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