a__f f a c f g f a mark f X a__f mark X mark a a mark c X c X mark g X g mark X a__f X f X 2.2 mark f X mark X mark g X mark X mark f X a__f mark X true mark g X mark X mark f X mark X true a 0 0 a__f 1 0 c 1 0 f 1 1 1 mark 1 1 0 mark 1 0 a__f 1 0 g 1 1 1 mark f X a__f mark X false NaTT certifiable-1.6