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