YES Problem: a(a(b(x1))) -> c(b(a(a(a(x1))))) a(c(x1)) -> b(a(x1)) Proof: DP Processor: DPs: a#(a(b(x1))) -> a#(x1) a#(a(b(x1))) -> a#(a(x1)) a#(a(b(x1))) -> a#(a(a(x1))) a#(c(x1)) -> a#(x1) TRS: a(a(b(x1))) -> c(b(a(a(a(x1))))) a(c(x1)) -> b(a(x1)) Arctic Interpretation Processor: dimension: 2 interpretation: [a#](x0) = [2 0]x0, [1 0] [0] [c](x0) = [2 0]x0 + [2], [0 0 ] [0] [a](x0) = [-& 0 ]x0 + [0], [-& -&] [0] [b](x0) = [0 0 ]x0 + [2] orientation: a#(a(b(x1))) = [2 2]x1 + [4] >= [2 0]x1 = a#(x1) a#(a(b(x1))) = [2 2]x1 + [4] >= [2 2]x1 + [2] = a#(a(x1)) a#(a(b(x1))) = [2 2]x1 + [4] >= [2 2]x1 + [2] = a#(a(a(x1))) a#(c(x1)) = [3 2]x1 + [2] >= [2 0]x1 = a#(x1) [0 0] [2] [0 0] [2] a(a(b(x1))) = [0 0]x1 + [2] >= [0 0]x1 + [2] = c(b(a(a(a(x1))))) [2 0] [2] [-& -&] [0] a(c(x1)) = [2 0]x1 + [2] >= [0 0 ]x1 + [2] = b(a(x1)) problem: DPs: a#(a(b(x1))) -> a#(x1) a#(a(b(x1))) -> a#(a(x1)) a#(a(b(x1))) -> a#(a(a(x1))) TRS: a(a(b(x1))) -> c(b(a(a(a(x1))))) a(c(x1)) -> b(a(x1)) Matrix Interpretation Processor: dim=3 interpretation: [a#](x0) = [1 0 0]x0, [0 0 0] [0] [c](x0) = [2 2 1]x0 + [1] [0 0 0] [0], [0 0 1] [a](x0) = [2 0 0]x0 [0 1 0] , [0 0 0] [0] [b](x0) = [0 0 0]x0 + [0] [1 1 2] [1] orientation: a#(a(b(x1))) = [1 1 2]x1 + [1] >= [1 0 0]x1 = a#(x1) a#(a(b(x1))) = [1 1 2]x1 + [1] >= [0 0 1]x1 = a#(a(x1)) a#(a(b(x1))) = [1 1 2]x1 + [1] >= [0 1 0]x1 = a#(a(a(x1))) [0 0 0] [0] [0 0 0] [0] a(a(b(x1))) = [2 2 4]x1 + [2] >= [2 2 4]x1 + [2] = c(b(a(a(a(x1))))) [0 0 0] [0] [0 0 0] [0] [0 0 0] [0] [0 0 0] [0] a(c(x1)) = [0 0 0]x1 + [0] >= [0 0 0]x1 + [0] = b(a(x1)) [2 2 1] [1] [2 2 1] [1] problem: DPs: TRS: a(a(b(x1))) -> c(b(a(a(a(x1))))) a(c(x1)) -> b(a(x1)) Qed