YES Problem: a(b(a(x1))) -> b(b(b(b(x1)))) a(b(b(x1))) -> b(b(a(a(x1)))) Proof: DP Processor: DPs: a#(b(b(x1))) -> a#(x1) a#(b(b(x1))) -> a#(a(x1)) TRS: a(b(a(x1))) -> b(b(b(b(x1)))) a(b(b(x1))) -> b(b(a(a(x1)))) Matrix Interpretation Processor: dim=5 interpretation: [a#](x0) = [0 1 0 0 0]x0, [1 0 0 0 0] [0] [0 0 0 0 1] [1] [b](x0) = [0 1 0 0 0]x0 + [0] [1 0 1 0 0] [0] [0 1 0 0 0] [0], [1 0 0 0 0] [0] [0 1 0 0 0] [0] [a](x0) = [0 1 0 1 1]x0 + [0] [1 1 0 0 0] [0] [0 1 0 1 0] [1] orientation: a#(b(b(x1))) = [0 1 0 0 0]x1 + [1] >= [0 1 0 0 0]x1 = a#(x1) a#(b(b(x1))) = [0 1 0 0 0]x1 + [1] >= [0 1 0 0 0]x1 = a#(a(x1)) [1 0 0 0 0] [0] [1 0 0 0 0] [0] [0 1 0 1 0] [2] [0 1 0 0 0] [2] a(b(a(x1))) = [1 3 0 2 1]x1 + [2] >= [0 0 0 0 1]x1 + [2] = b(b(b(b(x1)))) [1 1 0 1 0] [2] [1 1 0 0 0] [1] [1 2 0 2 1] [3] [0 0 0 0 1] [2] [1 0 0 0 0] [0] [1 0 0 0 0] [0] [0 1 0 0 0] [1] [0 1 0 0 0] [1] a(b(b(x1))) = [1 2 0 0 1]x1 + [2] >= [1 2 0 0 0]x1 + [2] = b(b(a(a(x1)))) [1 1 0 0 0] [1] [1 1 0 0 0] [0] [1 2 0 0 0] [2] [1 2 0 0 0] [2] problem: DPs: TRS: a(b(a(x1))) -> b(b(b(b(x1)))) a(b(b(x1))) -> b(b(a(a(x1)))) Qed