Multi Level Variable Ordering Heuristics for the Constraint Satisfaction Problem

The usual way for solving constraint satisfaction problems is to use a backtracking algorithm One of the key factors in its e ciency is the rule it will use to decide on which variable to branch next namely the variable ordering heuristics In this paper we attempt to give a general formulation of dynamic variable ordering heuristics that take into account the properties of the neighborhood of the variable An empirical evaluation on random CSPs and a sample of real instances shows that the obtained heuristics can improve signi cantly the current best ones