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