YES Problem: strict: f(g(x)) -> x weak: a() -> h(g(f(a()))) Proof: Arctic Interpretation Processor: dimension: 4 interpretation: [0 -& -& 0 ] [0 1 1 1 ] [f](x0) = [0 0 -& 0 ]x0 [-& -& 0 0 ] , [0 -& -& -&] [0 -& -& -&] [h](x0) = [-& -& -& -&]x0 [0 0 -& -&] , [0 -& 0 0 ] [-& -& 0 0 ] [g](x0) = [0 -& 0 1 ]x0 [1 0 1 1 ] , [0] [0] [a] = [0] [0] orientation: [1 0 1 1] [2 1 2 2] f(g(x)) = [1 0 1 1]x >= x = x [1 0 1 1] [0] [0 ] [0] [0 ] a() = [0] >= [-&] = h(g(f(a()))) [0] [0 ] problem: strict: weak: a() -> h(g(f(a()))) Qed