refactoring solver_cese.py: abandon variable ga, use GAMMA
refactoring solver_cese.py: abandon variable ga, use GAMMA

solvcon/solvcon,solvcon/solvcon,yungyuc/solvcon,solvcon/solvcon,yungyuc/solvcon,yungyuc/solvcon,yungyuc/solvcon,yungyuc/solvcon,solvcon/solvcon,solvcon/solvcon,yungyuc/solvcon,solvcon/solvcon