Xuanxuan Qijing Problem 91: Black to play and kill
玄玄棋经 · Problem 91 of 347 · Double snapback
White's stones on the top side are in two parts with a narrow space between them. Black has to give up stones on both sides, and the order of the moves matters.
How to solve it
White's group on the top side has a left half and a right half, and its eye space lies between them. Black starts by wedging into the gap at D18.
White plays D17 from below and Black extends to E18. White then takes the first-line point D19, which leaves Black's two stones with a single liberty.
Black does not save them. Black plays inside the left half with B19, White answers at A18, and Black adds C19, offering two more stones.
Now both pairs of black stones can be captured, but neither capture helps White: Black throws in again and takes back a larger white group. Sensei's Library calls the result a double snapback and notes that the order of the moves is important.
Main line
- 1. Black D18
- 2. White D17
- 3. Black E18
- 4. White D19
- 5. Black B19
- 6. White A18
- 7. Black C19
Solution checked against Sensei's Library.
Play it out on the board
Place the stones yourself and see the refutation when you miss. All the Xuanxuan Qijing problems as quick lessons.