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