YES O(n^2) TRS: {f(c(X, s(Y))) -> f(c(s(X), Y)), g(c(s(X), Y)) -> f(c(X, s(Y)))} DUP: We consider a non-duplicating system. Trs: {f(c(X, s(Y))) -> f(c(s(X), Y)), g(c(s(X), Y)) -> f(c(X, s(Y)))} Matrix Interpretation: Interpretation class: triangular [X1] [1 1][X1] [1] [g]([X0]) = [0 0][X0] + [0] [X1] [1 0][X1] [0] [s]([X0]) = [0 1][X0] + [1] [X3] [X1] [1 0][X3] [1 1][X1] [0] [c]([X2], [X0]) = [0 0][X2] + [0 0][X0] + [1] [X1] [1 0][X1] [0] [f]([X0]) = [0 0][X0] + [0] Qed