An Interactive Tool for the Controlled Execution of an Automated Timetabling Constraint Engine

Abstract

Here we introduce DePathos, a graphical tool for a time-tabling constraint engine (Pathos). Since the core of Pathos is text-based and provides little user-interaction, finding an appropriate solution for large problems (1000-2000 variables) can be a very time consuming process requiring the constant supervision of a constraint programming expert. DePathos uses an incremental solution strategy. Such strategy subdivides the problem and checks the consistency of the resulting subdivisions before incrementally unifying them. This has shown to be useful in finding inconsistencies and discovering over-constrained situations. Our incremental solution is based on hierarchical groupings defined at the problem domain level. This allows users to direct the timetabling engine in finding partial solutions that are meaningful in practice. We discuss the lessons learned from using Pathos in real settings, as well as the experiences of coupling DePathos to the timetabling engine.

This work was partially supported by the Colombian Institute for Science and Technology Development (Colciencias) under the CRISOL project (Contract No.298-2002).