Temporal Document Retrieval Model for business news archives

Temporal expressions occurring in business news, such as “last week” or “at the end of this month,” carry important information about the time context of the news document and were proved to be useful for document retrieval. We found that about 10% of these expressions are difficult to project onto the calendar due to the uncertainty about their bounds. This paper introduces a novel approach to representing temporal expressions. A user study is conducted to measure the degree of uncertainty for selected temporal expressions and a method for representing uncertainty based on fuzzy numbers is proposed. The classical Vector Space Model is extended to the Temporal Document Retrieval Model (TDRM) that incorporates the proposed fuzzy representations of temporal expressions.