YES O(n^4) TRS: {f(g(X)) -> f(X)} DUP: We consider a non-duplicating system. Trs: {f(g(X)) -> f(X)} Matrix Interpretation: Interpretation class: triangular [X3] [1 0 0 0][X3] [0] [X2] [0 1 0 0][X2] [1] [g]([X1]) = [0 0 0 0][X1] + [0] [X0] [0 0 0 0][X0] [0] [X3] [1 1 0 0][X3] [0] [X2] [0 0 0 0][X2] [0] [f]([X1]) = [0 0 0 0][X1] + [0] [X0] [0 0 0 0][X0] [0] Qed