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