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