Q: I am using GAMS to solve an LP decomposition algorithm and wondering how GAMS deals with the alternative optimal solutions
The optimal solution returned depends on the solver called, and sometimes on the options used (e.g. primal or dual simplex). GAMS will only receive one solution from the solver and report that one solution. Certain solvers also allow to report several solutions (e.g. BARON or CPLEX), for details please consult the solver manuals.