Xuanxuan Qijing Problem 69: White to play and kill
玄玄棋经 · Problem 69 of 347 · First-line placement
Black's corner is nearly alive. A hane gets a ko, but there is something better: a placement on the first line, followed by moves that use Black's shortage of liberties.
How to solve it
White's placement at C19 on the first line is the tesuji. Black's strongest resistance is A18.
White continues with F19, answered at E19, and then E17. These are clever moves: after Black's B19 and White's E18, Black captures a stone with G19 but cannot connect at D19 for lack of liberties. White plays D19 and takes away the second eye.
If Black tries to enlarge the eye space with E17 instead, White's hane at A18 destroys the eye in the corner. After Black's B19, White's E19, Black's F19 and White's D19, Black is dead with a straight three.
The hane at A18 as a first move gets only a ko. Starting with E17 lets Black live, and extending to B19 on move 3 lets Black force a seki.
Main line
- 1. White C19
- 2. Black A18
- 3. White F19
- 4. Black E19
- 5. White E17
- 6. Black B19
- 7. White E18
- 8. Black G19
- 9. White D19
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.