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The most difficult yose problem

https://www.lifein19x19.com/viewtopic.php?t=18589

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Re: The most difficult yose problem

Posted: Mon Feb 14, 2022 6:51 am
by Cassandra
Click Here To Show Diagram Code
[go]$$Wm72 Komi = 0.5; prisoners: :b21: :w8:
$$ +---------------------------+
$$ | . . O X X X X X O . O . O |
$$ | . 1 O O O O X X O . X . O |
$$ | . O X X O X X X O O O O O |
$$ | . O X O X X , . X X X X O |
$$ | . a Z O O X . X X X . X X |
$$ | . O X . O X . . . . . O . |
$$ | O O O O O X O O O X X X . |
$$ | X O X X O O X X O X O X X |
$$ | X X X . X O X X X X O O O |
$$ | . . X , X O O X X X O b X |
$$ | O O O X X O O O X X O X O |
$$ | . X O X O . X O X O O O . |
$$ | O X O X O O . O X X O . O |
$$ +---------------------------+[/go]
White will connect at :w72: in the upper left corner (instead of at A at the left edge), so erasing a Black ko-threat!
=> White +

:bx: is not really a genuine ko-threat!
Capturing at White B would also result in a White win!

Re: The most difficult yose problem

Posted: Mon Feb 14, 2022 7:15 am
by jmeinh
Cassandra wrote:
Click Here To Show Diagram Code
[go]$$Wm72 Komi = 0.5; prisoners: :b21: :w8:
$$ +---------------------------+
$$ | . . O X X X X X O . O . O |
$$ | . 1 O O O O X X O . X . O |
$$ | . O X X O X X X O O O O O |
$$ | . O X O X X , . X X X X O |
$$ | . a Z O O X . X X X . X X |
$$ | . O X . O X . . . . . O . |
$$ | O O O O O X O O O X X X . |
$$ | X O X X O O X X O X O X X |
$$ | X X X . X O X X X X O O O |
$$ | . . X , X O O X X X O b X |
$$ | O O O X X O O O X X O X O |
$$ | . X O X O . X O X O O O . |
$$ | O X O X O O . O X X O . O |
$$ +---------------------------+[/go]
White will connect at :w72: in the upper left corner (instead of at A at the left edge), so erasing a Black ko-threat!
=> White +

:bx: is not really a genuine ko-threat!
Capturing at White B would also result in a White win!
Yes, I agree. Then (if only because of the additional white ko-threats on K8 etc.) it is again Black who needs help...

Re: The most difficult yose problem

Posted: Mon Feb 14, 2022 8:02 am
by Gérard TAILLE
jmeinh wrote:
Cassandra wrote:
Click Here To Show Diagram Code
[go]$$Wm72 Komi = 0.5; prisoners: :b21: :w8:
$$ +---------------------------+
$$ | . . O X X X X X O . O . O |
$$ | . 1 O O O O X X O . X . O |
$$ | . O X X O X X X O O O O O |
$$ | . O X O X X , . X X X X O |
$$ | . a Z O O X . X X X . X X |
$$ | . O X . O X . . . . . O . |
$$ | O O O O O X O O O X X X . |
$$ | X O X X O O X X O X O X X |
$$ | X X X . X O X X X X O O O |
$$ | . . X , X O O X X X O b X |
$$ | O O O X X O O O X X O X O |
$$ | . X O X O . X O X O O O . |
$$ | O X O X O O . O X X O . O |
$$ +---------------------------+[/go]
White will connect at :w72: in the upper left corner (instead of at A at the left edge), so erasing a Black ko-threat!
=> White +

:bx: is not really a genuine ko-threat!
Capturing at White B would also result in a White win!
Yes, I agree. Then (if only because of the additional white ko-threats on K8 etc.) it is again Black who needs help...
Yes. What about this new one (119 moves):

Re: The most difficult yose problem

Posted: Mon Feb 14, 2022 8:16 am
by Cassandra
Gérard TAILLE wrote:Yes. What about this new one (119 moves):
It's the same issue as mentioned before.

Black's atari :b71: at White's six stones at the upper edge is NO genuine ko-threat.
=> White will capture the ko and win by 1.5 points (it results a change in the order of moves with the older line, where Black created a five-stone string).

Re: The most difficult yose problem

Posted: Mon Feb 14, 2022 8:39 am
by Gérard TAILLE
Cassandra wrote:
Gérard TAILLE wrote:Yes. What about this new one (119 moves):
It's the same issue as mentioned before.

Black's atari :b71: at White's six stones at the upper edge is NO genuine ko-threat.
=> White will capture the ko and win by 1.5 points (it results a change in the order of moves with the older line, where Black created a five-stone string).
Yes. At least the number of ideas increases but we have still to find this very long sequence.

Re: The most difficult yose problem

Posted: Mon Feb 14, 2022 9:08 am
by Cassandra
Gérard TAILLE wrote:At least the number of ideas increases but we have still to find this very long sequence.
I have not checked this yet (and so do not have any idea whether the hint might be useful / succesful applicable):

Have you ever tried your idea (seems reasonable in principle) at the other stage of the ko-fight in the lower right corner?

Re: The most difficult yose problem

Posted: Mon Feb 14, 2022 10:34 am
by dany
Gérard TAILLE wrote:Yes. What about this new one (119 moves):
almost the solution, but the order of ko threats matters

Re: The most difficult yose problem

Posted: Mon Feb 14, 2022 10:46 am
by Gérard TAILLE
dany wrote:
Gérard TAILLE wrote:Yes. What about this new one (119 moves):
almost the solution, but the order of ko threats matters
Here is a new attempt with 113 moves and a black win by 0.5 points:

Re: The most difficult yose problem

Posted: Mon Feb 14, 2022 10:51 am
by Cassandra
dany wrote:
Gérard TAILLE wrote:Yes. What about this new one (119 moves):
almost the solution, but the order of ko threats matters
At least one correct "feeling" in the last stage of the solution finding ...
:razz:

However, I still don't like the large number of White pass-"moves" in this problem.
Taken together with the large difference in the number of Black and White stones in the starting position, this gives an "unbalanced" impression.

Re: The most difficult yose problem

Posted: Mon Feb 14, 2022 11:01 am
by jmeinh
Gérard TAILLE wrote:Yes. What about this new one (119 moves):
If White captures the bottom right stones with move 88, S must capture the top right corner with 2 moves and it ends again with W+0.5 .

Re: The most difficult yose problem

Posted: Mon Feb 14, 2022 11:15 am
by Cassandra
jmeinh wrote:
Gérard TAILLE wrote:Yes. What about this new one (119 moves):
If White captures the bottom right stones with move 88, S must capture the top right corner with 2 moves and it ends again with W+0.5 .
Black only needs to invest ONE stone in the top right, because it is enough to capture the single White stone there.
=> Black + 0.5.

______________________
You really meant the 113-move solution attempt, didn't you?

Re: The most difficult yose problem

Posted: Mon Feb 14, 2022 11:45 am
by Gérard TAILLE
jmeinh wrote:
Gérard TAILLE wrote:Yes. What about this new one (119 moves):
If White captures the bottom right stones with move 88, S must capture the top right corner with 2 moves and it ends again with W+0.5 .
I hope the last adjustement:

Re: The most difficult yose problem

Posted: Mon Feb 14, 2022 11:50 am
by dany
Gérard TAILLE wrote:Here is a new attempt with 113 moves and a black win by 0.5 points:
Not yet
Click Here To Show Diagram Code
[go]$$Wm88
$$ +---------------------------+
$$ | . . O X X X X X O X O . O |
$$ | . . O O O O X X O . X O O |
$$ | . O X X O X X X O O O O O |
$$ | . O X O X X , . X X X X O |
$$ | . . . O O X . X X X . X X |
$$ | . O X . O X . . X . X O . |
$$ | O O O O O X O O O X X X O |
$$ | X O X X O O X X O X O X X |
$$ | X X X . X O X X X X O O O |
$$ | . . X X X O O X X X O 1 . |
$$ | O O O X X O O O X X O . O |
$$ | . X O X O O . O X O O O . |
$$ | O X O X O O . O X X O . O |
$$ +---------------------------+[/go]
W+0.5

Re: The most difficult yose problem

Posted: Mon Feb 14, 2022 1:03 pm
by jmeinh
Gérard TAILLE wrote:
jmeinh wrote:
Gérard TAILLE wrote:Yes. What about this new one (119 moves):
If White captures the bottom right stones with move 88, S must capture the top right corner with 2 moves and it ends again with W+0.5 .
I hope the last adjustement:

This looks promising! May we already congratulate you? What does Dany say?

Re: The most difficult yose problem

Posted: Mon Feb 14, 2022 1:19 pm
by dany
jmeinh wrote:
Gérard TAILLE wrote:
I hope the last adjustement:

This looks promising! May we already congratulate you? What does Dany say?
Not yet
Click Here To Show Diagram Code
[go]$$Bm87
$$ +---------------------------+
$$ | . . O X X X X X O . O . O |
$$ | . . O O O O X X O O . O O |
$$ | . O X X O X X X O O O O O |
$$ | . O X O X X , . X X X X O |
$$ | . . . O O X . X X X . X X |
$$ | . O X . O X . . X . X O . |
$$ | O O O O O X O O O X X X O |
$$ | X O X X O O X X O X O X X |
$$ | X X X . X O X X X X O O O |
$$ | . . X X X O O X X X O 2 X |
$$ | O O O X X O O O X X O X O |
$$ | . X O X O 3 X O X O O O . |
$$ | O X O X O O 1 O X X O . O |
$$ +---------------------------+[/go]
W+0.5

crazy ko mechanics ;-)
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