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