JHU/APL experiments at CLEF: Translation resources and score normalization

Abstract

The Johns Hopkins University Applied Physics Laboratory participated in three of the five tasks of the CLEF-2001 evaluation, monolingual retrieval, bilingual retrieval, and multilingual retrieval. In this paper we describe the fundamental methods we used and we present initial results from three experiments. The first investigation examines whether residual inverse document frequency can improve the term weighting methods used with a linguistically motivated probabilistic model. The second experiment attempts to assess the benefit of various translation resources for cross-language retrieval. Our last effort is to improve cross-collection score normalization, a task essential for the multilingual problem.