YES O(n^3) TRS: { *(*(x, y), z) -> *(x, *(y, z)), +(*(x, y), *(a(), y)) -> *(+(x, a()), y) } DUP: We consider a non-duplicating system. Trs: { *(*(x, y), z) -> *(x, *(y, z)), +(*(x, y), *(a(), y)) -> *(+(x, a()), y) } Matrix Interpretation: Interpretation class: triangular [0] [a] = [0] [0] [X5] [X2] [1 0 0][X5] [1 0 0][X2] [0] [+]([X4], [X1]) = [0 0 0][X4] + [0 0 0][X1] + [0] [X3] [X0] [0 0 1][X3] [0 0 1][X0] [0] [X5] [X2] [1 0 1][X5] [1 0 0][X2] [1] [*]([X4], [X1]) = [0 0 0][X4] + [0 0 0][X1] + [0] [X3] [X0] [0 0 1][X3] [0 0 1][X0] [1] Qed