YES Problem: a(b(x1)) -> b(a(x1)) b(a(x1)) -> a(c(b(x1))) Proof: Arctic Interpretation Processor: dimension: 2 interpretation: [0 -&] [c](x0) = [0 -&]x0, [0 0] [a](x0) = [1 1]x0, [0 0] [b](x0) = [1 1]x0 orientation: [1 1] [1 1] a(b(x1)) = [2 2]x1 >= [2 2]x1 = b(a(x1)) [1 1] [0 0] b(a(x1)) = [2 2]x1 >= [1 1]x1 = a(c(b(x1))) problem: a(b(x1)) -> b(a(x1)) KBO Processor: weight function: w0 = 1 w(a) = w(b) = 1 precedence: a > b problem: Qed