f f x f g f x x f f x f h f x f x g x y y h x x g x 0 2.2 f f x h f x f x h x x g x 0 f f x f g f x x f f x f h f x f x f f x g f x x true f f x f h f x f x f f x f g f x x true h 2 23677 f 1 1 23678 0 0 1 h 2 0 f 1 1 0 g 2 0 g 2 2 23676 h x x g x 0 f f x f g f x x g x y y f f x f h f x f x f f x g f x x false f f x h f x f x false h x x g x 0 false NaTT certifiable-1.6