Patent ID: 7725486

Claim:
An information retrieval apparatus for retrieving information, stored in a database, based on a search request, said information retrieval apparatus comprising: a general association dictionary storage unit that stores information identifying a relationship between words included in the information stored in the database; a preference-based association dictionary storage unit that stores information identifying a relationship, between the words included in the information stored in the database, which reflects a user's preferences regarding the information stored in the database, the information identifying the relationship that is stored in said preference-based association dictionary storage unit being independent from the information identifying the relationship that is stored in said general association dictionary storage unit; a matching degree calculation unit that extracts, based on (i) preference-based association dictionary characteristic information indicating a characteristic of a word stored in said preference-based association dictionary storage unit, (ii) status information indicating the user's status and (iii) emotion information expressing an emotion of the user, a word from information input by the user that matches or is similar to one of the preference-based association dictionary characteristic information, the status information, and the emotion information, and that calculates, as a degree of matching, a value calculated based on a weigh value of the extracted word; a search condition generation unit that: selects said general association dictionary storage unit when the degree of matching is equal to or smaller than a predetermined threshold value, and selects said preference-based association dictionary storage unit when the degree of matching is greater than the predetermined threshold value; obtains, as one or more related words, and depending on a number indicated by the value calculated as the degree of matching, one or more words that relate to the information input by the user, the one or more related words being obtained from one of said general association dictionary storage unit and said preference-based association dictionary storage unit that is selected by said search condition generation unit; and generates a search condition using the obtained one or more related words; and a retrieval unit that retrieves, from the database, information which meets the search condition generated by said search condition generation unit.