Principles and Practice of Constraint Programming — CP 2001

Volume 2239 of the series Lecture Notes in Computer Science pp 377-391


Sweep as a Generic Pruning Technique Applied to the Non-overlapping Rectangles Constraint

  • Nicolas BeldiceanuAffiliated withSICS
  • , Mats CarlssonAffiliated withSICS

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We first presen ta generic pruning technique which aggregates several constraints sharing some variables. The method is derived from an idea called sweep which is extensively used in computational geometry. A first benefit of this technique comes from the fact that it can be applied to several families of global constraints. A second advantage is that it does not lead to any memory consumption problem since it only requires temporary memory which can be reclaimed after each invocation of the method.

We then specialize this technique to the non-overlapping rectangles constraint, describe several optimizations, and give an empirical evaluation based on six sets of test instances with different characteristics.