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