YES Problem: a(a(x1)) -> b(b(c(x1))) a(c(x1)) -> x1 c(b(x1)) -> a(c(a(x1))) Proof: String Reversal Processor: a(a(x1)) -> c(b(b(x1))) c(a(x1)) -> x1 b(c(x1)) -> a(c(a(x1))) DP Processor: DPs: a#(a(x1)) -> b#(x1) a#(a(x1)) -> b#(b(x1)) a#(a(x1)) -> c#(b(b(x1))) b#(c(x1)) -> a#(x1) b#(c(x1)) -> c#(a(x1)) b#(c(x1)) -> a#(c(a(x1))) TRS: a(a(x1)) -> c(b(b(x1))) c(a(x1)) -> x1 b(c(x1)) -> a(c(a(x1))) TDG Processor: DPs: a#(a(x1)) -> b#(x1) a#(a(x1)) -> b#(b(x1)) a#(a(x1)) -> c#(b(b(x1))) b#(c(x1)) -> a#(x1) b#(c(x1)) -> c#(a(x1)) b#(c(x1)) -> a#(c(a(x1))) TRS: a(a(x1)) -> c(b(b(x1))) c(a(x1)) -> x1 b(c(x1)) -> a(c(a(x1))) graph: b#(c(x1)) -> a#(c(a(x1))) -> a#(a(x1)) -> c#(b(b(x1))) b#(c(x1)) -> a#(c(a(x1))) -> a#(a(x1)) -> b#(b(x1)) b#(c(x1)) -> a#(c(a(x1))) -> a#(a(x1)) -> b#(x1) b#(c(x1)) -> a#(x1) -> a#(a(x1)) -> c#(b(b(x1))) b#(c(x1)) -> a#(x1) -> a#(a(x1)) -> b#(b(x1)) b#(c(x1)) -> a#(x1) -> a#(a(x1)) -> b#(x1) a#(a(x1)) -> b#(b(x1)) -> b#(c(x1)) -> a#(c(a(x1))) a#(a(x1)) -> b#(b(x1)) -> b#(c(x1)) -> c#(a(x1)) a#(a(x1)) -> b#(b(x1)) -> b#(c(x1)) -> a#(x1) a#(a(x1)) -> b#(x1) -> b#(c(x1)) -> a#(c(a(x1))) a#(a(x1)) -> b#(x1) -> b#(c(x1)) -> c#(a(x1)) a#(a(x1)) -> b#(x1) -> b#(c(x1)) -> a#(x1) SCC Processor: #sccs: 1 #rules: 4 #arcs: 12/36 DPs: b#(c(x1)) -> a#(c(a(x1))) a#(a(x1)) -> b#(x1) b#(c(x1)) -> a#(x1) a#(a(x1)) -> b#(b(x1)) TRS: a(a(x1)) -> c(b(b(x1))) c(a(x1)) -> x1 b(c(x1)) -> a(c(a(x1))) Arctic Interpretation Processor: dimension: 3 usable rules: a(a(x1)) -> c(b(b(x1))) c(a(x1)) -> x1 b(c(x1)) -> a(c(a(x1))) interpretation: [b#](x0) = [-& 0 0 ]x0 + [0], [a#](x0) = [0 0 -&]x0 + [0], [-& 0 1 ] [0 ] [b](x0) = [-& 0 -&]x0 + [0 ] [-& 0 -&] [-&], [-& 0 0 ] [0] [c](x0) = [0 0 0 ]x0 + [0] [0 1 0 ] [1], [0 1 0 ] [1] [a](x0) = [0 -& -&]x0 + [0] [0 -& -&] [0] orientation: b#(c(x1)) = [0 1 0]x1 + [1] >= [0 1 0]x1 + [1] = a#(c(a(x1))) a#(a(x1)) = [0 1 0]x1 + [1] >= [-& 0 0 ]x1 + [0] = b#(x1) b#(c(x1)) = [0 1 0]x1 + [1] >= [0 0 -&]x1 + [0] = a#(x1) a#(a(x1)) = [0 1 0]x1 + [1] >= [-& 0 -&]x1 + [0] = b#(b(x1)) [1 1 0] [1] [-& 0 -&] [0] a(a(x1)) = [0 1 0]x1 + [1] >= [-& 1 -&]x1 + [0] = c(b(b(x1))) [0 1 0] [1] [-& 1 -&] [1] [0 -& -&] [0] c(a(x1)) = [0 1 0 ]x1 + [1] >= x1 = x1 [1 1 0 ] [1] [1 2 1] [2] [1 2 1 ] [2] b(c(x1)) = [0 0 0]x1 + [0] >= [0 -& -&]x1 + [0] = a(c(a(x1))) [0 0 0] [0] [0 -& -&] [0] problem: DPs: b#(c(x1)) -> a#(c(a(x1))) a#(a(x1)) -> b#(x1) b#(c(x1)) -> a#(x1) TRS: a(a(x1)) -> c(b(b(x1))) c(a(x1)) -> x1 b(c(x1)) -> a(c(a(x1))) Restore Modifier: DPs: b#(c(x1)) -> a#(c(a(x1))) a#(a(x1)) -> b#(x1) b#(c(x1)) -> a#(x1) TRS: a(a(x1)) -> c(b(b(x1))) c(a(x1)) -> x1 b(c(x1)) -> a(c(a(x1))) EDG Processor: DPs: b#(c(x1)) -> a#(c(a(x1))) a#(a(x1)) -> b#(x1) b#(c(x1)) -> a#(x1) TRS: a(a(x1)) -> c(b(b(x1))) c(a(x1)) -> x1 b(c(x1)) -> a(c(a(x1))) graph: b#(c(x1)) -> a#(c(a(x1))) -> a#(a(x1)) -> b#(x1) b#(c(x1)) -> a#(x1) -> a#(a(x1)) -> b#(x1) a#(a(x1)) -> b#(x1) -> b#(c(x1)) -> a#(x1) a#(a(x1)) -> b#(x1) -> b#(c(x1)) -> a#(c(a(x1))) Arctic Interpretation Processor: dimension: 3 usable rules: a(a(x1)) -> c(b(b(x1))) c(a(x1)) -> x1 b(c(x1)) -> a(c(a(x1))) interpretation: [b#](x0) = [-& 0 -&]x0 + [0], [a#](x0) = [0 -& -&]x0, [-& 0 1 ] [0] [b](x0) = [-& -& 0 ]x0 + [0] [-& 0 -&] [0], [-& 0 0 ] [0] [c](x0) = [0 0 0 ]x0 + [1] [0 1 0 ] [1], [0 1 0 ] [1] [a](x0) = [0 0 -&]x0 + [0] [0 -& -&] [1] orientation: b#(c(x1)) = [0 0 0]x1 + [1] >= [0 0 -&]x1 + [1] = a#(c(a(x1))) a#(a(x1)) = [0 1 0]x1 + [1] >= [-& 0 -&]x1 + [0] = b#(x1) b#(c(x1)) = [0 0 0]x1 + [1] >= [0 -& -&]x1 = a#(x1) [1 1 0] [1] [-& 0 0 ] [0] a(a(x1)) = [0 1 0]x1 + [1] >= [-& 1 0 ]x1 + [1] = c(b(b(x1))) [0 1 0] [1] [-& 1 0 ] [1] [0 0 -&] [1] c(a(x1)) = [0 1 0 ]x1 + [1] >= x1 = x1 [1 1 0 ] [1] [1 2 1] [2] [1 2 1 ] [2] b(c(x1)) = [0 1 0]x1 + [1] >= [0 1 0 ]x1 + [1] = a(c(a(x1))) [0 0 0] [1] [0 0 -&] [1] problem: DPs: b#(c(x1)) -> a#(c(a(x1))) b#(c(x1)) -> a#(x1) TRS: a(a(x1)) -> c(b(b(x1))) c(a(x1)) -> x1 b(c(x1)) -> a(c(a(x1))) Restore Modifier: DPs: b#(c(x1)) -> a#(c(a(x1))) b#(c(x1)) -> a#(x1) TRS: a(a(x1)) -> c(b(b(x1))) c(a(x1)) -> x1 b(c(x1)) -> a(c(a(x1))) EDG Processor: DPs: b#(c(x1)) -> a#(c(a(x1))) b#(c(x1)) -> a#(x1) TRS: a(a(x1)) -> c(b(b(x1))) c(a(x1)) -> x1 b(c(x1)) -> a(c(a(x1))) graph: Qed