YES O(n^3) TRS: { a__f(X) -> f(X), a__f(0()) -> cons(0(), f(s(0()))), a__f(s(0())) -> a__f(a__p(s(0()))), a__p(X) -> p(X), a__p(s(0())) -> 0(), mark(cons(X1, X2)) -> cons(mark(X1), X2), mark(0()) -> 0(), mark(f(X)) -> a__f(mark(X)), mark(s(X)) -> s(mark(X)), mark(p(X)) -> a__p(mark(X)) } DUP: We consider a non-duplicating system. Trs: { a__f(X) -> f(X), a__f(0()) -> cons(0(), f(s(0()))), a__f(s(0())) -> a__f(a__p(s(0()))), a__p(X) -> p(X), a__p(s(0())) -> 0(), mark(cons(X1, X2)) -> cons(mark(X1), X2), mark(0()) -> 0(), mark(f(X)) -> a__f(mark(X)), mark(s(X)) -> s(mark(X)), mark(p(X)) -> a__p(mark(X)) } Matrix Interpretation: Interpretation class: triangular [X2] [1 0 0][X2] [0] [p]([X1]) = [0 1 1][X1] + [0] [X0] [0 0 0][X0] [3] [X2] [1 3 3][X2] [0] [mark]([X1]) = [0 1 0][X1] + [0] [X0] [0 0 1][X0] [0] [X2] [1 0 0][X2] [2] [a__p]([X1]) = [0 1 1][X1] + [0] [X0] [0 0 0][X0] [3] [X2] [1 0 3][X2] [3] [a__f]([X1]) = [0 1 3][X1] + [0] [X0] [0 0 0][X0] [2] [X2] [1 0 0][X2] [0] [s]([X1]) = [0 1 1][X1] + [0] [X0] [0 0 1][X0] [3] [X2] [1 0 0][X2] [0] [f]([X1]) = [0 1 3][X1] + [0] [X0] [0 0 0][X0] [2] [3] [0] = [3] [2] [X5] [X2] [1 0 2][X5] [1 0 0][X2] [1] [cons]([X4], [X1]) = [0 1 1][X4] + [0 0 0][X1] + [0] [X3] [X0] [0 0 0][X3] [0 0 0][X0] [1] Qed