JACK: A Java Constraint Kit Slim Abdennadher, Ekkerhard Krämer, Matthias Saft, Matthias Schmauss Most existing libraries providing constraint facilities are embedded in the logic programming language, Prolog, or in the object-oriented language, C++. Recently, some proposals have been made to integrate constraint handling in Java. The goal of this work is to provide a new constraint library for Java, called JACK. It consists of a high-level language for writing constraint solvers, a generic search engine and a tool to visualize the simplification and propagation of constraints.