YES Problem: strict: a(b(x1)) -> b(a(x1)) d(c(x1)) -> d(a(x1)) weak: a(x1) -> b(c(x1)) b(c(x1)) -> a(c(x1)) Proof: Matrix Interpretation Processor: dim=2 interpretation: [1 0] [a](x0) = [0 0]x0, [2 1] [0] [d](x0) = [0 1]x0 + [1], [1 0] [b](x0) = [0 0]x0, [1 0] [0] [c](x0) = [0 2]x0 + [2] orientation: [1 0] [1 0] a(b(x1)) = [0 0]x1 >= [0 0]x1 = b(a(x1)) [2 2] [2] [2 0] [0] d(c(x1)) = [0 2]x1 + [3] >= [0 0]x1 + [1] = d(a(x1)) [1 0] [1 0] a(x1) = [0 0]x1 >= [0 0]x1 = b(c(x1)) [1 0] [1 0] b(c(x1)) = [0 0]x1 >= [0 0]x1 = a(c(x1)) problem: strict: a(b(x1)) -> b(a(x1)) weak: a(x1) -> b(c(x1)) b(c(x1)) -> a(c(x1)) Matrix Interpretation Processor: dim=2 interpretation: [1 2] [0] [a](x0) = [0 2]x0 + [1], [0] [b](x0) = x0 + [1], [1 0] [c](x0) = [0 0]x0 orientation: [1 2] [2] [1 2] [0] a(b(x1)) = [0 2]x1 + [3] >= [0 2]x1 + [2] = b(a(x1)) [1 2] [0] [1 0] [0] a(x1) = [0 2]x1 + [1] >= [0 0]x1 + [1] = b(c(x1)) [1 0] [0] [1 0] [0] b(c(x1)) = [0 0]x1 + [1] >= [0 0]x1 + [1] = a(c(x1)) problem: strict: weak: a(x1) -> b(c(x1)) b(c(x1)) -> a(c(x1)) Qed