Hi all, FYI new free software for knapsack problem ( http://en.wikipedia.org/wiki/Knapsack_problem ) has been made (written in Python language); it can solve possibly constrained, possibly (with interalg ) nonlinear and multiobjective problems with specifiable accuracy. Along with interalg lots of  MILP   solvers can be used. See http://openopt.org/KSP for details. Regards, Dmitrey.