a f a f x a x x a h x a f a g a f x 2.2 a h x a g a f x a h x a f x a h x a f a g a f x a f a f x a x x true a f a f x a x x a h x a f x true a 2 1 2 21238 h 0 1 f 0 1 a 2 2 0 g 0 0 a h x a f x a h x a f x false a h x a f a g a f x false a h x a g a f x false NaTT certifiable-1.6