Time-dependent event hierarchy construction

In this paper, an algorithm called Time Driven Documents-partition (TDD) is proposed to construct an event hierarchy in a text corpus based on a given query. Specifically, assume that a query contains only one feature - Election. Election is directly related to the events such as 2006 US Midterm Elections Campaign, 2004 US Presidential Election Campaign and 2004 Taiwan Presidential Election Campaign, where these events may further be divided into several smaller events (e.g. the 2006 US Midterm Elections Campaign can be broken down into events such as campaign for vote, election results and the resignation of Donald H. Rumsfeld). As such, an event hierarchy is resulted. Our proposed algorithm, TDD, tackles the problem by three major steps: (1)Identify the features that are related to the query according to both the timestamps and the contents of the documents. The features identified are regarded as bursty features; (2) Extract the documents that are highly related to the bursty features based on time; (3) Partition the extracted documents to form events and organize them in a hierarchicalstructure. To the best of our knowledge, there is little works targeting for constructing a feature-based event hierarchy for a text corpus. Practically, event hierarchies can assist us to efficiently locate our target information in a text corpus easily. Again, assume that Election is used for a query. Without an event hierarchy, it is very difficult to identify what are the major events related to it, when do these events happened, as well as the features and the news articles that are related to each of these events. We have archived two-year news articles to evaluate the feasibility of TDD. The encouraging results indicated that TDD is practically sound and highly effective.