Xuanxuan Qijing Problem 57: Black to play and make a ko
玄玄棋经 · Problem 57 of 347 · Ko on the first line
The tiger can neither walk out nor make two eyes. Its only chance is a ko: use the first line, and aim to be the one who captures first.
How to solve it
This problem is titled 'Troubled Tiger Escapes Trap' (困虎脫穽勢): Black's long group is surrounded and has to find a way out. Black starts with H17, and White blocks at H18.
Black plays K19 on the first line. If White answers at L17, Black plays H19. After White's G18 and Black's J18, White captures with J19 and Black's K17 makes a ko, which Black takes first.
If White answers K19 at J19 instead, Black plays K17. White captures with L19, Black plays G19, and after White's G18 Black captures with J18. Again it is a ko that Black takes first.
Sensei's Library notes that starting with K19 also works, with similar variations.
Main line
- 1. Black H17
- 2. White H18
- 3. Black K19
- 4. White L17
- 5. Black H19
- 6. White G18
- 7. Black J18
- 8. White J19
- 9. Black K17
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.