Section: New Results

Explanations for Contraint Programming (solver)

Participants : Narendra Jussien, Charles Prud'homme.

Constraint programming, despite its numerous successes in practice, suffers from not being really user-friendly when used by software engineers. Indeed, when faced with a no solution message from a constraint solver, it is hard yet impossible to identify the cause of this message: is it from a bad modelling, an ill-written constraint, a bug in the solver, .... Explanations for constraint programming have addressed this issue but are not yet widely used in the CP community. Recent work in the field tend to demonstrate that providing explanation-based user-oriented features can be done quite easily in modern constraint solvers. The objective of this line of work is to specify an user-oriented explanation-module for flexible solver architectures. This line of work is financed through a Google focused research grant . First results provide a complete solver independent specification of explanation algorithms, data structure for encoding nogoods and treatment algorithms. A reference implementation is being made within the new version of our solver CHOCO .