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