YES Problem: strict: s(a(x)) -> s(b(x)) b(b(x)) -> a(x) weak: f(s(x),y) -> f(x,s(y)) s(a(x)) -> a(s(x)) s(b(x)) -> b(s(x)) a(s(x)) -> s(a(x)) b(s(x)) -> s(b(x)) Proof: Matrix Interpretation Processor: dim=2 interpretation: [s](x0) = x0, [2 2] [1 2] [0] [f](x0, x1) = [0 0]x0 + [2 0]x1 + [2], [1 0] [1] [a](x0) = [0 0]x0 + [0], [1 0] [1] [b](x0) = [0 0]x0 + [0] orientation: [1 0] [1] [1 0] [1] s(a(x)) = [0 0]x + [0] >= [0 0]x + [0] = s(b(x)) [1 0] [2] [1 0] [1] b(b(x)) = [0 0]x + [0] >= [0 0]x + [0] = a(x) [2 2] [1 2] [0] [2 2] [1 2] [0] f(s(x),y) = [0 0]x + [2 0]y + [2] >= [0 0]x + [2 0]y + [2] = f(x,s(y)) [1 0] [1] [1 0] [1] s(a(x)) = [0 0]x + [0] >= [0 0]x + [0] = a(s(x)) [1 0] [1] [1 0] [1] s(b(x)) = [0 0]x + [0] >= [0 0]x + [0] = b(s(x)) [1 0] [1] [1 0] [1] a(s(x)) = [0 0]x + [0] >= [0 0]x + [0] = s(a(x)) [1 0] [1] [1 0] [1] b(s(x)) = [0 0]x + [0] >= [0 0]x + [0] = s(b(x)) problem: strict: s(a(x)) -> s(b(x)) weak: f(s(x),y) -> f(x,s(y)) s(a(x)) -> a(s(x)) s(b(x)) -> b(s(x)) a(s(x)) -> s(a(x)) b(s(x)) -> s(b(x)) Matrix Interpretation Processor: dim=5 interpretation: [1 0 0 0 0] [0 0 0 0 0] [s](x0) = [0 0 1 0 0]x0 [0 0 0 0 0] [0 0 0 0 0] , [1 0 0 0 0] [1 1 0 1 0] [1] [0 0 0 0 0] [0 0 1 0 0] [0] [f](x0, x1) = [0 0 1 0 0]x0 + [0 0 0 0 1]x1 + [0] [0 0 0 0 0] [0 0 0 0 0] [0] [0 0 0 0 0] [0 0 1 1 0] [0], [1 0 0 0 0] [1] [0 0 0 0 0] [0] [a](x0) = [0 0 0 0 0]x0 + [0] [0 0 0 0 0] [0] [0 0 0 0 0] [0], [1 0 0 0 0] [0 0 0 0 0] [b](x0) = [0 0 0 0 0]x0 [0 0 0 0 0] [0 0 0 0 0] orientation: [1 0 0 0 0] [1] [1 0 0 0 0] [0 0 0 0 0] [0] [0 0 0 0 0] s(a(x)) = [0 0 0 0 0]x + [0] >= [0 0 0 0 0]x = s(b(x)) [0 0 0 0 0] [0] [0 0 0 0 0] [0 0 0 0 0] [0] [0 0 0 0 0] [1 0 0 0 0] [1 1 0 1 0] [1] [1 0 0 0 0] [1 0 0 0 0] [1] [0 0 0 0 0] [0 0 1 0 0] [0] [0 0 0 0 0] [0 0 1 0 0] [0] f(s(x),y) = [0 0 1 0 0]x + [0 0 0 0 1]y + [0] >= [0 0 1 0 0]x + [0 0 0 0 0]y + [0] = f(x,s(y)) [0 0 0 0 0] [0 0 0 0 0] [0] [0 0 0 0 0] [0 0 0 0 0] [0] [0 0 0 0 0] [0 0 1 1 0] [0] [0 0 0 0 0] [0 0 1 0 0] [0] [1 0 0 0 0] [1] [1 0 0 0 0] [1] [0 0 0 0 0] [0] [0 0 0 0 0] [0] s(a(x)) = [0 0 0 0 0]x + [0] >= [0 0 0 0 0]x + [0] = a(s(x)) [0 0 0 0 0] [0] [0 0 0 0 0] [0] [0 0 0 0 0] [0] [0 0 0 0 0] [0] [1 0 0 0 0] [1 0 0 0 0] [0 0 0 0 0] [0 0 0 0 0] s(b(x)) = [0 0 0 0 0]x >= [0 0 0 0 0]x = b(s(x)) [0 0 0 0 0] [0 0 0 0 0] [0 0 0 0 0] [0 0 0 0 0] [1 0 0 0 0] [1] [1 0 0 0 0] [1] [0 0 0 0 0] [0] [0 0 0 0 0] [0] a(s(x)) = [0 0 0 0 0]x + [0] >= [0 0 0 0 0]x + [0] = s(a(x)) [0 0 0 0 0] [0] [0 0 0 0 0] [0] [0 0 0 0 0] [0] [0 0 0 0 0] [0] [1 0 0 0 0] [1 0 0 0 0] [0 0 0 0 0] [0 0 0 0 0] b(s(x)) = [0 0 0 0 0]x >= [0 0 0 0 0]x = s(b(x)) [0 0 0 0 0] [0 0 0 0 0] [0 0 0 0 0] [0 0 0 0 0] problem: strict: weak: f(s(x),y) -> f(x,s(y)) s(a(x)) -> a(s(x)) s(b(x)) -> b(s(x)) a(s(x)) -> s(a(x)) b(s(x)) -> s(b(x)) Qed