YES TRS: active(f(X)) -> mark(g(h(f(X)))) mark(f(X)) -> active(f(mark(X))) mark(g(X)) -> active(g(X)) mark(h(X)) -> active(h(mark(X))) f(mark(X)) -> f(X) f(active(X)) -> f(X) g(mark(X)) -> g(X) g(active(X)) -> g(X) h(mark(X)) -> h(X) h(active(X)) -> h(X) linear polynomial interpretations on N: active_A(x1) = x1 active#_A(x1) = x1 + 1 f_A(x1) = x1 + 5 f#_A(x1) = x1 + 7 mark_A(x1) = x1 + 1 mark#_A(x1) = x1 + 4 g_A(x1) = 1 g#_A(x1) = x1 h_A(x1) = x1 h#_A(x1) = x1 precedence: f = mark > active > g = h