YES Problem: a(a(x1)) -> c(b(a(b(a(x1))))) b(a(b(x1))) -> b(x1) a(a(a(x1))) -> c(c(a(x1))) c(c(x1)) -> a(b(c(b(a(x1))))) a(c(a(x1))) -> c(c(a(x1))) c(a(c(x1))) -> a(a(c(x1))) Proof: String Reversal Processor: a(a(x1)) -> a(b(a(b(c(x1))))) b(a(b(x1))) -> b(x1) a(a(a(x1))) -> a(c(c(x1))) c(c(x1)) -> a(b(c(b(a(x1))))) a(c(a(x1))) -> a(c(c(x1))) c(a(c(x1))) -> c(a(a(x1))) Matrix Interpretation Processor: dim=2 interpretation: [1 2] [0] [c](x0) = [0 0]x0 + [1], [1 1] [b](x0) = [0 0]x0, [1 2] [0] [a](x0) = [0 0]x0 + [1] orientation: [1 2] [2] [1 2] [2] a(a(x1)) = [0 0]x1 + [1] >= [0 0]x1 + [1] = a(b(a(b(c(x1))))) [1 1] [1] [1 1] b(a(b(x1))) = [0 0]x1 + [0] >= [0 0]x1 = b(x1) [1 2] [4] [1 2] [4] a(a(a(x1))) = [0 0]x1 + [1] >= [0 0]x1 + [1] = a(c(c(x1))) [1 2] [2] [1 2] [2] c(c(x1)) = [0 0]x1 + [1] >= [0 0]x1 + [1] = a(b(c(b(a(x1))))) [1 2] [4] [1 2] [4] a(c(a(x1))) = [0 0]x1 + [1] >= [0 0]x1 + [1] = a(c(c(x1))) [1 2] [4] [1 2] [4] c(a(c(x1))) = [0 0]x1 + [1] >= [0 0]x1 + [1] = c(a(a(x1))) problem: a(a(x1)) -> a(b(a(b(c(x1))))) a(a(a(x1))) -> a(c(c(x1))) c(c(x1)) -> a(b(c(b(a(x1))))) a(c(a(x1))) -> a(c(c(x1))) c(a(c(x1))) -> c(a(a(x1))) String Reversal Processor: a(a(x1)) -> c(b(a(b(a(x1))))) a(a(a(x1))) -> c(c(a(x1))) c(c(x1)) -> a(b(c(b(a(x1))))) a(c(a(x1))) -> c(c(a(x1))) c(a(c(x1))) -> a(a(c(x1))) Matrix Interpretation Processor: dim=3 interpretation: [1 0 1] [0] [c](x0) = [0 0 0]x0 + [0] [0 0 0] [1], [1 0 0] [b](x0) = [0 0 0]x0 [0 0 0] , [1 0 1] [0] [a](x0) = [0 0 0]x0 + [0] [0 0 0] [1] orientation: [1 0 1] [1] [1 0 1] [0] a(a(x1)) = [0 0 0]x1 + [0] >= [0 0 0]x1 + [0] = c(b(a(b(a(x1))))) [0 0 0] [1] [0 0 0] [1] [1 0 1] [2] [1 0 1] [2] a(a(a(x1))) = [0 0 0]x1 + [0] >= [0 0 0]x1 + [0] = c(c(a(x1))) [0 0 0] [1] [0 0 0] [1] [1 0 1] [1] [1 0 1] [0] c(c(x1)) = [0 0 0]x1 + [0] >= [0 0 0]x1 + [0] = a(b(c(b(a(x1))))) [0 0 0] [1] [0 0 0] [1] [1 0 1] [2] [1 0 1] [2] a(c(a(x1))) = [0 0 0]x1 + [0] >= [0 0 0]x1 + [0] = c(c(a(x1))) [0 0 0] [1] [0 0 0] [1] [1 0 1] [2] [1 0 1] [2] c(a(c(x1))) = [0 0 0]x1 + [0] >= [0 0 0]x1 + [0] = a(a(c(x1))) [0 0 0] [1] [0 0 0] [1] problem: a(a(a(x1))) -> c(c(a(x1))) a(c(a(x1))) -> c(c(a(x1))) c(a(c(x1))) -> a(a(c(x1))) DP Processor: DPs: a#(a(a(x1))) -> c#(a(x1)) a#(a(a(x1))) -> c#(c(a(x1))) a#(c(a(x1))) -> c#(c(a(x1))) c#(a(c(x1))) -> a#(a(c(x1))) TRS: a(a(a(x1))) -> c(c(a(x1))) a(c(a(x1))) -> c(c(a(x1))) c(a(c(x1))) -> a(a(c(x1))) TDG Processor: DPs: a#(a(a(x1))) -> c#(a(x1)) a#(a(a(x1))) -> c#(c(a(x1))) a#(c(a(x1))) -> c#(c(a(x1))) c#(a(c(x1))) -> a#(a(c(x1))) TRS: a(a(a(x1))) -> c(c(a(x1))) a(c(a(x1))) -> c(c(a(x1))) c(a(c(x1))) -> a(a(c(x1))) graph: c#(a(c(x1))) -> a#(a(c(x1))) -> a#(c(a(x1))) -> c#(c(a(x1))) c#(a(c(x1))) -> a#(a(c(x1))) -> a#(a(a(x1))) -> c#(c(a(x1))) c#(a(c(x1))) -> a#(a(c(x1))) -> a#(a(a(x1))) -> c#(a(x1)) a#(c(a(x1))) -> c#(c(a(x1))) -> c#(a(c(x1))) -> a#(a(c(x1))) a#(a(a(x1))) -> c#(c(a(x1))) -> c#(a(c(x1))) -> a#(a(c(x1))) a#(a(a(x1))) -> c#(a(x1)) -> c#(a(c(x1))) -> a#(a(c(x1))) Arctic Interpretation Processor: dimension: 1 interpretation: [c#](x0) = 1x0, [a#](x0) = 1x0, [c](x0) = 1x0, [a](x0) = 1x0 orientation: a#(a(a(x1))) = 3x1 >= 2x1 = c#(a(x1)) a#(a(a(x1))) = 3x1 >= 3x1 = c#(c(a(x1))) a#(c(a(x1))) = 3x1 >= 3x1 = c#(c(a(x1))) c#(a(c(x1))) = 3x1 >= 3x1 = a#(a(c(x1))) a(a(a(x1))) = 3x1 >= 3x1 = c(c(a(x1))) a(c(a(x1))) = 3x1 >= 3x1 = c(c(a(x1))) c(a(c(x1))) = 3x1 >= 3x1 = a(a(c(x1))) problem: DPs: a#(a(a(x1))) -> c#(c(a(x1))) a#(c(a(x1))) -> c#(c(a(x1))) c#(a(c(x1))) -> a#(a(c(x1))) TRS: a(a(a(x1))) -> c(c(a(x1))) a(c(a(x1))) -> c(c(a(x1))) c(a(c(x1))) -> a(a(c(x1))) EDG Processor: DPs: a#(a(a(x1))) -> c#(c(a(x1))) a#(c(a(x1))) -> c#(c(a(x1))) c#(a(c(x1))) -> a#(a(c(x1))) TRS: a(a(a(x1))) -> c(c(a(x1))) a(c(a(x1))) -> c(c(a(x1))) c(a(c(x1))) -> a(a(c(x1))) graph: c#(a(c(x1))) -> a#(a(c(x1))) -> a#(a(a(x1))) -> c#(c(a(x1))) c#(a(c(x1))) -> a#(a(c(x1))) -> a#(c(a(x1))) -> c#(c(a(x1))) a#(c(a(x1))) -> c#(c(a(x1))) -> c#(a(c(x1))) -> a#(a(c(x1))) a#(a(a(x1))) -> c#(c(a(x1))) -> c#(a(c(x1))) -> a#(a(c(x1))) Arctic Interpretation Processor: dimension: 2 interpretation: [c#](x0) = [-4 0 ]x0 + [0], [a#](x0) = [-1 -&]x0 + [0], [0 1 ] [0] [c](x0) = [-& 0 ]x0 + [0], [-& 1 ] [0] [a](x0) = [0 0 ]x0 + [1] orientation: a#(a(a(x1))) = [0 0]x1 + [1] >= [0 0]x1 + [1] = c#(c(a(x1))) a#(c(a(x1))) = [0 0]x1 + [1] >= [0 0]x1 + [1] = c#(c(a(x1))) c#(a(c(x1))) = [0 1]x1 + [1] >= [-& 0 ]x1 + [0] = a#(a(c(x1))) [1 2] [2] [1 1] [2] a(a(a(x1))) = [1 1]x1 + [2] >= [0 0]x1 + [1] = c(c(a(x1))) [1 1] [2] [1 1] [2] a(c(a(x1))) = [1 1]x1 + [2] >= [0 0]x1 + [1] = c(c(a(x1))) [1 2] [2] [1 2] [2] c(a(c(x1))) = [0 1]x1 + [1] >= [0 1]x1 + [1] = a(a(c(x1))) problem: DPs: a#(a(a(x1))) -> c#(c(a(x1))) a#(c(a(x1))) -> c#(c(a(x1))) TRS: a(a(a(x1))) -> c(c(a(x1))) a(c(a(x1))) -> c(c(a(x1))) c(a(c(x1))) -> a(a(c(x1))) EDG Processor: DPs: a#(a(a(x1))) -> c#(c(a(x1))) a#(c(a(x1))) -> c#(c(a(x1))) TRS: a(a(a(x1))) -> c(c(a(x1))) a(c(a(x1))) -> c(c(a(x1))) c(a(c(x1))) -> a(a(c(x1))) graph: Qed