b a a x1 a b c x1 c a x1 a c x1 c b x1 b a x1 L a a x1 L a b c x1 c R x1 b a R x1 2.2 c R x1 b a R x1 L a a x1 L a b c x1 L a a x1 b c x1 b a a x1 c x1 c b x1 b a x1 c a x1 c x1 L a a x1 c x1 b a a x1 b c x1 true L a a x1 L a b c x1 true Failed! NaTT certifiable-1.6