Symmetry Breaking by Nonstationary Optimisation

We describe a new partial symmetry breaking method that can be used to break arbitrary variable/value symmetries in combination with depth first search, static value ordering and dynamic variable ordering. The main novelty of the method is a new dominance detection technique based on local search in the symmetry group. It has very low time and memory requirements, yet in preliminary experiments on BIBD design it breaks most symmetries and is competitive with several other methods.