In this paper, we present RefGen, the main module of a topic detection system used to improve a search engine by topic indexing. RefGen identifies reference chains and it uses genre specific properties of reference chains and (Ariel 1990)’s accessibility theory. RefGen checks several strong and weak constraints (lexical, morphosyntactic and semantic filters) to automatically identify coreference relations between referential expressions. We present the first results obtained by RefGen from a public reports corpus.