M. García de la Banda

On implementing symmetry detection

Automatic symmetry detection has received a significant amount of interest, which has resulted in a large number of proposed methods. This paper reports on our experiences while implementing the approach of Puget (CP2005, LNCS, vol. 3709, pp. 475–489. Springer, 2005). In particular, it proposes a modification to the approach to deal with general expressions, discusses the insights gained, and gives the results of an experimental evaluation of the accuracy and efficiency of the approach.

ViMer: a visual debugger for mercury

ViMer is a visual debugging environment for Mercury programs which has three main contributions. First, it employs a new execution tree representation, the layered AND-OR tree, which we believe provides a better way of visualizing backtracking in AND-OR-like trees. Second, it uses incremental constraint-solving to efficiently draw and incrementally update the visualization of the execution tree. And finally, it borrows techniques from standard tracers (such as the use of spy points to reduce the amount of tree nodes, and the placement of restrictions on the amount of information stored at each node) that help keep the tool efficient while still providing enough information for debugging.

A novel approach for detecting symmetries in CSP models

While several powerful methods exist for automatically detecting symmetries in instances of constraint satisfaction problems (CSPs), current methods for detecting symmetries in CSP models are limited to the kind of symmetries that can be inferred from the global constraints present in the model. Herein, a new approach for detecting symmetries in CSP models is presented. The approach is based on first applying powerful methods to a sequence of problem instances, and then reasoning on the resulting instance symmetries to infer symmetries of the model. Our results show that this approach deserves further exploration.