YES O(n^3) TRS: {p(p(b(a(x0)), x1), p(x2, x3)) -> p(p(b(x2), a(a(b(x1)))), p(x3, x0))} DUP: We consider a non-duplicating system. Trs: {p(p(b(a(x0)), x1), p(x2, x3)) -> p(p(b(x2), a(a(b(x1)))), p(x3, x0))} Matrix Interpretation: Interpretation class: triangular [X2] [1 1 0][X2] [0] [a]([X1]) = [0 0 0][X1] + [0] [X0] [0 0 1][X0] [1] [X2] [1 0 0][X2] [0] [b]([X1]) = [0 0 0][X1] + [0] [X0] [0 0 1][X0] [0] [X5] [X2] [1 0 1][X5] [1 1 0][X2] [0] [p]([X4], [X1]) = [0 0 0][X4] + [0 0 1][X1] + [0] [X3] [X0] [0 0 0][X3] [0 0 0][X0] [0] Qed