Kyu Exercise 7 Solution
Difficulty: Advanced
Keywords: Life & Death
Preamble:
![[Diagram]](../../diagrams/24/fae2f4fbaa085899e84a34951441088e.png) | Time is of the essence |
The marked black stones have only two turns of aji left in them - the first move is nearly certain to be ate.
![[Diagram]](../../diagrams/45/0d40cadf9eb5f16250ab418d94632c58.png) | Variation 'a' fails |
After this sequence up to , Black needs at least three turns to capture the eye - because strange things happen in the corner. Black must first connect before taking the corner liberty - and by then it's too late.
Dieter: When Black connects at , he dies in gote. White needn't play . Earlier, White can also answer with at , but in fact this leaves a ko threat behind, so answering at is probably correct.
![[Diagram]](../../diagrams/7/0658bf2a5d29bb55bece81cd55898863.png) | Variation 'b' fails |
Black now needs at least five turns to kill White - she could tenuki here without worry. dies in gote.
![[Diagram]](../../diagrams/45/fcd8acdfadb831a5ca0e636cf423548f.png) | Variation 'c' - success |
The only sequence. Black's win of this ko captures first the marked White stone, followed by the rest of the group. Notice that White captures first - but it's better than death. Question - so this is a two step ko?
unkx80: Yes, this is a two step ko. This is also the solution. If plays at , Black will catch all the white stones in a snapback at a.
![[Diagram]](../../diagrams/52/fa1147fbfc94132d9a720d7e739fd4da.png) | Variation c - success, continued |
Hattu (27k): I had a lot of trouble with this tsumego after counting up to the position after . I first discarded this variation - thinking that white stone at a next turn will win the battle without doubt. It's an important piece of knowledge to learn what is a ko threat and why they are important. is one of those: it threatens to escape with the black group in danger, so White has to defend with , or she won't benefit too much from winning the ko. This gives Black the chance to play at the marked stone, and even further at b next turn, if White can't come up with a decent ko threat to answer with.
Of course White will count the number of good ko threats in the board and look around the left border, and decide if playing at or a is better. If Black has more good threats than White, and the left edge was going to be black territory anyway, White could always just allow Black to escape down the left side with the play at a. At least White lives in the corner, and can build up good influence against the black stones which are running towards the lower right corner.
![[Diagram]](../../diagrams/46/b1090e98411336408a58f9544b0a7456.png) | Variation 'd' - failure |
As in Variation a, Black needs three turns in this variation, and dies in a similar fashion.
This is a copy of the living page
"Kyu Exercise 7 Solution" at
Sensei's Library.
2003 the Authors, published under the OpenContent License V1.0.
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