YES Problem: f(f(X)) -> f(g(f(g(f(X))))) f(g(f(X))) -> f(g(X)) Proof: Arctic Interpretation Processor: dimension: 2 interpretation: [0 -&] [g](x0) = [-& -&]x0, [0 0] [f](x0) = [1 2]x0 orientation: [1 2] [0 0] f(f(X)) = [3 4]X >= [1 1]X = f(g(f(g(f(X))))) [0 0] [0 -&] f(g(f(X))) = [1 1]X >= [1 -&]X = f(g(X)) problem: f(g(f(X))) -> f(g(X)) Arctic Interpretation Processor: dimension: 2 interpretation: [0 2] [g](x0) = [1 2]x0, [3 0 ] [f](x0) = [-& 2 ]x0 orientation: [6 7] [3 5] f(g(f(X))) = [6 6]X >= [3 4]X = f(g(X)) problem: Qed