Tsumego From Games 60 / Solutions3

Sub-page of TsumegoFromGames60

tderz: What could happen in these 2 positions?

imaginary position (1)  
imaginary position (1)  

Ed?: White seems beyond reasonable hope. 2 and 3 or 'a' and 'b' seem to be miai. White can probably dig up an unreasonable approach ko.

tderz: If W2 at b, it reverts to some variations below, if black cuts at B3. c and a are miai now. B3 at a would allow white to live in a favourable ko.

When I gave my friend a comment on the position at game move 173 (some moves earlier) - I asked him what the possible outcomes could be theoretically, but without calculating, just at a glance.

  • i) It could become local seki - each one eye => the center group is dead, the seki stops to be one => huge win for Black.
  • ii) It could become any type of ko
  • iii) White could live on her own
  • iv) the black black+square-stones could become captured (during ko or else)

Especially cases iii) and iv) have to be avoided.
In the game, not this position, Black has many more liberties (ok, that's calculating now), so any approach ko with 3 or more necessary moves is usually considered worth very little.

B3 at c, W-d?, B3 eye (W dead) is tempting, but white will resist with ko: B1, W2, Bc, W4->d.

imaginary position (2)  

Ed?: White is in trouble as black has 'a' or 'b'

imaginary position (2) Example 9 to left of 7  

tderz: I wanted to see espec. W4.

imaginary position (2)  

tderz: B6->B8 with miai of eyes W7, W6 is equivalent.
This is the local seki -> center group dead -> huge win. (in the game)

imaginary position (2)  

Ed?: This is the best I have found for white. White has a ko but needs two approach moves ( one at 'a' and one at 'b').

tderz: What if black does not play B1, but tenuki?

I have the feeling that black cannot improve his position now, by playing B1 (he cannot approach either) - a ko should be taken last.
White can use 3 moves to approach at a, e and b, Black had to take the the direct ko at B1 - and keep it that way (very dangerous).
Perhaps black could play B1 after the approach move a only.

But the position is clearly won if Black gives White no chance to make the ko real. So perhaps B1 is safest.

Just lost a tournament game involving a 2-3-stage ko which I did not take serious (but my game losing oversight was somewhere else).

Tsumego From Games 60 / Solutions3 last edited by Unkx80 on July 8, 2008 - 10:52
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