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