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