Explanations and error diagnosis

The report proposes a theoretical approach of the debugging of constraint programs based on the notion of explanation tree (D1.1.1 and D1.1.2 part 2). The proposed approach is an attempt to adapt algorithmic debugging to constraint programming. In this theoretical framework for domain reduction, explanations are proof trees explaining value removals. These proof trees are defined by inductive definitions which express the removals of values as consequence of other value removals. Explanations may be considered as the essence of constraint programming. They are a declarative view of the computation trace. The diagnosis consists in locating an error in an explanation rooted by a symptom. keywords: declarative diagnosis, algorithmic debugging, CSP, local consistency operator, fix-point, closure, inductive definition