YES Problem: a(a(b(b(x1)))) -> b(b(b(a(a(a(x1)))))) Proof: DP Processor: DPs: a#(a(b(b(x1)))) -> a#(x1) a#(a(b(b(x1)))) -> a#(a(x1)) a#(a(b(b(x1)))) -> a#(a(a(x1))) TRS: a(a(b(b(x1)))) -> b(b(b(a(a(a(x1)))))) Matrix Interpretation Processor: dim=3 interpretation: [a#](x0) = [0 0 2]x0, [0 0 2] [a](x0) = [0 0 1]x0 [0 1 0] , [0 1 2] [2] [b](x0) = [1 0 0]x0 + [0] [0 0 0] [0] orientation: a#(a(b(b(x1)))) = [0 2 4]x1 + [4] >= [0 0 2]x1 = a#(x1) a#(a(b(b(x1)))) = [0 2 4]x1 + [4] >= [0 2 0]x1 = a#(a(x1)) a#(a(b(b(x1)))) = [0 2 4]x1 + [4] >= [0 0 2]x1 = a#(a(a(x1))) [0 2 4] [4] [0 2 1] [4] a(a(b(b(x1)))) = [0 1 2]x1 + [2] >= [0 0 2]x1 + [2] = b(b(b(a(a(a(x1)))))) [0 0 0] [0] [0 0 0] [0] problem: DPs: TRS: a(a(b(b(x1)))) -> b(b(b(a(a(a(x1)))))) Qed