YES Problem: strict: f(b(x),y) -> f(x,b(y)) f(x,a(y)) -> f(a(x),y) weak: f(x,y) -> f(a(x),y) f(x,y) -> f(x,b(y)) Proof: Matrix Interpretation Processor: dim=5 interpretation: [1 1 0 0 1] [1 0 1 0 1] [0] [1 1 0 1 0] [0 0 0 0 0] [0] [f](x0, x1) = [1 0 0 0 0]x0 + [1 0 1 0 1]x1 + [0] [0 0 0 0 0] [0 0 0 0 0] [0] [1 1 0 0 0] [0 0 0 0 0] [1], [1 0 0 0 1] [0] [0 1 0 1 1] [1] [b](x0) = [0 0 0 0 0]x0 + [0] [0 0 0 1 1] [0] [0 0 1 0 0] [0], [1 0 0 0 0] [0] [0 0 0 0 0] [0] [a](x0) = [0 0 1 0 1]x0 + [1] [0 1 0 0 0] [0] [0 0 0 0 0] [0] orientation: [1 1 1 1 2] [1 0 1 0 1] [1] [1 1 0 0 1] [1 0 1 0 1] [0] [1 1 0 2 3] [0 0 0 0 0] [1] [1 1 0 1 0] [0 0 0 0 0] [0] f(b(x),y) = [1 0 0 0 1]x + [1 0 1 0 1]y + [0] >= [1 0 0 0 0]x + [1 0 1 0 1]y + [0] = f(x,b(y)) [0 0 0 0 0] [0 0 0 0 0] [0] [0 0 0 0 0] [0 0 0 0 0] [0] [1 1 0 1 2] [0 0 0 0 0] [2] [1 1 0 0 0] [0 0 0 0 0] [1] [1 1 0 0 1] [1 0 1 0 1] [1] [1 0 0 0 0] [1 0 1 0 1] [0] [1 1 0 1 0] [0 0 0 0 0] [0] [1 1 0 0 0] [0 0 0 0 0] [0] f(x,a(y)) = [1 0 0 0 0]x + [1 0 1 0 1]y + [1] >= [1 0 0 0 0]x + [1 0 1 0 1]y + [0] = f(a(x),y) [0 0 0 0 0] [0 0 0 0 0] [0] [0 0 0 0 0] [0 0 0 0 0] [0] [1 1 0 0 0] [0 0 0 0 0] [1] [1 0 0 0 0] [0 0 0 0 0] [1] [1 1 0 0 1] [1 0 1 0 1] [0] [1 0 0 0 0] [1 0 1 0 1] [0] [1 1 0 1 0] [0 0 0 0 0] [0] [1 1 0 0 0] [0 0 0 0 0] [0] f(x,y) = [1 0 0 0 0]x + [1 0 1 0 1]y + [0] >= [1 0 0 0 0]x + [1 0 1 0 1]y + [0] = f(a(x),y) [0 0 0 0 0] [0 0 0 0 0] [0] [0 0 0 0 0] [0 0 0 0 0] [0] [1 1 0 0 0] [0 0 0 0 0] [1] [1 0 0 0 0] [0 0 0 0 0] [1] [1 1 0 0 1] [1 0 1 0 1] [0] [1 1 0 0 1] [1 0 1 0 1] [0] [1 1 0 1 0] [0 0 0 0 0] [0] [1 1 0 1 0] [0 0 0 0 0] [0] f(x,y) = [1 0 0 0 0]x + [1 0 1 0 1]y + [0] >= [1 0 0 0 0]x + [1 0 1 0 1]y + [0] = f(x,b(y)) [0 0 0 0 0] [0 0 0 0 0] [0] [0 0 0 0 0] [0 0 0 0 0] [0] [1 1 0 0 0] [0 0 0 0 0] [1] [1 1 0 0 0] [0 0 0 0 0] [1] problem: strict: weak: f(x,y) -> f(a(x),y) f(x,y) -> f(x,b(y)) Qed