YES Problem: f(a,empty()) -> g(a,empty()) f(a,cons(x,k)) -> f(cons(x,a),k) g(empty(),d) -> d g(cons(x,k),d) -> g(k,cons(x,d)) Proof: Matrix Interpretation Processor: dim=1 interpretation: [cons](x0, x1) = x0 + x1 + 2, [g](x0, x1) = x0 + x1, [f](x0, x1) = x0 + x1, [empty] = 5 orientation: f(a,empty()) = a + 5 >= a + 5 = g(a,empty()) f(a,cons(x,k)) = a + k + x + 2 >= a + k + x + 2 = f(cons(x,a),k) g(empty(),d) = d + 5 >= d = d g(cons(x,k),d) = d + k + x + 2 >= d + k + x + 2 = g(k,cons(x,d)) problem: f(a,empty()) -> g(a,empty()) f(a,cons(x,k)) -> f(cons(x,a),k) g(cons(x,k),d) -> g(k,cons(x,d)) Matrix Interpretation Processor: dim=1 interpretation: [cons](x0, x1) = x0 + x1 + 1, [g](x0, x1) = 3x0 + 2x1 + 4, [f](x0, x1) = 3x0 + 3x1 + 3, [empty] = 1 orientation: f(a,empty()) = 3a + 6 >= 3a + 6 = g(a,empty()) f(a,cons(x,k)) = 3a + 3k + 3x + 6 >= 3a + 3k + 3x + 6 = f(cons(x,a),k) g(cons(x,k),d) = 2d + 3k + 3x + 7 >= 2d + 3k + 2x + 6 = g(k,cons(x,d)) problem: f(a,empty()) -> g(a,empty()) f(a,cons(x,k)) -> f(cons(x,a),k) Matrix Interpretation Processor: dim=3 interpretation: [1 0 0] [1 0 0] [0] [cons](x0, x1) = [0 0 0]x0 + [0 0 0]x1 + [0] [0 0 0] [0 0 1] [1], [1 0 0] [1 0 0] [g](x0, x1) = [0 0 0]x0 + [0 0 0]x1 [0 0 0] [0 0 0] , [1 0 0] [1 0 1] [f](x0, x1) = [0 0 0]x0 + [0 0 0]x1 [0 0 0] [0 0 0] , [0] [empty] = [0] [1] orientation: [1 0 0] [1] [1 0 0] f(a,empty()) = [0 0 0]a + [0] >= [0 0 0]a = g(a,empty()) [0 0 0] [0] [0 0 0] [1 0 0] [1 0 1] [1 0 0] [1] [1 0 0] [1 0 1] [1 0 0] f(a,cons(x,k)) = [0 0 0]a + [0 0 0]k + [0 0 0]x + [0] >= [0 0 0]a + [0 0 0]k + [0 0 0]x = f(cons(x,a),k) [0 0 0] [0 0 0] [0 0 0] [0] [0 0 0] [0 0 0] [0 0 0] problem: Qed