Publication details

Saarland University Computer Science

Practical Investigation of Constraints with Graph Views

Tobias Müller

Proceedings of the International Workshop on Implementation of Declarative Languages (IDL'99), September 1999

Combinatorial problems can be efficiently tackled with constraint programming systems. The main tasks of the development of a constraint-based application are modeling the problem at hand and subsequently implementing that model. Typically, erroneous behavior of a constraint-based application is caused by either the model or the implementation (or both of them). Current constraint programming systems provide limited debugging support for modeling and implementing a problem.
This paper proposes the Constraint Investigator, an interactive tool for debugging the model and the implementation of a constraint-based application. In particular, the Investigator is targeted at problems like wrong, void, or partial solutions. A graph metaphor is used to reflect the constraints in the solver and to present them to the user. The paper shows that this metaphor is intuitive and that it scales up to real-life problem sizes.
The Constraint Investigator has been implemented in Mozart Oz. It complements other constraint debugging tools as an interactive search tree visualizer, forming the base for an integrated constraint debugging environment.

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