1. Introduction
Cross-language information retrieval (CLIR) is the circumstance in which a user tries to search a set of
documents written in one language for a query in another language. The issues of CLIR have been discussed
for several decades. As widely recognized, research efforts for developing CLIR techniques can be
traced back to Gerard Saltons articles in the early 1970s (e.g., Salton, 1970).
Especially after the advent of the World Wide Web in the 1990s, CLIR has become more important,
allowing users to access information resources written in a variety of languages on the Internet. Since then,
the research community of IR has begun to tackle problems of CLIR extensively and intensively. The
Workshop on Cross-Linguistic Information Retrieval held in August 1996 during the SIGIR96 Conference
is frequently cited as an epochal event for promoting research on CLIR.