YES Problem: b(c(x1)) -> a(x1) b(b(x1)) -> a(c(x1)) a(x1) -> c(b(x1)) c(c(c(x1))) -> b(x1) Proof: Arctic Interpretation Processor: dimension: 2 interpretation: [2 3] [a](x0) = [2 3]x0, [0 2] [b](x0) = [1 2]x0, [0 1] [c](x0) = [0 1]x0 orientation: [2 3] [2 3] b(c(x1)) = [2 3]x1 >= [2 3]x1 = a(x1) [3 4] [3 4] b(b(x1)) = [3 4]x1 >= [3 4]x1 = a(c(x1)) [2 3] [2 3] a(x1) = [2 3]x1 >= [2 3]x1 = c(b(x1)) [2 3] [0 2] c(c(c(x1))) = [2 3]x1 >= [1 2]x1 = b(x1) problem: b(c(x1)) -> a(x1) b(b(x1)) -> a(c(x1)) a(x1) -> c(b(x1)) Arctic Interpretation Processor: dimension: 2 interpretation: [1 1] [a](x0) = [0 1]x0, [1 1] [b](x0) = [1 0]x0, [0 0 ] [c](x0) = [-& -&]x0 orientation: [1 1] [1 1] b(c(x1)) = [1 1]x1 >= [0 1]x1 = a(x1) [2 2] [1 1] b(b(x1)) = [2 2]x1 >= [0 0]x1 = a(c(x1)) [1 1] [1 1 ] a(x1) = [0 1]x1 >= [-& -&]x1 = c(b(x1)) problem: b(c(x1)) -> a(x1) a(x1) -> c(b(x1)) KBO Processor: weight function: w0 = 1 w(a) = w(c) = 1 w(b) = 0 precedence: b > a > c problem: Qed