YES O(n^4) TRS: { *(x, x) -> x, *(x, *(y, z)) -> *(*(x, y), z)} DUP: We consider a non-duplicating system. Trs: { *(x, x) -> x, *(x, *(y, z)) -> *(*(x, y), z)} Matrix Interpretation: Interpretation class: triangular [X7] [X3] [1 0 0 0][X7] [1 1 0 0][X3] [1] [X6] [X2] [0 1 0 0][X6] [0 0 0 1][X2] [1] [*]([X5], [X1]) = [0 0 0 0][X5] + [0 0 1 0][X1] + [0] [X4] [X0] [0 0 0 1][X4] [0 0 0 1][X0] [1] Qed