The tiger pair — uncuttable
The pair (双) is two friendly stones side by side with the gap they jointly own — uncuttable, because anyone entering the gap is self-atari. It is the safest way to keep stones in touch: full liberties, both directions preserved, nothing for the opponent to bite. Weaker links — the diagonal contact and the knight's move — trade safety for speed and must be justified by the surrounding position. Here three stones stand one step from each other, and one move turns all of them into a single unbreakable group; finding such junction points is how one stone does the work of three. Black to play: the unifying stone.