Introduction

Maria I. Sessa has extended the SLD resolution principle with the ability of performing approximate reasoning [6]. Similarity-based SLD resolution (also known as weak SLD resolution) can be seen as an extension of the classical SLD resolution procedure where the syntactic unification algorithm has been replaced by a fuzzy unification algorithm based on a similarity relation.

Bousi$\sim$Prolog implements a fuzzy logic programming language that follows this inference scheme. The main goal is the implementation of a declarative programming language well suited for flexible query answering.