Symmetry Breaking in a Rack Configuration Problem

We address the issue of reducing symmetry in a rack configuration problem, which can be modelled as a constraint satisfaction problem. The problem has a large number of symmetries that are difficult to break. We propose considering different views of the problem, which leads to different models. Within these different models, we seek opportunities for reducing the symmetries. The best result was obtained by integrating a primal model of the problem with its corresponding dual model. Experimental results on the integrated model show an exponential decrease in terms of failures and runtime, compared to all the other models considered.