The present invention relates generally to the field of computer-based information retrieval, and more specifically to a system and method for improving information retrieval effectiveness by dynamically combining evidence information produced by a plurality of retrieval systems matching alternative representations of queries and documents.
Computer-based information retrieval is now an established industry serving many professional communities. Retrieval technologies used in this industry share many common features. For example, a user of these systems is typically required to either (1) state an information need, or query, in a circumscribed manner, usually by denoting the logical requirements of the query as a sequence of terms linked by various operators, or (2) write the query as free-form text, which is then parsed automatically into a sequence of words or phrases, without regard for the logical form of the query or the underlying meaning of the query. In either event the query is represented only by the collection of words that are overtly stated in the query text (or limited stemmed forms of some words, such as plurals). The matching of documents to a query is based on the co-occurrence of these words or phrases.
A second commonality among retrieval systems is that a query representation derived from a user's query statement is automatically formed by the computer system, with limited or no interaction with the user. In most retrieval systems, once an initial query statement has been made in full, the computer system interprets the contents of the query without allowing the user to verify, clarify or expand upon query representations created by the computerized retrieval system. In the same fashion, the subsequent display of retrieved documents is largely under computer control, with little user interaction.
Further several techniques have been developed for retrieving desired items from a collection of several items to satisfy a user's information needs as expressed through the query. However, most of these retrieval techniques fail to provide a comprehensive solution to the information retrieval problem. Although each retrieval technique provides its own independent evidence to rate collection of retrieved items for their relevance to the user's query, no one approach has been successful in providing all the evidence. A common solution to overcome limitations of individual search techniques has been to combine the results of a plurality of search techniques into a single set of results. This is usually done using static or fixed combination functions such as adding the results of the different retrieval techniques. Although this may provide improvements over individual search techniques, it does not take into consideration that different queries may be best served using different combination rules.
In view of the above, there is a need for an information retrieval technique which increases the effectiveness and preciseness of information retrieval while combining the results of multiple retrieval approaches. Further, it is desirable that the information retrieval technique capture both the preciseness and richness of meaning in queries and documents and allow for user feedback to facilitate the retrieval process.