Problem Nr. 344 from Cho's intermediate Problems
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Nagilum
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Problem Nr. 344 from Cho's intermediate Problems
Hi,
this is Problem Nr. 344 from Cho's intermediate Problems. http://tsumego.tasuki.org/?page=tsumego
i can't find the solution. Not even a ko. Any Suggestions?
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HermanHiddema
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Nagilum
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Re: Problem Nr. 344 from Cho's intermediate Problems
Wow. Thanks for the answer. 
Good to know that this game can still surprise me.
I really thought that there is no answer for this problem. (Indeed, this seems to be true under a ruleset with super-ko.)
IMO, not really an standard problem.
Good to know that this game can still surprise me.
I really thought that there is no answer for this problem. (Indeed, this seems to be true under a ruleset with super-ko.)
IMO, not really an standard problem.
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ez4u
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Re: Problem Nr. 344 from Cho's intermediate Problems
This is Cho Chikun's collection, so I think it is reasonable to assume you are using Japanese rules. Besides, if you can read out to this point, you have achieved the pedagogical objective.
Dave Sigaty
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"Short-lived are both the praiser and the praised, and rememberer and the remembered..."
- Marcus Aurelius; Meditations, VIII 21
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Solomon
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Re: Problem Nr. 344 from Cho's intermediate Problems
A good exercise is to consider this move as well, which doesn't lead to eternal life but still gives a satisfactory result for Black if he plays correctly:
Re: Problem Nr. 344 from Cho's intermediate Problems
Be sure to remember that when a similar position arises in your AGA tournament games this weekend, that Black dies. The American Go Association rules have situational superko, which prohibits Black from repeating the position that Black 7 creates in HermanHiddema's diagram above.
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jts
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Re: Problem Nr. 344 from Cho's intermediate Problems
gonut wrote:Be sure to remember that when a similar position arises in your AGA tournament games this weekend, that Black dies. The American Go Association rules have situational superko, which prohibits Black from repeating the position that Black 7 creates in HermanHiddema's diagram above.
Even after making a ko threat?
Here is a problem which stumped me:
(Doubly embarrassing because either I got it right the first three times and I have since lost the ability to solve it, or I thought I had solved it three times and didn't see a really obvious problem with my "solution".)
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entropi
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Re: Problem Nr. 344 from Cho's intermediate Problems
I still didn't have my morning coffee, so forgive me if I overlook something obvious. But I don't see why black c5 doesn't lead to a ko.
If you say no, Elwood and I will come here for breakfast, lunch, and dinner every day of the week.
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perceval
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Re: Problem Nr. 344 from Cho's intermediate Problems
at A19? (and the under the stone 
In theory, there is no difference between theory and practice. In practice, there is.
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entropi
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Re: Problem Nr. 344 from Cho's intermediate Problems
jts wrote:gonut wrote:Be sure to remember that when a similar position arises in your AGA tournament games this weekend, that Black dies. The American Go Association rules have situational superko, which prohibits Black from repeating the position that Black 7 creates in HermanHiddema's diagram above.
Even after making a ko threat?
As soon as black plays 7 white can play 8 again leading to the same local situation. Then black is again obliged to play c6, white captures at e6 and then black needs to find another ko threat. Sooner or later black will run out of ko threats while white doesn't need to play any threat.
If you say no, Elwood and I will come here for breakfast, lunch, and dinner every day of the week.
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entropi
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Re: Problem Nr. 344 from Cho's intermediate Problems
?If you say no, Elwood and I will come here for breakfast, lunch, and dinner every day of the week.
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HermanHiddema
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Re: Problem Nr. 344 from Cho's intermediate Problems
entropi wrote:I still didn't have my morning coffee, so forgive me if I overlook something obvious. But I don't see why black c5 doesn't lead to a ko.
After the sequence shown, black dies in double ko:
Because of the two kos labeled a, the marked stone can never be captured. Note that black may take the corner stone, but it doesn't give him an eye.
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jts
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Re: Problem Nr. 344 from Cho's intermediate Problems
entropi wrote:jts wrote:gonut wrote:Be sure to remember that when a similar position arises in your AGA tournament games this weekend, that Black dies. The American Go Association rules have situational superko, which prohibits Black from repeating the position that Black 7 creates in HermanHiddema's diagram above.
Even after making a ko threat?
As soon as black plays 7 white can play 8 again leading to the same local situation. Then black is again obliged to play c6, white captures at e6 and then black needs to find another ko threat. Sooner or later black will run out of ko threats while white doesn't need to play any threat.
Ah, ok. So under situational superko, this functions in the same way as a double ko - unwinnable by black, but an infinite source of 30 pt. ko threats?
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HermanHiddema
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Re: Problem Nr. 344 from Cho's intermediate Problems
jts wrote:entropi wrote:jts wrote:Even after making a ko threat?
As soon as black plays 7 white can play 8 again leading to the same local situation. Then black is again obliged to play c6, white captures at e6 and then black needs to find another ko threat. Sooner or later black will run out of ko threats while white doesn't need to play any threat.
Ah, ok. So under situational superko, this functions in the same way as a double ko - unwinnable by black, but an infinite source of 30 pt. ko threats?
No, actually you can play it as a regular ko, but it is a little more tricky to remember which positions have already occurred.
There are four positions in the cycle:
In the last one, if black captures, it returns to the first one.
Now lets examine how ko is played here. In the example from the problem, position 1 is the first to arise, after
That means, that after playing through positions 2,3 and 4, black cannot return to position 1.
So Black makes a ko threat, and White responds.
Now, we are still at position 4, but two new stones elsewhere have been played. So position 4 is the first one that cannot be repeated from here.
Black captures (goes to position 1), white throws in (position 2), black pushes in (position 3).
At this point, white is not allowed to capture, as that would return to the position we had after the ko threat and response had been played (position 4).
So White plays a ko threat, and Black responds.
We are then at position 3, which is now the first one that cannot be repeated.
Move through positions 4, 1 and 2 (W, B, W) and it is Black who needs a threat.
Etcetera.