YES O(n^2) TRS: { g(x, s(y)) -> g(f(x, y), 0()), g(0(), f(x, x)) -> x, g(f(x, y), 0()) -> f(g(x, 0()), g(y, 0())), g(s(x), y) -> g(f(x, y), 0()) } DUP: We consider a non-duplicating system. Trs: { g(x, s(y)) -> g(f(x, y), 0()), g(0(), f(x, x)) -> x, g(f(x, y), 0()) -> f(g(x, 0()), g(y, 0())), g(s(x), y) -> g(f(x, y), 0()) } Matrix Interpretation: Interpretation class: triangular [X1] [1 0][X1] [1] [s]([X0]) = [0 1][X0] + [1] [X3] [X1] [1 0][X3] [1 0][X1] [0] [f]([X2], [X0]) = [0 1][X2] + [0 1][X0] + [1] [0] [0] = [0] [X3] [X1] [1 1][X3] [1 1][X1] [0] [g]([X2], [X0]) = [0 1][X2] + [0 1][X0] + [0] Qed