YES O(n^3) TRS: {f(f(x)) -> f(x), f(1()) -> f(g(1())), g(g(x)) -> g(x), g(0()) -> g(f(0()))} DUP: We consider a non-duplicating system. Trs: {f(f(x)) -> f(x), f(1()) -> f(g(1())), g(g(x)) -> g(x), g(0()) -> g(f(0())) } Matrix Interpretation: Interpretation class: triangular [0] [0] = [0] [1] [0] [1] = [1] [0] [X2] [1 0 1][X2] [0] [g]([X1]) = [0 0 0][X1] + [0] [X0] [0 0 0][X0] [1] [X2] [1 1 0][X2] [0] [f]([X1]) = [0 0 0][X1] + [1] [X0] [0 0 0][X0] [0] Qed