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: 3 interpretation: [1 -& 1 ] [g](x0) = [1 1 0 ]x0 [0 0 1 ] , [1 1 1 ] [f](x0) = [-& 1 0 ]x0 [1 0 1 ] orientation: [3 3 3] [2 2 2] f(g(f(X))) = [3 3 3]X >= [2 2 1]X = f(g(X)) [3 3 3] [2 1 2] problem: Qed