YES(?,O(n^2)) Problem: g(f(x),y) -> f(h(x,y)) h(x,y) -> g(x,f(y)) Proof: Matrix Interpretation Processor: dimension: 2 interpretation: [1 2] [1 0] [3] [h](x0, x1) = [0 1]x0 + [0 0]x1 + [0], [1 2] [1 0] [2] [g](x0, x1) = [0 1]x0 + [0 0]x1 + [0], [0] [f](x0) = x0 + [2] orientation: [1 2] [1 0] [6] [1 2] [1 0] [3] g(f(x),y) = [0 1]x + [0 0]y + [2] >= [0 1]x + [0 0]y + [2] = f(h(x,y)) [1 2] [1 0] [3] [1 2] [1 0] [2] h(x,y) = [0 1]x + [0 0]y + [0] >= [0 1]x + [0 0]y + [0] = g(x,f(y)) problem: Qed