YES TRS: f(s(X),X) -> f(X,a(X)) f(X,c(X)) -> f(s(X),X) f(X,X) -> c(X) linear polynomial interpretations on N: f_A(x1,x2) = x1 + x2 + 1 f#_A(x1,x2) = x2 + 2 s_A(x1) = x1 + 1 s#_A(x1) = 0 a_A(x1) = x1 a#_A(x1) = 1 c_A(x1) = x1 + 1 c#_A(x1) = 1 precedence: f > a = c > s