TsumegoFromGames64/Attempts

Sub-page of TsumegoFromGames64
[Diagram]
Attempt. Moves 1-10  

Herman Hiddema: Hmmm, looks bad for white. Here's an attempt which results in ko...

[Diagram]
Attempt, moves 11-20  

Herman Hiddema: [90] Black can also take the ko with B3. White can then play W4 as a ko threat, and after B5 white retakes the ko and we get basically the same result.

[Diagram]
Zinger's idea  

zinger: [100] Egads, black is risking a lot by doing this! If I were black, I would just play B3 at W4 in the first diagram, then work on the center with a - it looks like enough to win. Sorry for giving a counting reply to a tsumego problem, but after all, the whole board was posted :)

[Diagram]
Zinger's idea  

[110] tderz the left side is now worth

  • lower white group: 14 white stones + 13 territory = 41
  • separating black stones: 11B + 2T = 24
  • upper white group: 9W + 10T = 28
    • the sum is 41 + 24 + 28 = 93 points, which is substantially bigger than the meagre centre of 12-16 points.

This variation is not playable with B5! (B5 instead of a)

[Diagram]
Zinger's idea  

[120] tderz: better immediately the ko, as White could not connect with W6, she would be lost. However, this ko is so big, that only internal ko threats could be valid?

[Diagram]
Zinger's idea  

[130] tderz: perhaps something like this (if now m or c, then something like n)
and living with the lower group, or simply c as threat.

[Diagram]
Zinger's idea?  

Chris Hayashida: I got the idea that this was the sequence that Zinger suggested. While he did mark a on the second diagram, I think he was referring B3 and W4 on the first diagram.

I'm not sure that this would be enough for Black. a, b, and c are all big points, and White has sente. When I was playing, I counted that White was ahead if his group survived. I probably need to re-evaluate this position to see if this is still the case.

zinger: Yes, this is what I meant. I count black ahead by about 10 points on the board, but then there's komi, and it's white's turn. So maybe it's about even. Still, I would do this rather than risk everything, and rely on my endgame. Besides, it looks like white lives anyway. Chris: did you win in the end? By how much?


My solution

Chris Hayashida: This is what I played during the tournament. I don't want to list it as a solution until it stands up against scrutiny from the other deshi. If it does, I'll move it to the solution subpage.

[Diagram]
Game  

Chris Hayashida: [10] This took me five minutes to read out (during the tournament) and I finally played this sequence. It is a similar sequence to what was posted above, but I played atari with W6 and saved the other moves for local ko threats.

[Diagram]
Variation 1  

Chris Hayashida: [20] If B1, then White throws in at W2 and catches the marked black stones in oiotoshi for a second eye. This is what happened in the game.

[Diagram]
Variation 2 - Ko  

Chris Hayashida: [30] This was the variation that I wasn't as sure about. B1 leads to ko, but I think White has a huge number of local threats, starting with W2.

[Diagram]
Variation 2 - Ko  

tderz: [32] a and b are miai - hence White cannot live without ko and must exploit (internal) ko threats c, d, else or in combination.

[Diagram]
Black resolves the ko  

Chris Hayashida: [40] If Black plays B1 to resolve the ko, then W2 again catches the marked black stones in oiotoshi for the second eye.

[Diagram]
Variation 2 - Ko resolving  

tderz: [42] Above B1 (over)kills a dead white group. White lives, hence Black did not achieve much else than putting stones in his own territory.

[Diagram]

White resolves the ko


TsumegoFromGames64/Attempts last edited by 50.23.115.116 on January 27, 2015 - 05:46
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