Query language

[0001] This application is related to the following U.S. applications, all of which are incorporated by reference herein:

[0002] U.S. application Ser. No. ______, entitled “Support for Object Search”, filed concurrently herewith, by Alex Kehlenbeck, Andrew W. Hogue, Jonathan T. Betz, Attorney Docket No. 24207-10945;

[0003] U.S. application Ser. No. ______ entitled “Data Object Visualization”, filed on Jan. 27, 2006, by Andrew W. Hogue, David Vespe, Alex Kehlenbeck, Mike Gordon, Jeffrey C. Reynar, David Alpert, Attorney Docket No. 24207-10946;

[0004] U.S. application Ser. No. ______, entitled “Data Object Visualization Using Maps”, filed on Jan. 27, 2006, by Andrew W. Hogue, David Vespe, Alex Kehlenbeck, Mike Gordon, Jeffrey C. Reynar, David Alpert, Attorney Docket No. 24207-10947;

[0005] U.S. application Ser. No. ______, entitled “Automatic Object Reference Identification and Linking in a Browseable Fact Repository”, filed concurrently herewith, by Andrew W. Hogue, Attorney Docket No. 24207-10961;

[0006] U.S. application Ser. No. ______, entitled “Browseable Fact Repository”, filed concurrently herewith, by Andrew W. Hogue, Jonathan T. Betz, Attorney Docket No. 24207-10949;

[0007] U.S. application Ser. No. ______, entitled “ID Persistence Through Normalization”, filed concurrently herewith, by Jonathan T. Betz, Andrew W. Hogue, Attorney Docket No. 24207-10950;

[0008] U.S. application Ser. No. ______, entitled “Annotation Framework”, filed concurrently herewith, by Tom Richford, Jonathan T. Betz, Attorney Docket No. 24207-10951;

[0009] U.S. application Ser. No. ______, entitled “Object Categorization for Information Extraction”, filed on Jan. 27, 2006, by Jonathan T. Betz, Attorney Docket No. 24207-10952;

[0010] U.S. application Ser. No. ______, entitled “Modular Architecture for Entity Normalization”, filed concurrently herewith, by Jonathan T. Betz, Farhan Shamsi, Attorney Docket No. 24207-10953;

[0011] U.S. application Ser. No. ______, entitled “Attribute Entropy as a Signal in Object Normalization”, filed concurrently herewith, by Jonathan T. Betz, Vivek Menezes, Attorney Docket No. 24207-10954;

[0012] U.S. application Ser. No. ______, entitled “Designating Data Objects for Analysis”, filed on Jan. 27, 2006, by Andrew W. Hogue, David Vespe, Alex Kehlenbeck, Mike Gordon, Jeffrey C. Reynar, David Alpert, Attorney Docket No. 24207-11126;

[0013] U.S. application Ser. No. ______, entitled “Data Object Visualization Using Graphs”, filed on Jan. 27, 2006, by Andrew W. Hogue, David Vespe, Alex Kehlenbeck, Mike Gordon, Jeffrey C. Reynar, David Alpert, Attorney Docket No. 24207-11125.

[0014] 1. Field of the Invention

[0015] This invention pertains in general to searching collections of data and, in particular, to ways of querying such collections of data.

[0016] 2. Description of the Related Art

[0017] The World Wide Web and other information storage and retrieval systems contain a great deal of information. With the advent of search engines and other similar tools it has become relatively easy for an end-user to locate particular information. For example, one can obtain a wealth of information about “elemental particles” by simply searching for the terms “elemental particles” on the Web. This search can be accomplished using one or both of a graphical search engine or a text-based search engine.

[0018] Many search engines exist to search the World Wide Web. The Google search engine, for example, employs a user-friendly syntax that lets users simply type in a search query for items of interest (e.g., typing “Britney Spears” to find out information about the singer Britney Spears). The Google search engine also allows users to construct more complex search queries. For example, advanced Google search allows users to search for web pages by specifying that the web page: a) must contain an exact phrase (by placing the query terms in quotes); b) must contain one or more of the query terms, or c) must not contain one or more of the query terms. This advanced search capability allows a user to tailor his search for web pages that contain specific information. Google search permits search of web pages, which are an example of unstructured data.

[0019] Many search engines also exist to search more conventional databases of structured data. For example, the SQL query language allows users to search more conventional structured databases. Such databases usually have data stored in predefined formats and in predefined fields. Thus, an SQL query looks for certain values in predefined fields.

[0020] As the retrieval and storage of information on the Internet continues to evolve, information is being stored in many different formats besides web pages. What is needed are new and advanced ways of searching large collections of data from diverse sources, such as the Internet.

[0021] The described embodiments of the present invention provide a methodology and system for searching facts in a collection of semi-structured data called a fact repository. The fact repository includes a large collection of facts, each of which is associated with an object, such as a person, place, book, movie, country, or any other entity of interest. Each fact comprises an attribute, which is descriptive of the type of fact (e.g., “name,” or “population”), and a value for that attribute (e.g., “George Washington”, or “1,397,264,580”). A value can also contain any amount of text—from a single term or phrase to many paragraphs or pages—such as appropriate to describe the attribute. Each object will have a name fact that is the name of the object. The value of a value can thus include one or more phrases that are themselves the names of other facts.

[0022] The embodiments of the present invention incorporate a query language to search semi-structured data. Although the data is organized into fields including attributes, the user may not know all possible attribute names/types, etc. Because the user is searching semi-structured data (instead of structured data) the user can submit a query even when he does not know what attributes are contained in the repository. Because the user is searching semi-structured data (instead of unstructured data) the user can submit a query over data that has been organized to a certain extent.

[0023] The present invention further has embodiments in computer program products, computer systems, and computer user interfaces, which perform or cooperate in the operation or use of the foregoing method (or its alternative embodiments and features).

[0024] FIG. 1 shows a system architecture, in accordance with a preferred embodiment of the invention.

[0025] FIGS. 2(a)-2(d) are block diagrams illustrating a data structure for facts within a repository of FIG. 1 in accordance with preferred embodiments of the invention.

[0026] FIG. 2(e) is a block diagram illustrating an alternate data structure for facts and objects in accordance with preferred embodiments of the invention.

[0027] FIG. 3(a) illustrates a landing page for initiating a search query of a fact repository

[0028] FIG. 3(b) illustrates a search results page.

[0029] FIG. 3(c) is a flow chart of a method for processing a search query.

[0030] FIG. 4 shows an example of a plurality of facts in a repository of FIG. 1.

[0031] FIG. 5(a)-5(t) illustrate examples of search queries.

[0032] The figures depict a preferred embodiment of the present invention for purposes of illustration only. One skilled in the art will readily recognize from the following discussion that alternative embodiments of the structures and methods illustrated herein may be employed without departing from the principles of the invention described herein.

[0033] FIG. 1 shows a system architecture 100 adapted to support one embodiment of the invention. FIG. 1 shows components used to add facts into, and retrieve facts from a repository 115. The system architecture 100 includes a network 104, through which any number of document hosts 102 communicate with a data processing system 106, along with any number of object requesters 152, 154.

[0034] Document hosts 102 store documents and provide access to documents. A document is comprised of any machine-readable data including any combination of text, graphics, multimedia content, etc. A document may be encoded in a markup language, such as Hypertext Markup Language (HTML), i.e., a web page, in a interpreted language (e.g., JavaScript) or in any other computer readable or executable format. A document can include one or more hyperlinks to other documents. A typical document will include one or more facts within its content. A document stored in a document host 102 may be located and/or identified by a Uniform Resource Locator (URL), or Web address, or any other appropriate form of identification and/or location. A document host 102 is implemented by a computer system, and typically includes a server adapted to communicate over the network 104 via networking protocols (e.g., TCP/IP), as well as application and presentation protocols (e.g., HTTP, HTML, SOAP, D-HTML, Java). The documents stored by a host 102 are typically held in a file directory, a database, or other data repository. A host 102 can be implemented in any computing device (e.g., from a PDA or personal computer, a workstation, mini-computer, or mainframe, to a cluster or grid of computers), as well as in any processor architecture or operating system.

[0035] FIG. 1 shows components used to manage facts in a fact repository 115. Data processing system 106 includes one or more importers 108, one or more janitors 110, a build engine 112, a service engine 114, and a fact repository 115 (also called simply a “repository”). Each of the foregoing are implemented, in one embodiment, as software modules (or programs) executed by processor 116. Importers 108 operate to process documents received from the document hosts, read the data content of documents, and extract facts (as operationally and programmatically defined within the data processing system 106) from such documents. The importers 108 also determine the subject or subjects with which the facts are associated, and extract such facts into individual items of data, for storage in the fact repository 115. In one embodiment, there are different types of importers 108 for different types of documents, for example, dependent on the format or document type.

[0036] Janitors 110 operate to process facts extracted by importer 108. This processing can include but is not limited to, data cleansing, object merging, and fact induction. In one embodiment, there are a number of different janitors 110 that perform different types of data management operations on the facts. For example, one janitor 110 may traverse some set of facts in the repository 115 to find duplicate facts (that is, facts that convey the same factual information) and merge them. Another janitor 110 may also normalize facts into standard formats. Another janitor 110 may also remove unwanted facts from repository 115, such as facts related to pornographic content. Other types of janitors 110 may be implemented, depending on the types of data management functions desired, such as translation, compression, spelling or grammar correction, and the like.

[0037] Various janitors 110 act on facts to normalize attribute names, and values and delete duplicate and near-duplicate facts so an object does not have redundant information. For example, we might find on one page that Britney Spears' birthday is “12/2/1981” while on another page that her date of birth is “Dec. 2, 1981.”Birthday and Date of Birth might both be rewritten as Birthdate by one janitor and then another janitor might notice that 12/2/1981 and Dec. 2, 1981 are different forms of the same date. It would choose the preferred form, remove the other fact and combine the source lists for the two facts. As a result when you look at the source pages for this fact, on some you'll find an exact match of the fact and on others text that is considered to be synonymous with the fact.

[0038] Build engine 112 builds and manages the repository 115. Service engine 114 is an interface for querying the repository 115. Service engine 114's main function is to process queries, score matching objects, and return them to the caller but it is also used by janitor 110.

[0039] Repository 115 stores factual information extracted from a plurality of documents that are located on document hosts 102. A document from which a particular fact may be extracted is a source document (or “source”) of that particular fact. In other words, a source of a fact includes that fact (or a synonymous fact) within its contents.

[0040] Repository 115 contains one or more facts. In one embodiment, each fact is associated with exactly one object. One implementation for this association includes in each fact an object ID that uniquely identifies the object of the association. In this manner, any number of facts may be associated with an individual object, by including the object ID for that object in the facts. In one embodiment, objects themselves are not physically stored in the repository 115, but rather are defined by the set or group of facts with the same associated object ID, as described below. Further details about facts in repository 115 are described below, in relation to FIGS. 2(a)-2(d).

[0041] It should be appreciated that in practice at least some of the components of the data processing system 106 will be distributed over multiple computers, communicating over a network. For example, repository 115 may be deployed over multiple servers. As another example, the janitors 110 may be located on any number of different computers. For convenience of explanation, however, the components of the data processing system 106 are discussed as though they were implemented on a single computer.

[0042] In another embodiment, some or all of document hosts 102 are located on data processing system 106 instead of being coupled to data processing system 106 by a network. For example, importer 108 may import facts from a database that is a part of or associated with data processing system 106.

[0043] FIG. 1 also includes components to access repository 115 on behalf of one or more object requesters 152, 154. Object requesters are entities that request objects from repository 115. Object requesters 152, 154 may be understood as clients of the system 106, and can be implemented in any computer device or architecture. As shown in FIG. 1, a first object requester 152 is located remotely from system 106, while a second object requester 154 is located in data processing system 106. For example, in a computer system hosting a blog, the blog may include a reference to an object whose facts are in repository 115. An object requester 152, such as a browser displaying the blog will access data processing system 106 so that the information of the facts associated with the object can be displayed as part of the blog web page. As a second example, janitor 110 or other entity considered to be part of data processing system 106 can function as object requester 154, requesting the facts of objects from repository 115.

[0044] FIG. 1 shows that data processing system 106 includes a memory 107 and one or more processors 116. Memory 107 includes importers 108, janitors 110, build engine 112, service engine 114, and requester 154, each of which are preferably implemented as instructions stored in memory 107 and executable by processor 116. Memory 107 also includes repository 115. Repository 115 can be stored in a memory of one or more computer systems or in a type of memory such as a disk. FIG. 1 also includes a computer readable medium 118 containing, for example, at least one of importers 108, janitors 110, build engine 112, service engine 114, requester 154, and at least some portions of repository 115. FIG. 1 also includes one or more input/output devices 120 that allow data to be input and output to and from data processing system 106. It will be understood that data processing system 106 preferably also includes standard software components such as operating systems and the like and further preferably includes standard hardware components not shown in the figure for clarity of example.

[0045] FIG. 2(a) shows an example format of a data structure for facts within repository 115, according to some embodiments of the invention. As described above, the repository 115 includes facts 204. Each fact 204 includes a unique identifier for that fact, such as a fact ID 210. Each fact 204 includes at least an attribute 212 and a value 214. For example, a fact associated with an object representing George Washington may include an attribute of “date of birth” and a value of “Feb. 22, 1732.” In one embodiment, all facts are stored as alphanumeric characters since they are extracted from web pages. In another embodiment, facts also can store binary data values. Other embodiments, however, may store fact values as mixed types, or in encoded formats.

[0046] As described above, each fact is associated with an object ID 209 that identifies the object that the fact describes. Thus, each fact that is associated with a same entity (such as George Washington), will have the same object ID 209. In one embodiment, objects are not stored as separate data entities in memory. In this embodiment, the facts associated with an object contain the same object ID, but no physical object exists. In another embodiment, objects are stored as data entities in memory, and include references (for example, pointers or IDs) to the facts associated with the object. The logical data structure of a fact can take various forms; in general, a fact is represented by a tuple that includes a fact ID, an attribute, a value, and an object ID. The storage implementation of a fact can be in any underlying physical data structure.

[0047] FIG. 2(b) shows an example of facts having respective fact IDs of 10, 20, and 30 in repository 115. Facts 10 and 20 are associated with an object identified by object ID “1.” Fact 10 has an attribute of “Name” and a value of “China.” Fact 20 has an attribute of “Category” and a value of “Country.” Thus, the object identified by object ID “1” has a name fact 205 with a value of “China” and a category fact 206 with a value of “Country.” Fact 30 208 has an attribute of “Property” and a value of “Bill Clinton was the 42nd President of the United States from 1993 to 2001.” Thus, the object identified by object ID “2” has a property fact with a fact ID of 30 and a value of “Bill Clinton was the 42nd President of the United States from 1993 to 2001.” In the illustrated embodiment, each fact has one attribute and one value. The number of facts associated with an object is not limited; thus while only two facts are shown for the “China” object, in practice there may be dozens, even hundreds of facts associated with a given object. Also, the value fields of a fact need not be limited in size or content. For example, a fact about the economy of “China” with an attribute of “Economy” would have a value including several paragraphs of text, numbers, perhaps even tables of figures. This content can be formatted, for example, in a markup language. For example, a fact having an attribute “original html” might have a value of the original html text taken from the source web page.

[0048] Also, while the illustration of FIG. 2(b) shows the explicit coding of object ID, fact ID, attribute, and value, in practice the content of the fact can be implicitly coded as well (e.g., the first field being the object ID, the second field being the fact ID, the third field being the attribute, and the fourth field being the value). Other fields include but are not limited to: the language used to state the fact (English, etc.), how important the fact is, the source of the fact, a confidence value for the fact, and so on.

[0049] FIG. 2(c) shows an example object reference table 210 that is used in some embodiments. Not all embodiments include an object reference table. The object reference table 210 functions to efficiently maintain the associations between object IDs and fact IDs. In the absence of an object reference table 210, it is also possible to find all facts for a given object ID by querying the repository to find all facts with a particular object ID. While FIGS. 2(b) and 2(c) illustrate the object reference table 210 with explicit coding of object and fact IDs, the table also may contain just the ID values themselves in column or pair-wise arrangements.

[0050] FIG. 2(d) shows an example of a data structure for facts within repository 115, according to some embodiments of the invention showing an extended format of facts. In this example, the fields include an object reference link 216 to another object. The object reference link 216 can be an object ID of another object in the repository 115, or a reference to the location (e.g., table row) for the object in the object reference table 210. The object reference link 216 allows facts to have as values other objects. For example, for an object “United States,” there may be a fact with the attribute of “president” and the value of “George W. Bush,” with “George W. Bush” being an object having its own facts in repository 115. In some embodiments, the value field 214 stores the name of the linked object and the link 216 stores the object identifier of the linked object. Thus, this “president” fact would include the value 214 of “George W. Bush”, and object reference link 216 that contains the object ID for the for “George W. Bush” object. In some other embodiments, facts 204 do not include a link field 216 because the value 214 of a fact 204 may store a link to another object.

[0051] Each fact 204 also may include one or more metrics 218. A metric provides an indication of the some quality of the fact. In some embodiments, the metrics include a confidence level and an importance level. The confidence level indicates the likelihood that the fact is correct. The importance level indicates the relevance of the fact to the object, compared to other facts for the same object. The importance level may optionally be viewed as a measure of how vital a fact is to an understanding of the entity or concept represented by the object.

[0052] Each fact 204 includes a list of one or more sources 220 that include the fact and from which the fact was extracted. Each source may be identified by a Uniform Resource Locator (URL), or Web address, or any other appropriate form of identification and/or location, such as a unique document identifier.

[0053] The facts illustrated in FIG. 2(d) include an agent field 222 that identifies the importer 108 that extracted the fact. For example, the importer 108 may be a specialized importer that extracts facts from a specific source (e.g., the pages of a particular web site, or family of web sites) or type of source (e.g., web pages that present factual information in tabular form), or an importer 108 that extracts facts from free text in documents throughout the Web, and so forth.

[0054] Some embodiments include one or more specialized facts, such as a name fact 207 and a property fact 208. A name fact 207 is a fact that conveys a name for the entity or concept represented by the object ID. A name fact 207 includes an attribute 224 of “name” and a value, which is the name of the object. For example, for an object representing the country Spain, a name fact would have the value “Spain.” A name fact 207, being a special instance of a general fact 204, includes the same fields as any other fact 204; it has an attribute, a value, a fact ID, metrics, sources, etc. The attribute 224 of a name fact 207 indicates that the fact is a name fact, and the value is the actual name. The name may be a string of characters. An object ID may have one or more associated name facts, as many entities or concepts can have more than one name. For example, an object ID representing Spain may have associated name facts conveying the country's common name “Spain” and the official name “Kingdom of Spain.” As another example, an object ID representing the U.S. Patent and Trademark Office may have associated name facts conveying the agency's acronyms “PTO” and “USPTO” as well as the official name “United States Patent and Trademark Office.” If an object does have more than one associated name fact, one of the name facts may be designated as a primary name and other name facts may be designated as secondary names, either implicitly or explicitly.

[0055] A property fact 208 is a fact that conveys a statement about the entity or concept represented by the object ID. Property facts are generally used for summary information about an object. A property fact 208, being a special instance of a general fact 204, also includes the same parameters (such as attribute, value, fact ID, etc.) as other facts 204. The attribute field 226 of a property fact 208 indicates that the fact is a property fact (e.g., attribute is “property”) and the value is a string of text that conveys the statement of interest. For example, for the object ID representing Bill Clinton, the value of a property fact may be the text string “Bill Clinton was the 42nd President of the United States from 1993 to 2001.” “Some object IDs may have one or more associated property facts while other objects may have no associated property facts. It should be appreciated that the data structures shown in FIGS. 2(a)-2(d) and described above are merely exemplary. The data structure of the repository 115 may take on other forms. Other fields may be included in facts and some of the fields described above may be omitted. Additionally, each object ID may have additional special facts aside from name facts and property facts, such as facts conveying a type or category (for example, person, place, movie, actor, organization, etc.) for categorizing the entity or concept represented by the object ID. In some embodiments, an object's name(s) and/or properties may be represented by special records that have a different format than the general facts records 204.

[0056] As described previously, a collection of facts is associated with an object ID of an object. An object may become a null or empty object when facts are disassociated from the object. A null object can arise in a number of different ways. One type of null object is an object that has had all of its facts (including name facts) removed, leaving no facts associated with its object ID. Another type of null object is an object that has all of its associated facts other than name facts removed, leaving only its name fact(s). Alternatively, the object may be a null object only if all of its associated name facts are removed. A null object represents an entity or concept for which the data processing system 106 has no factual information and, as far as the data processing system 106 is concerned, does not exist. In some embodiments, facts of a null object may be left in the repository 115, but have their object ID values cleared (or have their importance to a negative value). However, the facts of the null object are treated as if they were removed from the repository 115. In some other embodiments, facts of null objects are physically removed from repository 115.

[0057] FIG. 2(e) is a block diagram illustrating an alternate data structure 290 for facts and objects in accordance with preferred embodiments of the invention. In this data structure, an object 290 contains an object ID 292 and references or points to facts 294. Each fact includes a fact ID 295, an attribute 297, and a value 299. In this embodiment, an object 290 actually exists in memory 107.

[0058] Referring again to FIG. 1, the content of the facts in the repository 115 are also indexed in index 127. The index 127 maintains a term index, which maps terms to {object, fact, field, token) tuples, where “field” is, e.g., attribute or value. The service engine 114 is adapted to receive keyword queries from clients such as object requestors, and communicates with the index 127 to retrieve the facts that are relevant to user's search query. For a generic query containing one or more terms, the service engine 114 assumes the scope is at the object level. Thus, any object with one or more of the query terms somewhere (not necessarily on the same fact) will match the query for purposes of being ranked in the search results.

[0059] In one embodiment the ranking (score) of an object is a linear combination of relevance scores for each of the facts. The relevance score for each fact is based on whether the fact includes one or more query terms (a hit) in, for example, one of the attribute, value, or source portion of the fact. Each hit is scored based on the frequency of the term that is hit, with more common terms getting lower scores, and rarer terms getting higher scores (e.g., using a TF-IDF based term weighting model). The fact score is then adjusted based on additional factors. These factors include the appearance of consecutive query terms in a fact, the appearance of consecutive query terms in a fact in the order in which they appear in the query, the appearance of an exact match for the entire query, the appearance of the query terms in the name fact (or other designated fact, e.g., property or category), and the percentage of facts of the object containing at least one query term. Each fact's score is also adjusted by its associated confidence measure and by its importance measure. Since each fact is independently scored, the facts most relevant and important to any individual query can be determined, and selected. In one embodiment, a selected number (e.g., 5) of the top scoring facts is selected for display in response to a query.

[0060] A user interface for browsing the fact repository 115 is discussed in co-pending U.S. application Ser. No. ______, entitled “Browsable Fact Repository” of Betz and Hogue, which is herein incorporated by reference.

[0061] Referring now to FIGS. 3(a) and 3(b), there are shown various examples from a user interface for querying the fact repository 115 in accordance with one embodiment of the present invention. In FIG. 3(a) there is shown a simple landing or home page for initiating a query of the fact repository 115. The page 300 includes a search query field 302 and a search objects button 304. The user enters any number of query terms into the search field 302 as described below. The terms can be any terms whatsoever, as they may appear in any fact. The user selects the search objects button 304 to provide the query terms to the service engine 114.

[0062] FIG. 3(b) illustrates the search result page 400 of a search, here for the search query “Michael Jackson.” The results page 400 includes a list of ranked search results 402, each search result 402 comprising a name link 416 to an object, the anchor text of the link 416 being the name of the object (the name link 416 resolves to an object detail page, as further described below). The results 402 are ranked according to their relevance to the search query. Each search result 402 (which for the purpose of this discussion can also be referred to as an object) is displayed with a label 406 indicating the category of the object (e.g., country, company, person, car, etc.).

[0063] Next to each search result 402 is displayed one example of an object search link 408. When selected, the object search link 408 causes a search query to be sent from the client device to the service engine. This search query is for objects of the same category as the search result object, and which contain the current search query terms in at least one of the facts associated with such object. For example, in response to the user clicking on the search link 406, a search query is sent to the service engine 127 for objects of category “country” and which contain the query term “china” in one or more facts. Thus, the object search link operates to further filter out the search results, such as the second and third search results 402 which are companies, and not countries.

[0064] Details of Query Language

[0065] As described above, queries to the repository 115 generally return objects. Which objects are returned is decided by search engine 123 in accordance with which facts match a query. For example, a query might be received from a web-based search engine such as that shown in FIGS. 3(a) and 3(b). A query could also be received in other ways, such as a payload in an http request sent to the service engine 114 and then passed to the search engine 123, and through an API of a service engine such as service engine 114.

[0066] Other embodiments return individual facts matching the query, instead of returning objects that contain matching facts.

[0067] FIG. 3(c) shows a flow chart 370 of a method performed by service engine 114 to process a search query. The search query first is received 372 and parsed 374. Then, service engine 114 loops for each term in the search query (376-380). For each term in the search query, the reverse index 127 is checked to determine which facts contain the query term. Service engine 114 determines 382 whether to return an object by determining whether its facts meet the requirements of the search query. The service engine 114 is also adapted to handle structured queries, using query operators that restrict the scope of a term match. For example, a fact restriction operator, comprising brackets enclosing terms, e.g., “[terms]”, restricts the term(s) to matching in a single fact. Field restriction operators attribute{ } and value{ } operators restrict to a single field.

[0068] A preferred embodiment of the present invention uses a query syntax as described below:

[0069] &|-( ): These are logical operators (respectively, AND, OR, NOT). If omitted, queries are assumed to have an implicit & operator. Parentheses are used to group terms and operators into logical groups. Note that the choice of characters used to indicate logical operators is merely an implementation choice. Any character or combination of characters can signal an operator.

[0070] “ ”: Double quotes surrounding a sequence of query terms require that the terms match in that order in a single field. This is called a phrase match.

[0071] ˆ: If a caret immediately precedes a word, it may only match the first word of a field and if the caret immediately follow a word, it may match only the last word of a field. Quotes and carets can be combined to produce an exact field match, for example “ˆGeorge W. Bushˆ”. In one embodiment, carets may only occur within quotes. In other embodiments, carets can applied to any term.

[0072] [ ]: Square brackets restrict the enclosed expression to appear in the same fact.

[0073] { } Curly brackets: restrict the enclosed expression to match a single field. This can be further restricted to a field of a specific type, such as attribute{ . . . } or value{ . . . }.

[0074] [X:Y]: Shortcut for [attribute{X} value{Y}]. Matches an attribute/value pair of a fact with the specified values.

[0075] FIG. 4 shows an example object 450 having ID#1 in fact repository 115. The object includes facts #1-4 (reference numbers 452, 454, 456, and 458). Fact #1 has an attribute of “Name” and a value of “John Smith.” Fact #2 has an attribute of “is-a” and a value of “person.” Fact #3 has an attribute of “Date of Birth” and a value of “6 Jul. 1946.” Fact #4 has an attribute of “Date of Death” and a value of “Aug. 12, 2005.” The following examples of query searches refer to the facts shown in FIG. 4.

[0076] The following paragraphs discuss examples of a query syntax that can be used to search repository 115. It will be understood that the Figures show examples of such a syntax and that other syntaxes could be used without departing from the spirit and scope of the present invention. Although the following examples show individual queries, it is also possible to refine a search with a further search, so that the initial search results are retained and searched again with additional queries that further refine the results. In one embodiment, the query terms are normalized before being applied. Such normalization might include removal of accents (diacritics), or stemming (removing of inflectional morphemes), or changing non-quoted terms to be all upper or all lower case.

[0077] FIG. 5(a) shows the following query that is entered into search query field 302:

[0078] Birth

[0079] This search query will return all objects whose facts contain the specified query term “Birth”. It is important to note that search queries performed by service engine 114 in accordance with the present invention look at both a fact's attribute (also called attribute name) and the fact's value (also called attribute value) to determine if the fact is relevant to the query. For example, the search query of FIG. 5(a) will match fact #3 because fact #3 has “Birth” in its “Date of Birth” attribute. The search query will return object #1 because object #1 is associated with fact #3.

[0080] Other embodiments of the present invention look at other portions of facts in addition to or instead of attributes and values. For example, other embodiments may default to also searching for query terms within a fact's links 216, metrics 218, sources, 220 or agents 222 and so on (see FIG. 2(d)). Still other embodiments may implement a query syntax that allows a user to explicitly search within various fields of a fact (such as links 216, metrics 218, sources 220, or agents 222 and so on). For example, in such an embodiment, the search query birth matches a fact containing a link field 216 of www.birth.com but would not match www.birthday.com. In other embodiments, a query of birth would match www.birthday.com since “birth” is contained in “birthday.”.

[0081] FIG. 5(b) shows the following query that is entered into search query field 302:

[0082] Birth August

[0083] In the described embodiment, a logical AND operator is implicit if no logical operator is specified for query terms. That is, an object must have associated facts matching both terms in order to be returned as a result of the query. This query will return all objects that have the term “Birth” and the term “August” in one or more of their facts. It is important to note that search queries performed in accordance with the present invention look at both a fact's attribute (also called attribute name) and the fact's value (also called attribute value) to determine if the fact is relevant to the query. For example, this search query will match fact #3 because fact #3 contains the term “Birth” (as an attribute). It will also match fact #4 because fact #4 contains “August” (as a value). Thus, this search query returns object #1 because object #1 is associated with matching facts #3 and #4.

[0084] FIG. 5(c) shows the following search query that is entered into search query field 302:

[0085] John &iIs-a

[0086] The ampersand (&) is an explicit logical operator that indicates that all search query terms must be present (although not necessarily in the same fact or in any particular field of the facts) for an object to match. This search query will return all objects with facts that contain both the term John” and the term “is-a”. Here, the term “John” is in fact #1 and the term “is-a” is an attribute of fact #2, so object #1 would be returned since it is associated with facts containing both search query terms.

[0087] Thus, even though the original source documents on document hosts 102 that were used to create the facts of object #1 may not have contained the word “is-a,” object #1 will be returned by the search query since at some point a fact with an attribute of is-a was added to the object. For example, a janitor whose function is categorizing objects might have created multiple new “is-a” facts having an attribute of “is-a” Thus, for example, a janitor 110 may exist that searches the fact repository 115 and categorizes objects, an creating new facts with an “is-a” attribute having a value of “person” “cat,”“dog” and so on for each categorized object. It will be possible for a user to enter a search query to locate all objects that have been categorized by the janitor (by searching for the attribute “is-a”). It would also be possible for a user to enter a search query to locate all objects that have been categorized as persons (by searching for the attribute “is-a” and the value “person” as an attribute/value pair within a single fact, as discussed below).

[0088] FIG. 5(d) shows the following search query that is entered into search query field 302:

[0089] John|“human being”

[0090] The vertical bar (|) is an explicit logical operator that indicates that only one query term much be present to match, although both may be present and still match. This search query will return all objects containing either the term “John” or the phrase “human being.” Here, the term “John” is in fact #1. Even though the phrase “human being” is not found, object #1 would be returned since it is associated with fact #1, and therefore satisfies the Boolean disjunction. FIG. 5(e) shows the following search query that is entered into search query field 302:

John{person

[0091] This search query will return all objects containing either the term “John” or the term “person”. Here, the term “John” is in fact #1 and the term “person” is an attribute of fact #2, so object #1 would be returned. Other embodiments may allow a user to perform an exclusive OR'd search (i.e., only one fact, not more or fewer must match).

[0092] FIG. 5(f) shows the following search query that is entered into search query field 302:

[0093] [Birth August]

[0094] A search query using square brackets ([ ]) will return all objects where both query terms are in the same fact. Here, this search query will return nothing since no object in the example has a fact containing both “Birth” and “August.” This is in contrast to the query Birth August of FIG. 5(b), which matched facts #3 and #4 and returned object #1. In one embodiment, logical operators can occur within square brackets. For example a query might contain: [(Birth August)|Birth]

[0095] In contrast, FIG. 5(g) shows the following search query that is entered into search query field 302:

[0096] [Birth Date]

[0097] This search query will return all objects where both query terms are in the same fact. The terms do not have to be an attribute/value pair in the fact. Here, this search query matches fact #3 since it has both terms (in its attribute name). Thus, this search query will return object #1 because it is associated with fact #3.

[0098] FIG. 5(h) shows the following search query that is entered into search query field 302:

[0099] [Birth:Date]

[0100] This search query will return all objects where the term on the left side of the “:” is an attribute name of a fact and the term on the right side of the “:” is an attribute value in the same fact. Here, there is no fact with an attribute containing the term “Birth” that also has a value containing the term “Date” so this search query does not match any facts in the example and no objects are returned. “In one embodiment, the right hand side and/or left hand side of the colon do not have to be exact matches unless the “A” operator is used.

[0101] In contrast, if the following search query of FIG. 5(i) was entered into search query field 302:

[0102] [Date:July]

[0103] This search query matches object #3 because object #3 includes a fact with an attribute containing the term “Date” and a value in the same fact containing the term “July”. Thus, object #1, which is associated with fact#3 would be returned. Note that the syntax with an attribute on the left and a value on the right with a colon between can use complex syntax, such as that specified below, on the right or the left side.

[0104] FIG. 5(j) shows the following search query that is entered into search query field 302:

[0105] {John Smith}

[0106] The matched pair of braces indicates that the terms within must match exactly in a single field. This search query will return all objects containing facts with the exact terms “John Smith”. For example, this search query will match fact #1 and thus return object #1.

[0107] FIG. 5(k) shows the following search query that is entered into search query field 302:

[0108] John W? Smith

[0109] The question mark “?” indicates that the term preceding it is optional. Thus, this search query will return all objects having a fact containing “John Smith” or “John W Smith”. In the example, it will match fact #1 and will return object #1.

[0110] FIG. 5(l) shows the following search query that is entered into search query field 302:

[0111] “ˆDate”

[0112] The caret “ˆ” before a term indicates that the term must occur at the beginning of a field. Thus, this search query will return all objects having a fact containing the term “Date” at the beginning of a field (e.g., at the beginning of an attribute or a value). In the example, it will match facts #3 and #4 and will return object #1. Some embodiments allow the caret to occur only in a quoted string. Other embodiments allow the caret to be used without quotes.

[0113] FIG. 5(m) shows the following search query that is entered into search query field 302:

[0114] “Dateˆ”

[0115] The caret “ˆ” after a term indicates that the term must occur at the end of a field. Thus, this search query will return all objects having a fact containing the term “Date” at the end of a field (e.g., at the end of an attribute or a value). In the example, it will not match any facts and will return no objects.

[0116] FIG. 5(n) shows the following search query that is entered into search query field 302:

[0117] “ˆDateˆ”

[0118] The caret “ˆ” before and after a term indicates that this query would match any field that consists of only the term “date”. Thus, this search query will return all objects having a fact containing the term “Date” (e.g., in an attribute or a value). With no characters preceding of following “date”. In the example, the search query will not match any facts and will return no objects. If, for example, a fact contained an attribute of the term “date” then that fact would match and its associated object would be returned.

[0119] FIG. 5(o) shows the following search query that is entered into search query field 302:

[0120] Attribute{Date} Value{August}

[0121] This search query allows the user to specify that the character string “Date” must be in an attribute and the character string “August” must be in a value. In the example, the search query will match facts #3 and #4 and will return object #1. The following paragraphs provide examples to illustrate the logical not operator (minus), which has complex interactions with the scoping operators [ ] and { }.

[0122] FIG. 5(p) shows a query:

[0123] George-W Bush

[0124] This query matches an object that contains one or more facts with “George” and one or more facts with “Bush”, but no facts with “W”.

[0125] FIG. 5(q) shows a query:

[0126] [George-W Bush]

[0127] This query matches any object with a fact that contains “George” and “Bush”, but not “W”.

[0128] FIG. 5(r) shows a query:

[0129] [George Bush]-[George W. Bush]

[0130] This query matches any object with a fact containing “George” and “Bush”, but not an object with a fact containing “George W. Bush”.

[0131] FIG. 5(s) shows a query:

[0132] [}George Bush}-{George W. Bush}]

[0133] This query matches an object with a fact that has a field containing “George Bush”, but no field containing “George W. Bush”.

[0134] FIG. 5(t) shows a query:

[0135] {George Bush-“George Bush”}

[0136] This query matches a field with the terms “george” and “bush”, but not in that order.

[0137] The above embodiment specified syntax requiring the query terms to be in the same fact. Other embodiments implement query syntax that requires the query terms to be in different facts. For example, in another embodiment, a search query containing angle brackets: <A B> might require that the terms “A” and “B” be present but be located in different facts. Other embodiments implement query syntax that requires one query term to be in an attribute and one query term to be in a value, but does not specify which is which.

[0138] The query of FIG. 5(b) defaults to not requiring the terms to be located in the same fact and require explicitly specifying when the terms must be in the same fact. In contrast, other embodiments default to requiring the terms to be located in the same fact and include syntax to force the terms to be located in different facts. In such an embodiment, Birth August requires that the terms “Birth” and “August” default to a requirement that they must be in the same fact while the search query [Birth August] requires that the terms are not in the same fact. The meaning (semantics) of the syntax in this example is exactly the opposite of the meaning of the syntax of FIGS. 5(a) and 5(f) and is presented herein to emphasize that the exact syntax used to send queries may differ in different embodiments of the present invention.

[0139] The present invention has been described in particular detail with respect to one possible embodiment. Those of skill in the art will appreciate that the invention may be practiced in other embodiments. First, the particular naming of the components, capitalization of terms, the attributes, data structures, or any other programming or structural aspect is not mandatory or significant, and the mechanisms that implement the invention or its features may have different names, formats, or protocols. Further, the system may be implemented via a combination of hardware and software, as described, or entirely in hardware elements. Also, the particular division of functionality between the various system components described herein is merely exemplary, and not mandatory; functions performed by a single system component may instead be performed by multiple components, and functions performed by multiple components may instead performed by a single component.

[0140] Some portions of above description present the features of the present invention in terms of algorithms and symbolic representations of operations on information. These algorithmic descriptions and representations are the means used by those skilled in the data processing arts to most effectively convey the substance of their work to others skilled in the art. These operations, while described functionally or logically, are understood to be implemented by computer programs. Furthermore, it has also proven convenient at times to refer to these arrangements of operations as modules or by functional names, without loss of generality.

[0141] Unless specifically stated otherwise as apparent from the above discussion, it is appreciated that throughout the description, discussions utilizing terms such as “processing” or “computing” or “calculating” or “determining” or “displaying” or the like, refer to the action and processes of a computer system, or similar electronic computing device, that manipulates and transforms data represented as physical (electronic) quantities within the computer system memories or registers or other such information storage, transmission or display devices.

[0142] Certain aspects of the present invention include process steps and instructions described herein in the form of an algorithm. It should be noted that the process steps and instructions of the present invention could be embodied in software, firmware or hardware, and when embodied in software, could be downloaded to reside on and be operated from different platforms used by real time network operating systems.

[0143] The present invention also relates to an apparatus for performing the operations herein. This apparatus may be specially constructed for the required purposes, or it may comprise a general-purpose computer selectively activated or reconfigured by a computer program stored on a computer readable medium that can be accessed by the computer. Such a computer program may be stored in a computer readable storage medium, such as, but is not limited to, any type of disk including floppy disks, optical disks, CD-ROMs, magnetic-optical disks, read-only memories (ROMs), random access memories (RAMs), EPROMs, EEPROMs, magnetic or optical cards, application specific integrated circuits (ASICs), or any type of media suitable for storing electronic instructions, and each coupled to a computer system bus. Furthermore, the computers referred to in the specification may include a single processor or may be architectures employing multiple processor designs for increased computing capability.

[0144] The algorithms and operations presented herein are not inherently related to any particular computer or other apparatus. Various general-purpose systems may also be used with programs in accordance with the teachings herein, or it may prove convenient to construct more specialized apparatus to perform the required method steps. The required structure for a variety of these systems will be apparent to those of skill in the, along with equivalent variations. In addition, the present invention is not described with reference to any particular programming language. It is appreciated that a variety of programming languages may be used to implement the teachings of the present invention as described herein, and any references to specific languages are provided for disclosure of enablement and best mode of the present invention.

[0145] The present invention is well suited to a wide variety of computer network systems over numerous topologies. Within this field, the configuration and management of large networks comprise storage devices and computers that are communicatively coupled to dissimilar computers and storage devices over a network, such as the Internet.

[0146] Finally, it should be noted that the language used in the specification has been principally selected for readability and instructional purposes, and may not have been selected to delineate or circumscribe the inventive subject matter. Accordingly, the disclosure of the present invention is intended to be illustrative, but not limiting, of the scope of the invention, which is set forth in the following claims.