YES Problem: b(b(x1)) -> c(d(x1)) c(c(x1)) -> d(d(d(x1))) c(x1) -> g(x1) d(d(x1)) -> c(f(x1)) d(d(d(x1))) -> g(c(x1)) f(x1) -> a(g(x1)) g(x1) -> d(a(b(x1))) g(g(x1)) -> b(c(x1)) Proof: Arctic Interpretation Processor: dimension: 2 interpretation: [0 -&] [a](x0) = [-& -&]x0, [0 1 ] [f](x0) = [-& -&]x0, [0 1] [g](x0) = [1 3]x0, [0 1] [c](x0) = [1 3]x0, [0 0] [d](x0) = [0 2]x0, [0 1] [b](x0) = [2 3]x0 orientation: [3 4] [1 3] b(b(x1)) = [5 6]x1 >= [3 5]x1 = c(d(x1)) [2 4] [2 4] c(c(x1)) = [4 6]x1 >= [4 6]x1 = d(d(d(x1))) [0 1] [0 1] c(x1) = [1 3]x1 >= [1 3]x1 = g(x1) [0 2] [0 1] d(d(x1)) = [2 4]x1 >= [1 2]x1 = c(f(x1)) [2 4] [2 4] d(d(d(x1))) = [4 6]x1 >= [4 6]x1 = g(c(x1)) [0 1 ] [0 1 ] f(x1) = [-& -&]x1 >= [-& -&]x1 = a(g(x1)) [0 1] [0 1] g(x1) = [1 3]x1 >= [0 1]x1 = d(a(b(x1))) [2 4] [2 4] g(g(x1)) = [4 6]x1 >= [4 6]x1 = b(c(x1)) problem: c(c(x1)) -> d(d(d(x1))) c(x1) -> g(x1) d(d(x1)) -> c(f(x1)) d(d(d(x1))) -> g(c(x1)) f(x1) -> a(g(x1)) g(x1) -> d(a(b(x1))) g(g(x1)) -> b(c(x1)) Arctic Interpretation Processor: dimension: 2 interpretation: [0 -&] [a](x0) = [-& -&]x0, [0 0 ] [f](x0) = [-& 0 ]x0, [0 0] [g](x0) = [1 1]x0, [0 0] [c](x0) = [1 2]x0, [0 0] [d](x0) = [0 1]x0, [0 -&] [b](x0) = [0 -&]x0 orientation: [1 2] [1 2] c(c(x1)) = [3 4]x1 >= [2 3]x1 = d(d(d(x1))) [0 0] [0 0] c(x1) = [1 2]x1 >= [1 1]x1 = g(x1) [0 1] [0 0] d(d(x1)) = [1 2]x1 >= [1 2]x1 = c(f(x1)) [1 2] [1 2] d(d(d(x1))) = [2 3]x1 >= [2 3]x1 = g(c(x1)) [0 0 ] [0 0 ] f(x1) = [-& 0 ]x1 >= [-& -&]x1 = a(g(x1)) [0 0] [0 -&] g(x1) = [1 1]x1 >= [0 -&]x1 = d(a(b(x1))) [1 1] [0 0] g(g(x1)) = [2 2]x1 >= [0 0]x1 = b(c(x1)) problem: c(c(x1)) -> d(d(d(x1))) c(x1) -> g(x1) d(d(x1)) -> c(f(x1)) d(d(d(x1))) -> g(c(x1)) f(x1) -> a(g(x1)) g(x1) -> d(a(b(x1))) Arctic Interpretation Processor: dimension: 2 interpretation: [0 -&] [a](x0) = [0 -&]x0, [0 -&] [f](x0) = [0 -&]x0, [0 -&] [g](x0) = [2 0 ]x0, [2 0] [c](x0) = [2 3]x0, [0 0] [d](x0) = [2 1]x0, [0 -&] [b](x0) = [0 0 ]x0 orientation: [4 3] [3 2] c(c(x1)) = [5 6]x1 >= [4 3]x1 = d(d(d(x1))) [2 0] [0 -&] c(x1) = [2 3]x1 >= [2 0 ]x1 = g(x1) [2 1] [2 -&] d(d(x1)) = [3 2]x1 >= [3 -&]x1 = c(f(x1)) [3 2] [2 0] d(d(d(x1))) = [4 3]x1 >= [4 3]x1 = g(c(x1)) [0 -&] [0 -&] f(x1) = [0 -&]x1 >= [0 -&]x1 = a(g(x1)) [0 -&] [0 -&] g(x1) = [2 0 ]x1 >= [2 -&]x1 = d(a(b(x1))) problem: c(x1) -> g(x1) d(d(x1)) -> c(f(x1)) d(d(d(x1))) -> g(c(x1)) f(x1) -> a(g(x1)) g(x1) -> d(a(b(x1))) Arctic Interpretation Processor: dimension: 2 interpretation: [0 -&] [a](x0) = [0 -&]x0, [0 -&] [f](x0) = [0 0 ]x0, [0 -&] [g](x0) = [1 0 ]x0, [0 0] [c](x0) = [1 1]x0, [0 0] [d](x0) = [0 1]x0, [0 -&] [b](x0) = [2 1 ]x0 orientation: [0 0] [0 -&] c(x1) = [1 1]x1 >= [1 0 ]x1 = g(x1) [0 1] [0 0] d(d(x1)) = [1 2]x1 >= [1 1]x1 = c(f(x1)) [1 2] [0 0] d(d(d(x1))) = [2 3]x1 >= [1 1]x1 = g(c(x1)) [0 -&] [0 -&] f(x1) = [0 0 ]x1 >= [0 -&]x1 = a(g(x1)) [0 -&] [0 -&] g(x1) = [1 0 ]x1 >= [1 -&]x1 = d(a(b(x1))) problem: c(x1) -> g(x1) d(d(x1)) -> c(f(x1)) f(x1) -> a(g(x1)) g(x1) -> d(a(b(x1))) Arctic Interpretation Processor: dimension: 2 interpretation: [0 -&] [a](x0) = [0 -&]x0, [0 0] [f](x0) = [0 1]x0, [0 -&] [g](x0) = [1 -&]x0, [1 0] [c](x0) = [2 0]x0, [0 0] [d](x0) = [1 1]x0, [0 -&] [b](x0) = [2 0 ]x0 orientation: [1 0] [0 -&] c(x1) = [2 0]x1 >= [1 -&]x1 = g(x1) [1 1] [1 1] d(d(x1)) = [2 2]x1 >= [2 2]x1 = c(f(x1)) [0 0] [0 -&] f(x1) = [0 1]x1 >= [0 -&]x1 = a(g(x1)) [0 -&] [0 -&] g(x1) = [1 -&]x1 >= [1 -&]x1 = d(a(b(x1))) problem: d(d(x1)) -> c(f(x1)) f(x1) -> a(g(x1)) g(x1) -> d(a(b(x1))) Arctic Interpretation Processor: dimension: 2 interpretation: [0 0 ] [a](x0) = [-& 0 ]x0, [2 2] [f](x0) = [2 2]x0, [2 2] [g](x0) = [2 2]x0, [0 0 ] [c](x0) = [-& -&]x0, [0 2] [d](x0) = [1 2]x0, [0 1] [b](x0) = [0 0]x0 orientation: [3 4] [2 2 ] d(d(x1)) = [3 4]x1 >= [-& -&]x1 = c(f(x1)) [2 2] [2 2] f(x1) = [2 2]x1 >= [2 2]x1 = a(g(x1)) [2 2] [2 2] g(x1) = [2 2]x1 >= [2 2]x1 = d(a(b(x1))) problem: f(x1) -> a(g(x1)) g(x1) -> d(a(b(x1))) Arctic Interpretation Processor: dimension: 3 interpretation: [0 0 0 ] [a](x0) = [-& 0 0 ]x0 [0 -& -&] , [1 1 1] [f](x0) = [1 1 1]x0 [1 1 1] , [0 0 0] [g](x0) = [0 0 0]x0 [0 0 0] , [0 0 0 ] [d](x0) = [0 0 0 ]x0 [-& -& 0 ] , [0 0 0] [b](x0) = [0 0 0]x0 [0 0 0] orientation: [1 1 1] [0 0 0] f(x1) = [1 1 1]x1 >= [0 0 0]x1 = a(g(x1)) [1 1 1] [0 0 0] [0 0 0] [0 0 0] g(x1) = [0 0 0]x1 >= [0 0 0]x1 = d(a(b(x1))) [0 0 0] [0 0 0] problem: g(x1) -> d(a(b(x1))) Arctic Interpretation Processor: dimension: 3 interpretation: [0 0 0 ] [a](x0) = [0 0 0 ]x0 [0 0 -&] , [2 1 3] [g](x0) = [2 1 3]x0 [2 2 0] , [0 0 0 ] [d](x0) = [-& 0 -&]x0 [-& -& 0 ] , [1 0 -&] [b](x0) = [1 0 -&]x0 [-& 0 2 ] orientation: [2 1 3] [1 0 2 ] g(x1) = [2 1 3]x1 >= [1 0 2 ]x1 = d(a(b(x1))) [2 2 0] [1 0 -&] problem: Qed