Likelog for flexible query answering

 Starting from unification based on similarity, a logic programming language, called LIKEness in LOGic (Likelog) is derived, thorougly relying on similarity. An operational semantics and a fix-point semantics of the language are defined, using an extension principle for fuzzy operators. The two approaches are proved to be related and a fuzzy extension of the least Herbrand model is given. One of the principal feature of such a logic programming language is to allow flexible query answering to deductive databases, which we show through an example. Moreover, we describe a system for web information retrieval through Likelog.