Symmetry breaking in mixed integer linear programming formulations for blocking two-level orthogonal experimental designs.

•Orthogonal blocking is a challenging problem in design of experiments.•The problem can be tackled using integer linear programming (ILP).•Symmetry breaking formulations speed up the solution of the ILP.•For some instances, an asymmetric representatives formulation is extremely fast.•Our work remains useful even though solvers implement symmetry breaking too.