1. A computerized apparatus having a processor, the processor being adapted to perform the steps of: obtaining a set of solutions to a multi-objective problem, wherein each solution is a non-dominated solution; computing outranking weights for each pair of solutions; selecting a subset of the set of solutions based upon a defensive criteria in with respect to the outranking weights, wherein the defensive criteria relates to a number of solutions that outrank the subset; and outputting the subset of the set of solutions.