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 interpretation: [a#](x0) = [0 2]x0, [0 2] [b](x0) = [0 0]x0, [0 -&] [c](x0) = [-& -&]x0, [0 0] [a](x0) = [0 0]x0 orientation: a#(b(b(x1))) = [2 4]x1 >= [0 2]x1 = a#(x1) a#(b(b(x1))) = [2 4]x1 >= [2 2]x1 = a#(a(x1)) [0 0] [0 -&] a(x1) = [0 0]x1 >= [0 -&]x1 = b(c(x1)) [0 2] a(b(x1)) = [0 2]x1 >= x1 = x1 [2 2] [2 2] a(b(b(x1))) = [2 2]x1 >= [2 2]x1 = 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)))) Arctic Interpretation Processor: dimension: 2 interpretation: [a#](x0) = [1 0]x0 + [0], [-& 2 ] [0] [b](x0) = [0 -&]x0 + [0], [0 -&] [0 ] [c](x0) = [-& -&]x0 + [-&], [0 0] [0] [a](x0) = [0 0]x0 + [0] orientation: a#(b(b(x1))) = [3 2]x1 + [3] >= [1 1]x1 + [1] = a#(a(x1)) [0 0] [0] [-& -&] [0] a(x1) = [0 0]x1 + [0] >= [0 -&]x1 + [0] = b(c(x1)) [0 2] [0] a(b(x1)) = [0 2]x1 + [0] >= x1 = x1 [2 2] [2] [2 2] [2] a(b(b(x1))) = [2 2]x1 + [2] >= [2 2]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