YES Problem: f(x,empty()) -> x f(empty(),cons(a,k)) -> f(cons(a,k),k) f(cons(a,k),y) -> f(y,k) Proof: Matrix Interpretation Processor: dim=1 interpretation: [cons](x0, x1) = x0 + 7x1 + 1, [f](x0, x1) = x0 + 4x1 + 1, [empty] = 4 orientation: f(x,empty()) = x + 17 >= x = x f(empty(),cons(a,k)) = 4a + 28k + 9 >= a + 11k + 2 = f(cons(a,k),k) f(cons(a,k),y) = a + 7k + 4y + 2 >= 4k + y + 1 = f(y,k) problem: Qed