate technique for calculating all of the page ranks  215  for all the pages  138 . 
   Control then continues to block  430  where the crawler  150  performs a graph algorithm on the index  156  and a graph of the outgoing links for every page in the index, which increases the association score  315  for a page based on the association scores of the pages that link to that page (the inbound links). The crawler  150  further stores the results of the graph algorithm in the association scores  315  for the page. A link is an address of a linked page that is embedded in a linking page that, when selected, causes the linked page to be retrieved. A URL (Uniform Resource Locator) is an example of a link, but in other embodiments any appropriate link may be used. Thus, the crawler  150  propagates the association scores  315  using a graph algorithm to determine the degree of local weighting, taking advantage of the fact that many pages that are from the same community link to other sites within the same community. For example, a local builder may link to the local lumberyard, the local plumber, the local electrician, and the local real estate agent, and the local builder may be linked to by the local Chamber of Commerce and the local builder&#39;s trade association. By determining how well a page is linked to by other pages that are also local to the community, an embodiment of the invention modifies the initial content-based association score  315  that was created by the processing of  FIG. 5  to produce a new association score  315  for each geographic region. 
   In an embodiment, to determine the propagated association scores  315  for a page “A,” all of the inbound links to the page A are utilized via the following example formulas:
 
 AS ( A,g   1 )=( AS ( t   1   ,g   1 )/ O ( t   1 )+ . . . + AS ( t   n   ,g   1 )/ O ( t   n ))
 
 AS ( A,g   m )=( AS ( t   1   ,g   m )/ O ( t   1 )+ . . . + AS ( t   n   ,g   m )/ O ( t   n ))
 
   where: 
   t 1 -t n  are the pages  138  that link to page A, i.e., pages t 1 -t f  are the inbound links to the page A; 
   O is the number of outbound links that the pages t 1 -t n  include; 
   g 1 -g m  are all possible geographic regions  305  that have an association score AS  315 ; and 
   AS(A,g j ) is the association score  315  for the page A based on a geographic region g j , where j=1 to m. That is, AS(A,g j ) is the likelihood, probability, strength, or degree to which the page A is local to, or is associated with, the geographic region g j . Similarly, AS(t i ,g j ) is the association score  315  for the page t i  based on a geographic region g j , where i=1 to n and j=1 to m. 
   Control then continues to block  435  where the crawler  150  finds the keywords  225  in the index  156  that match (are equal to) the terms  330  in the geographic region list  154 . Control then continues to block  440  where the controller increases the weights  230  of the found keywords  225  based on the association score  315  of the geographic region  305  that has the matching terms  330  and based on the term scores  335  of the matching terms  330 . In an embodiment, the crawler  150  increases the weights  230  of the found keywords  225  via the following example calculation:
 
 W=W +[( T/M )*( A/S )* W ], where
 
   W is the weight  230  of the keyword  225  that matches the term  330 ; 
   T is the term score  335  of the matching term  330 ; 
   M is the maximum term score  335  in the geographic region list  154  associated with the page  138  that contains the matching keywords  225 ; 
   A is the association score  315  of the geographic region  305  that has the matching term  330 ; and 
   S is the sum of the term scores  335  in the geographic region list  154  for the matching term  330 . 
   Control then continues to block  499  where the logic of  FIG. 4  returns. 
     FIG. 5  depicts a flowchart of example processing for determining an initial association score  315  for all geographic regions  305  in the geographic region list  154  that are associated with the current page  138 , according to an embodiment of the invention. The current page  138  is passed to the logic of  FIG. 5  by the invoker of the logic of  FIG. 5 , as previously described above with reference to  FIG. 4 . 
   Control begins at block  500 . Control then continues to block  505  where the crawler  150  enters a loop that is executed once for each geographic region  305  in the geographic region list  154 . So long as more geographic regions  305  remain to be processed, control continues from block  505  to block  510  where the crawler  150  enters a loop executed once for each term  330  associated with the current geographic region  305 . So long as more terms associated with the current geographic region  305  remain to be processed, control continues from block  510  to block  515  where the crawler  150  determines whether the current term  330  is present in the current page  138 . 
   If the determination at block  515  is true, then the current term  330  is present in the current page  138 , so control continues to block  520  where the crawler  150  adds the term score  335  for the current term  330  that was found in the current page  138  to the association score  315  for the current geographic region  305 . Control then returns to block  510  where the crawler  150  sets the current term  330  to be the next term  330  associated with the current geographic region  305  and determines whether all terms  330  associated with the current geographic region  305  have been processed by the loop, as previously described above. 
   If the determination at block  515  is false, then the current term  330  is not present in the current page  138 , so control returns from block  515  to block  510  where the crawler  150  sets the current term  330  to be the next term  330  associated with the current geographic region  305  and determines whether all terms associated with the current geographic region  305  have been processed, as previously described above. 
   When all terms associated with the current geographic region  305  have been processed, then the loop that starts at block  510  is done, so control returns from block  510  to block  505  where the crawler  150  sets the current geographic region  305  to be the next geographic region  305  in the geographic region list  154  and determines whether the current geographic region  305  remains to be processed, as previously described above. 
   When all geographic regions  305  in the geographic region list  154  have been processed, then the loop that starts at block  505  is done, so control continues from block  505  to block  525  where the crawler  150  enters a loop that is executed once for each geographic region  305  in the geographic region list  154 . So long as more geographic regions  305  remain to be processed, control continues from block  525  to block  530  where the crawler  150  determines whether the association score  315  for the current geographic region  305  is greater than zero. 
   If the determination at block  530  is true, then the association score  315  for the current geographic region  305  is greater than zero, so control continues from block  530  to block  535  where the crawler  150  starts a loop for each neighbor geographic region  305  of the current geographic region  305 . In various embodiments, geographic regions  305  are neighbors if they are within a threshold distance of each other, within a threshold travel time, in the same zip code or delivery zone, on the same street or highway, in the same county, in the same time zone, in the same state, have the same telephone area code, have the same telephone area code and exchange, or any other appropriate criteria. So long as a next neighbor geographic region  305  exists for the current geographic region  305 , control continues from block  535  to block  540  where the crawler  150  determines whether the association score  315  of the current neighbor geographic region  305  of the current geographic region  305  is greater than zero. 
   If the determination at block  540  is true, then the association score  315  of the current neighbor geographic region  305  is greater than zero, so control continues from block  540  to block  545  where the crawler  150  increases the association score  315  of the current geographic region  305 . In an embodiment, the crawler  150  adds the association score  315  of the current neighbor geographic region  305  to the association score of the current geographic region  305 , but in other embodiments, the crawler  150  may increase the association score  315  of the current geographic region  305  by any appropriate amount. Control then returns to block  535  where the crawler  150  sets the current neighbor geographic region  305  to be the next neighbor geographic region  305  and determines whether all neighbor geographic regions  305  have been processed, as previously described above. 
   If the determination at block  540  is false, then the association score  315  of the current neighbor geographic region  305  is not greater than zero, so control returns from block  540  to block  535 , as previously describe above. 
   When all neighbor geographic regions  305  of the current geographic region  305  have been processed, then the loop that starts at block  535  is done, so control returns from block  535  to block  525  where the crawler  150  sets the current geographic region  305  to be the next geographic region  305  in the geographic region list  154  and determines whether all geographic regions  305  have been processed by the loop that starts at block  525 , as previously described above. 
   If the determination at block  530  is false then the association score  315  of the current neighbor geographic region  305  to the current geographic region  305  is not greater than zero, so control returns to block  525 , as previously described above. 
   When all geographic regions  305  in the geographic region list  154  have been processed by the loop that starts at block  525 , then the loop that starts at block  525  is done, so control continues from block  525  to block  599  where the logic of  FIG. 5  returns. 
     FIG. 6  depicts a flowchart of example processing for the search engine  152 , according to an embodiment of the invention. Control begins at block  600 . Control then continues to block  605  where the search engine  152  receives a search keyword from the application  136  at the client  132 . Control then continues to block  610  where the search engine  152  enters a loop that executes once for each page  138  in the index  156  with a keyword  225  that matches (equals) the received search keyword. So long as a page  138  exists in the index  156  with a keyword  225  that matches the received search keyword, control continues from block  610  to block  615  where the search engine  152  sets a total for the current page  138  to zero. 
   Control then continues to block  620  where the search engine  152  enters a loop that executes once for each matching keyword  225  (that matches the received search keyword) in the current page  138 . So long as a keyword  225  exists for the current page  138  that matches the received search keyword, control continues from block  620  to block  625  where the search engine  152  sets the total to be the total plus the weight  230  for the current matching keyword  225 . Control then returns to block  620  where the search engine  152  sets the current matching keyword  225  to be the next matching keyword  225  in the current page  138  and determines whether all matching keywords  225  in the current page  138  have been processed. 
   When all matching keywords  225  for the current page  138  have been processed, the loop that starts at block  620  is done, so control continues form block  620  to block  630  where the search engine  152  sets the match score to be the total that was calculated by the loop that started at block  620  multiplied by the page rank  215  for the current page  138 . Control then continues to block  635  where the search engine  152  determines whether the match score is greater than a match threshold. 
   If the determination at block  635  is true, then the match score is greater than a match threshold, so control continues from block  635  to block  640  where the search engine  152  adds the current page  138  to the matching search results, ordered by the match score. Control then returns to block  610  where the search engine  152  changes the current page  138  to be the next page  138  in the index  156  with a keyword  225  that matches the received search keyword, and determines whether all pages  138  with matching keywords  225  have been processed, as previously described above. 
   If the determination at block  635  is false, then the match score is not greater than the match threshold, so control returns from block  635  to block  610 , as previously described above. 
   When all pages  138  in the index  156  with a keyword  225  that matches the received keyword have been processed by the loop that starts at block  610 , then the loop that starts at block  610  is done, so control continues form block  645  where the search engine  152  displays the matching search results in the order specified by the match score. In an embodiment, the search engine  152  displays the matching search results by sending the matching search results to the application  136  at the client  132 , which displays the matching search results. Control then continues to block  699  where the logic of  FIG. 6  returns. 
   In the previous detailed description of exemplary embodiments of the invention, reference was made to the accompanying drawings (where like numbers represent like elements), which form a part hereof, and in which is shown by way of illustration specific exemplary embodiments in which the invention may be practiced. These embodiments were described in sufficient detail to enable those skilled in the art to practice the invention, but other embodiments may be utilized and logical, mechanical, electrical, and other changes may be made without departing from the scope of the present invention. Different instances of the word “embodiment” as used within this specification do not necessarily refer to the same embodiment, but they may. Any data and data structures illustrated or described herein are examples only, and in other embodiments, different amounts of data, types of data, fields, numbers and types of fields, field names, numbers and types of records, entries, or organizations of data may be used. In addition, any data may be combined with logic, so that a separate data structure is not necessary. The previous detailed description is, therefore, not to be taken in a limiting sense, and the scope of the present invention is defined only by the appended claims. 
   In the previous description, numerous specific details were set forth to provide a thorough understanding of the invention. But, the invention may be practiced without these specific details. In other instances, well-known circuits, structures, and techniques have not been shown in detail in order not to obscure the invention.