Patent ID: 8161032

Claim:
A thread ranking system comprising: an event knowledge storage that stores an event knowledge that is a feature expression to be used for extracting an event in which a user is interested from threads; a collecting unit that collects the threads from a bulletin board website on a communication network, each of the threads containing a plurality of articles including a title and a main body; a thread information storage that stores the threads collected by the collecting unit; an event extracting unit that extracts the event from respective threads stored in the thread information storage, by using the event knowledge stored in the event knowledge storage; a related expression extracting unit that extracts a related expression characterizing each of the threads from expressions contained in the threads, by referring to the threads stored in the thread information storage; a presentation unit that presents information to the user for allowing the user to input an evaluation of a predetermined thread stored in the thread information storage; an input unit that allows the user to input the evaluation of the predetermined thread; a related expression importance calculation unit that calculates importance based on the evaluation of the user input through the input unit for the respective related expressions; and a thread ranking unit that determines ranks of the respective threads stored in the thread information storage based on the event extracted by the event extracting unit and the importance calculated by the related expression importance calculation unit, wherein the event extracting unit operates to: apply a morphological analysis to the main body of each of the articles contained in the threads; and extract an event corresponding to the event knowledge when an expression indicated by the event knowledge stored in the event knowledge storage is contained in the main body of the article to which the morphological analysis is applied.