YES Problem: a(x1) -> x1 a(b(x1)) -> b(b(a(c(x1)))) b(b(x1)) -> x1 c(c(x1)) -> a(x1) Proof: DP Processor: DPs: a#(b(x1)) -> c#(x1) a#(b(x1)) -> a#(c(x1)) a#(b(x1)) -> b#(a(c(x1))) a#(b(x1)) -> b#(b(a(c(x1)))) c#(c(x1)) -> a#(x1) TRS: a(x1) -> x1 a(b(x1)) -> b(b(a(c(x1)))) b(b(x1)) -> x1 c(c(x1)) -> a(x1) TDG Processor: DPs: a#(b(x1)) -> c#(x1) a#(b(x1)) -> a#(c(x1)) a#(b(x1)) -> b#(a(c(x1))) a#(b(x1)) -> b#(b(a(c(x1)))) c#(c(x1)) -> a#(x1) TRS: a(x1) -> x1 a(b(x1)) -> b(b(a(c(x1)))) b(b(x1)) -> x1 c(c(x1)) -> a(x1) graph: c#(c(x1)) -> a#(x1) -> a#(b(x1)) -> b#(b(a(c(x1)))) c#(c(x1)) -> a#(x1) -> a#(b(x1)) -> b#(a(c(x1))) c#(c(x1)) -> a#(x1) -> a#(b(x1)) -> a#(c(x1)) c#(c(x1)) -> a#(x1) -> a#(b(x1)) -> c#(x1) a#(b(x1)) -> c#(x1) -> c#(c(x1)) -> a#(x1) a#(b(x1)) -> a#(c(x1)) -> a#(b(x1)) -> b#(b(a(c(x1)))) a#(b(x1)) -> a#(c(x1)) -> a#(b(x1)) -> b#(a(c(x1))) a#(b(x1)) -> a#(c(x1)) -> a#(b(x1)) -> a#(c(x1)) a#(b(x1)) -> a#(c(x1)) -> a#(b(x1)) -> c#(x1) SCC Processor: #sccs: 1 #rules: 3 #arcs: 9/25 DPs: c#(c(x1)) -> a#(x1) a#(b(x1)) -> c#(x1) a#(b(x1)) -> a#(c(x1)) TRS: a(x1) -> x1 a(b(x1)) -> b(b(a(c(x1)))) b(b(x1)) -> x1 c(c(x1)) -> a(x1) Arctic Interpretation Processor: dimension: 2 interpretation: [c#](x0) = [0 0]x0 + [1], [a#](x0) = [-& 0 ]x0 + [0], [0 1 ] [0] [c](x0) = [0 -&]x0 + [0], [-& 0 ] [0] [b](x0) = [0 0 ]x0 + [2], [0 1 ] [-&] [a](x0) = [-& 1 ]x0 + [0 ] orientation: c#(c(x1)) = [0 1]x1 + [1] >= [-& 0 ]x1 + [0] = a#(x1) a#(b(x1)) = [0 0]x1 + [2] >= [0 0]x1 + [1] = c#(x1) a#(b(x1)) = [0 0]x1 + [2] >= [0 -&]x1 + [0] = a#(c(x1)) [0 1 ] [-&] a(x1) = [-& 1 ]x1 + [0 ] >= x1 = x1 [1 1] [3] [1 1] [2] a(b(x1)) = [1 1]x1 + [3] >= [1 1]x1 + [2] = b(b(a(c(x1)))) [0 0] [2] b(b(x1)) = [0 0]x1 + [2] >= x1 = x1 [1 1] [1] [0 1 ] [-&] c(c(x1)) = [0 1]x1 + [0] >= [-& 1 ]x1 + [0 ] = a(x1) problem: DPs: a#(b(x1)) -> c#(x1) a#(b(x1)) -> a#(c(x1)) TRS: a(x1) -> x1 a(b(x1)) -> b(b(a(c(x1)))) b(b(x1)) -> x1 c(c(x1)) -> a(x1) EDG Processor: DPs: a#(b(x1)) -> c#(x1) a#(b(x1)) -> a#(c(x1)) TRS: a(x1) -> x1 a(b(x1)) -> b(b(a(c(x1)))) b(b(x1)) -> x1 c(c(x1)) -> a(x1) graph: a#(b(x1)) -> a#(c(x1)) -> a#(b(x1)) -> c#(x1) a#(b(x1)) -> a#(c(x1)) -> a#(b(x1)) -> a#(c(x1)) SCC Processor: #sccs: 1 #rules: 1 #arcs: 2/4 DPs: a#(b(x1)) -> a#(c(x1)) TRS: a(x1) -> x1 a(b(x1)) -> b(b(a(c(x1)))) b(b(x1)) -> x1 c(c(x1)) -> a(x1) Arctic Interpretation Processor: dimension: 3 interpretation: [a#](x0) = [0 -& -1]x0 + [0], [-& 0 -2] [0 ] [c](x0) = [0 1 0 ]x0 + [-&] [-& 1 -1] [1 ], [-1 1 -&] [1 ] [b](x0) = [-1 -& -2]x0 + [-&] [0 -& 0 ] [-&], [0 -2 0 ] [a](x0) = [1 0 0 ]x0 [1 -& 1 ] orientation: a#(b(x1)) = [-1 1 -1]x1 + [1] >= [-& 0 -2]x1 + [0] = a#(c(x1)) [0 -2 0 ] a(x1) = [1 0 0 ]x1 >= x1 = x1 [1 -& 1 ] [0 1 0] [1] [0 1 0] [1] a(b(x1)) = [0 2 0]x1 + [2] >= [0 1 0]x1 + [1] = b(b(a(c(x1)))) [1 2 1] [2] [1 2 1] [2] [0 0 -1] [1] b(b(x1)) = [-2 0 -2]x1 + [0] >= x1 = x1 [0 1 0 ] [1] [0 1 0] [0] [0 -2 0 ] c(c(x1)) = [1 2 1]x1 + [1] >= [1 0 0 ]x1 = a(x1) [1 2 1] [1] [1 -& 1 ] problem: DPs: TRS: a(x1) -> x1 a(b(x1)) -> b(b(a(c(x1)))) b(b(x1)) -> x1 c(c(x1)) -> a(x1) Qed