Data processing: database and file management or data structures – Database design – Data structure types
Reexamination Certificate
1998-03-10
2001-02-06
Alam, Hosain T. (Department: 2771)
Data processing: database and file management or data structures
Database design
Data structure types
C705S007380, C705S037000
Reexamination Certificate
active
06185558
ABSTRACT:
TECHNICAL FIELD
The present invention is directed to the field of query processing.
BACKGROUND OF THE INVENTION
Many World Wide Web sites permit users to perform searches to identify a small number of interesting items among a much larger domain of items. As an example, several web index sites permit users to search for particular web sites among most of the known web sites. Similarly, many online merchants, such as booksellers, permit users to search for particular products among all of the products that can be purchased from a merchant. In many cases, users perform searches in order to ultimately find a single item within an entire domain of items.
In order to perform a search, a user submits a query containing one or more query terms. The query also explicitly or implicitly identifies a domain of items to search. For example, a user may submit a query to an online bookseller containing terms that the user believes are words in the title of a book. A query server program processes the query to identify within the domain items matching the terms of the query. The items identified by the query server program are collectively known as a query result. In the example, the query result is a list of books whose titles contain some or all of the query terms. The query result is typically displayed to the user as a list of items. This list may be ordered in various ways. For example, the list may be ordered alphabetically or numerically based on a property of each item, such as the title, author, or release date of each book. As another example, the list may be ordered based on the extent to which each identified item matches the terms of the query.
When the domain for a query contains a large number of items, it is common for query results to contain tens or hundreds of items. Where the user is performing the search in order to find a single item, application of conventional approaches to ordering the query result often fail to place the sought item or items near the top of the query result, so that the user must read through many other items in the query result before reaching the sought item. In view of this disadvantage of conventional approaches to ordering query results, a new, more effective technique for automatically ordering query results in accordance with collective and individual user behavior would have significant utility.
Further, it is fairly common for users to specify queries that are not satisfied by any items. This may happen, for example, where a user submits a detailed query that is very narrow, or where a user mistypes or misremembers a term in the query. In such cases, conventional techniques, which present only items that satisfy the query, present no items to the user. When no items are presented to a user in response to issuing a query, the user can become frustrated with the search engine, and may even discontinue its use. Accordingly, a technique for displaying items relating to at least some of the terms in a query even when no items completely match the query would have significant utility.
In order to satisfy this need, some search engines adopt a strategy of effectively automatically revising the query until a non-empty result set is produced. For example, a search engine may progressively delete conjunctive, i.e., ANDed, terms from a multiple term query until the result set produced for that query contains items. This strategy has the disadvantage that important information for choosing the correct items can be lost when query terms are arbitrarily deleted. As a result, the first nonempty result set can be quite large, and may contain a large percentage of items that are irrelevant to the original query as a whole. For this reason, a more effective technique for displaying items relating to at least some of the terms in a query even when no items completely match the query would have significant utility.
SUMMARY OF THE INVENTION
The present invention provides a software facility (“the facility”) for identifying the items most relevant to a current query based on items selected in connection with similar queries. The facility preferably generates ranking values for items indicating their level of relevance to the current query, which specifies one or more query terms. The facility generates a ranking value for an item by combining rating scores, produced by a rating function, that each correspond to the level of relevance of the item to queries containing one of the ranking values. The rating function preferably retrieves a rating score for the combination of an item and a term from a rating table generated by the facility. The scores in the rating table preferably reflect, for a particular item and term, how often users have selected the item when the item has been identified in query results produced for queries containing particular term.
In different embodiments, the facility uses the rating scores to either generate a ranking value for each item in a query result, or generate ranking values for a smaller number of items in order to select a few items having the top ranking values. To generate a ranking value for a particular item in a query result, the facility combines the rating scores corresponding to that item and the terms of the query. In embodiments in which the goal is to generate ranking values for each item in the query result, the facility preferably loops through the items in the query results and, for each item, combines all of the rating scores corresponding to that item and any of the terms in the query. On the other hand, in embodiments in which the goal is to select a few items in the query result having the largest ranking values, the facility preferably loops through the terms in the query, and, for each item, identifies the top few rating scores for that term and any item. The facility then combines the scores identified for each item to generate ranking values for a relatively small number of items, which may include items not identified in the query result. Indeed, these embodiments of the invention are able to generate ranking values for and display items even in cases in which the query result is empty, i.e., when no items completely satisfy the query.
Once the facility has generated ranking values for at least some items, the facility preferably orders the items of the query result in decreasing order of ranking value. The facility may also use the ranking values to subset the items in the query result to a smaller number of items. By ordering and/or subsetting the items in the query result in this way in accordance with collective and individual user behavior rather than in accordance with attributes of the items, the facility substantially increases the likelihood that the user will quickly find within the query result the particular item or items that he or she seeks. For example, while a query result for a query containing the query terms “human” and “dynamic” may contain a book about human dynamics and a book about the effects on human beings of particle dynamics, selections by users from earlier query results produced for queries containing the term “human” show that these users select the human dynamics book much more frequently than they select the particle dynamics book. The facility therefore ranks the human dynamics book higher than the particle dynamics book, allowing users that are more interested in the human dynamics book to select it more easily. This benefit of the facility is especially useful in conjunction with the large, heterogeneous query results that are typically generated for single-term queries, which are commonly submitted by users.
Various embodiments of the invention base rating scores on different kinds of selection actions performed by the users on items identified in query results. These include whether the user displayed additional information about an item, how much time the user spent viewing the additional information about the item, how many hyperlinks the user followed within the additional information about the item, whether the user added the item to his or her shopping basket, a
Bowman Dwayne
Linden Greg
Ortega Ruben E.
Spiegel Joel R.
Alam Hosain T.
Amazon.Com, Inc.
Perkins Coie LLP
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