I am as puzzled as Gérard is about all of this.
So Gérard posted this diagram:
I've copied the resulting shape below. It is clear to me that white needs to win the ko at 'a' in order to live. There is no double ko here. Whether black has local threats or not shouldn't matter, should it?
The only difference I see between this tsumego and other tsumego that are commonly accepted to end in "life / death by ko" is that the ko at 'a' is already present at the beginning of the tsumego.
Shikatsu Myoki Tsumego Series
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jlt
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Re: Shikatsu Myoki Tsumego Series
That position is possible becauseFarodin wrote: I've copied the resulting shape below. It is clear to me that white needs to win the ko at 'a' in order to live. There is no double ko here. Whether black has local threats or not shouldn't matter, should it?
played a ko threat elsewhere, and 
responded. Whether you accept - is a matter of convention.-
Kirby
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Re: Shikatsu Myoki Tsumego Series
White is alive in double ko. I really don't understand the objection to this.
be immersed
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Gérard TAILLE
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Re: Shikatsu Myoki Tsumego Series
Consider at the beginning that black is only interested by winning the ko at "a". It is white to play but for black b and c are miai, that is the point.Kirby wrote:White is alive in double ko. I really don't understand the objection to this.
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Re: Shikatsu Myoki Tsumego Series
I get your point - black insists on the ko at 'a'.
Then, I agree with you. I think it's ko.
Then, I agree with you. I think it's ko.
be immersed
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Farodin
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Re: Shikatsu Myoki Tsumego Series
Thank you, I didn't see the nose attach at 5. So now I can agree that it is alive in double koShaddy wrote:
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Gérard TAILLE
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Re: Shikatsu Myoki Tsumego Series
Fine Shaddy, as Farodin, I didn't see the nose attach at 5.Shaddy wrote:
That prove that my move
was not correct, allowing you to take at 
in good conditions.Far better seems:
Now I do not think you will play the sequence
which looks quite bad due to the awful previous exchange of the two marked stones.If the idea is to escape on the left then I think white should play
with a good result for white
Due to this variant I think black
may be a mistake and I prefer simply taking the corner with ko by:
In any case thank you for your help Shaddy, I appreciate.-
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Re: Shikatsu Myoki Tsumego Series
It is irrelevant, whether is at a or at b alternatively.
ko threat
elsewhere
White lives in double-ko.
is at a or at b alternatively. ko threat elsewhereWhite lives in double-ko.
The really most difficult Go problem ever: https://igohatsuyoron120.de/index.htm
Igo Hatsuyōron #120 (really solved by KataGo)
Igo Hatsuyōron #120 (really solved by KataGo)
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Gérard TAILLE
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Re: Shikatsu Myoki Tsumego Series
My proposal was to play to continue fighting the ko on the right till a black connection.Cassandra wrote: It is irrelevant, whether
White lives in double-ko.
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Re: Shikatsu Myoki Tsumego Series
Wow, this position is more interesting than I thought. If black plays like that, can white just do this?Gérard TAILLE wrote:Shaddy wrote:
Due to this variant I think black
Then if black plays at 'a', there's another double ko at 'b' and 'c'.
be immersed
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Re: Shikatsu Myoki Tsumego Series
Fancy that! A discussion on L19. Maybe I should buy a lottery ticket this week....
Just a small corrective: in the original this is problem 65, not 76, it is not marked as a 'to live' (or ko) problem, nowhere is it described as 'unconditional' life (it says "lives with double ko"), and the categories given in SL do not exist.
Furthermore, the title and the introductory text, as well as conventions, guide us to the double ko solution. In particular, the introduction tells us that the collection is a mixture of old and new problems. The main characteristic of old problems is that they show us the myoki (wonderful wizardry) in the solutions. The problems were objets d'art, intended for discussion (exactly as we have here). The "solution" was to find the beauty, the wizardry, the talking point. A mini-algorithm approach might give an easier (and uglier) solution, but that is to miss the point.
Although this enlightened and enlightening way of viewing problems was essentially a Chinese one, and was underpinned by names for problems that either led to spotting a fancy solution or that gave food for thought in the discussion, the Japanese encapsulated the implied conventions in the term tsumego. A tsumego is a compressed or miniaturised go position. The rest of the board (or the state of play) doesn't matter. That convention also applies to "new" problems. A problem is a problem, not a mini-game. The derived conventions (such as ladders work, ko threats elsewhere are irrelevant) are well known but are sometimes still spelled out in books and magazines. This is not least because tsumego problems have often been used as prize competitions and so competition rules have to be clearly stated. Shikatsu Myoki was the result of precisely such a prize competition series in a newspaper.
So, while finding new wrinkles, as here, is commendable, it does not mean that the original problem was in any way wrong or flawed (although, of course, some old problems have been found to be flawed, most often because of missing or misplaced stones, probably due to editorial interventions, or carvos).
Just a small corrective: in the original this is problem 65, not 76, it is not marked as a 'to live' (or ko) problem, nowhere is it described as 'unconditional' life (it says "lives with double ko"), and the categories given in SL do not exist.
Furthermore, the title and the introductory text, as well as conventions, guide us to the double ko solution. In particular, the introduction tells us that the collection is a mixture of old and new problems. The main characteristic of old problems is that they show us the myoki (wonderful wizardry) in the solutions. The problems were objets d'art, intended for discussion (exactly as we have here). The "solution" was to find the beauty, the wizardry, the talking point. A mini-algorithm approach might give an easier (and uglier) solution, but that is to miss the point.
Although this enlightened and enlightening way of viewing problems was essentially a Chinese one, and was underpinned by names for problems that either led to spotting a fancy solution or that gave food for thought in the discussion, the Japanese encapsulated the implied conventions in the term tsumego. A tsumego is a compressed or miniaturised go position. The rest of the board (or the state of play) doesn't matter. That convention also applies to "new" problems. A problem is a problem, not a mini-game. The derived conventions (such as ladders work, ko threats elsewhere are irrelevant) are well known but are sometimes still spelled out in books and magazines. This is not least because tsumego problems have often been used as prize competitions and so competition rules have to be clearly stated. Shikatsu Myoki was the result of precisely such a prize competition series in a newspaper.
So, while finding new wrinkles, as here, is commendable, it does not mean that the original problem was in any way wrong or flawed (although, of course, some old problems have been found to be flawed, most often because of missing or misplaced stones, probably due to editorial interventions, or carvos).
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Re: Shikatsu Myoki Tsumego Series
Yes Kirby the black position seems not quite good. I agree with you.Kirby wrote:Wow, this position is more interesting than I thought. If black plays like that, can white just do this?Gérard TAILLE wrote:Shaddy wrote:
Due to this variant I think black
Then if black plays at 'a', there's another double ko at 'b' and 'c'.
Where are we?
The solution given is the following: white is living by double ko and we may (?) assume later the exchange
Looking at all this sequence it seems to me the exchange
is not good for white.So my first question is the following
Isn't it better for white to take immediatly the ko on the left by
here above? What is the best answer for black?Second question: seeing the result above isn't it better for black to play simply the sente yose by
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Re: Shikatsu Myoki Tsumego Series
https://senseis.xmp.net/?ShikatsuMyokiTsumegoSeries156
It is said that the following sequence is a failure for white: and black has managed to get a ko.
It is true OC.
is probably a wrong move but the moves 
and 
seem also wrong.
Beginning with the white move I believe white can win the race without any condition by playing at "a" or "b". Do you agree?
It is said that the following sequence is a failure for white: and black has managed to get a ko.
It is true OC.
is probably a wrong move but the moves and seem also wrong.Beginning with the white move
I believe white can win the race without any condition by playing at "a" or "b". Do you agree?-
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Re: Shikatsu Myoki Tsumego Series
Note added to the SL Solution page. The confusion seems to be caused by a difference in problem conventions, old and new.