YES O(n^2) TRS: { f(f(x)) -> f(x), f(s(x)) -> f(x), g(s(0())) -> g(f(s(0())))} DUP: We consider a non-duplicating system. Trs: { f(f(x)) -> f(x), f(s(x)) -> f(x), g(s(0())) -> g(f(s(0())))} Matrix Interpretation: Interpretation class: triangular [0] [0] = [1] [X1] [1 1][X1] [0] [g]([X0]) = [0 0][X0] + [0] [X1] [1 0][X1] [1] [s]([X0]) = [0 1][X0] + [1] [X1] [1 0][X1] [1] [f]([X0]) = [0 0][X0] + [0] Qed