YES Problem: a(x1) -> b(c(x1)) a(b(x1)) -> b(a(x1)) d(c(x1)) -> d(a(x1)) a(c(x1)) -> c(a(x1)) Proof: Arctic Interpretation Processor: dimension: 2 interpretation: [0 0 ] [d](x0) = [-& -&]x0, [0 -&] [b](x0) = [-& -&]x0, [0 -&] [c](x0) = [1 1 ]x0, [0 -&] [a](x0) = [0 0 ]x0 orientation: [0 -&] [0 -&] a(x1) = [0 0 ]x1 >= [-& -&]x1 = b(c(x1)) [0 -&] [0 -&] a(b(x1)) = [0 -&]x1 >= [-& -&]x1 = b(a(x1)) [1 1 ] [0 0 ] d(c(x1)) = [-& -&]x1 >= [-& -&]x1 = d(a(x1)) [0 -&] [0 -&] a(c(x1)) = [1 1 ]x1 >= [1 1 ]x1 = c(a(x1)) problem: a(x1) -> b(c(x1)) a(b(x1)) -> b(a(x1)) a(c(x1)) -> c(a(x1)) Arctic Interpretation Processor: dimension: 2 interpretation: [0 0 ] [b](x0) = [0 -&]x0, [1 -&] [c](x0) = [-& 1 ]x0, [2 2] [a](x0) = [2 0]x0 orientation: [2 2] [1 1 ] a(x1) = [2 0]x1 >= [1 -&]x1 = b(c(x1)) [2 2] [2 2] a(b(x1)) = [2 2]x1 >= [2 2]x1 = b(a(x1)) [3 3] [3 3] a(c(x1)) = [3 1]x1 >= [3 1]x1 = c(a(x1)) problem: a(b(x1)) -> b(a(x1)) a(c(x1)) -> c(a(x1)) KBO Processor: weight function: w0 = 1 w(b) = w(c) = w(a) = 1 precedence: a > b ~ c problem: Qed