YES O(n^2) 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] [X3] [X1] [1 0][X3] [1 1][X1] [0] [+]([X2], [X0]) = [0 1][X2] + [0 1][X0] + [0] [X3] [X1] [1 1][X3] [1 0][X1] [0] [*]([X2], [X0]) = [0 1][X2] + [0 1][X0] + [1] Qed