I am working on a resource allocation problem using an SPEA 2 evolutionary algorithm. The problem involves a decision variable where each variable has a different domain e.g. Ei < di where Ei is the allocation to a user and di is individual demands. The problem involves a linear constraint such that sum(Ei) = total resource. The probability of the creation of feasible off-springs after crossover and mutation operators is extremely low. So, we need a repair operator for this purpose. I need guidance for the selection of suitable repair operators and how should I apply that, I mean should we repair all solutions or some percentage. I would appreciate the guidance, comments, or any literature reference.