g s x f x f 0 s 0 f s x s s g x g 0 0 2.2 g s x f x f s x g x true f s x g x g s x f x true s 1 1 1 f 1 0 0 0 0 f 1 1 0 g 1 1 0 g 1 0 NaTT certifiable-1.6