YES TRS: a__f(f(a())) -> c(f(g(f(a())))) mark(f(X)) -> a__f(mark(X)) mark(a()) -> a() mark(c(X)) -> c(X) mark(g(X)) -> g(mark(X)) a__f(X) -> f(X) linear polynomial interpretations on N: a__f_A(x1) = 1 a__f#_A(x1) = 2 f_A(x1) = 1 f#_A(x1) = 0 a_A = 1 a#_A = 1 c_A(x1) = 1 c#_A(x1) = 0 g_A(x1) = 1 g#_A(x1) = 1 mark_A(x1) = 1 mark#_A(x1) = 3 precedence: a__f > mark > a = c = g > f