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