> Someone can point me how to model the "or" conditions? >
See the example model examples/jssp.mod included in the glpk distribution that illustrates modeling disjunctive conditions. Note that your 2d cutting stock problem can be modeled as mip at least in two different ways: i) the unknowns are x and y coordinates of each rectangle which are continuous variables, where the disjunctive conditions are modeled with auxiliary binary variables; ii) the unknowns are binary variables x[i,j,k], where x[i,j,k] = 1 means that rectangle k covers a rectangular cell (i,j) assuming that the entire paper is divided into a set of the cells. The model jssp.mod corresponds to the case (i). However, the case (ii) has many advantages, in particular, it allows to reduce your problem to the satisfiability problem (that can be efficiently solved with the Minisat solver included in glpk). _______________________________________________ Help-glpk mailing list [email protected] https://lists.gnu.org/mailman/listinfo/help-glpk
