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