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The most difficult yose problem
Posted: Sun Jan 30, 2022 1:05 pm
by dany
Masterpiece created by Cho U 9 dan
$$c Black to play, komi 0.5
$$ +---------------------------+
$$ | . . O X X X X . O . X X . |
$$ | . . O O O . . . O . . . . |
$$ | . . . . O X X X O O O O . |
$$ | . . . O . X , . . X X X . |
$$ | . . . O O X . X X X . X X |
$$ | . O X . O X . . . . . O . |
$$ | O O O O O X , . O X X X . |
$$ | X O X X O . X . . X O X X |
$$ | X X X . X O X . . X O O O |
$$ | . . X , . O , X X X O . . |
$$ | O . . X X O O O X X O . . |
$$ | X . O . O . X O X O O . . |
$$ | . X O X . O . . X X O . . |
$$ +---------------------------+
- Click Here To Show Diagram Code
[go]$$c Black to play, komi 0.5
$$ +---------------------------+
$$ | . . O X X X X . O . X X . |
$$ | . . O O O . . . O . . . . |
$$ | . . . . O X X X O O O O . |
$$ | . . . O . X , . . X X X . |
$$ | . . . O O X . X X X . X X |
$$ | . O X . O X . . . . . O . |
$$ | O O O O O X , . O X X X . |
$$ | X O X X O . X . . X O X X |
$$ | X X X . X O X . . X O O O |
$$ | . . X , . O , X X X O . . |
$$ | O . . X X O O O X X O . . |
$$ | X . O . O . X O X O O . . |
$$ | . X O X . O . . X X O . . |
$$ +---------------------------+[/go]
Re: The most difficult yose problem
Posted: Sun Jan 30, 2022 1:14 pm
by lichigo
Wouah indeed really hard. Where did you find this problem?
Re: The most difficult yose problem
Posted: Tue Feb 08, 2022 7:53 am
by dany
Several years ago, in his lecture, Alexander Dinerstein 3p talked about solving this problem.
But imho not all the important moves were explained in his lecture, and some were wrong
Will someone try to find a solution?
Re: The most difficult yose problem
Posted: Tue Feb 08, 2022 10:01 am
by kvasir
That is good example of the maxim that yose is also a life and death problem.
Re: The most difficult yose problem
Posted: Wed Feb 09, 2022 4:05 am
by Gérard TAILLE
dany wrote:Several years ago, in his lecture, Alexander Dinerstein 3p talked about solving this problem.
But imho not all the important moves were explained in his lecture, and some were wrong
Will someone try to find a solution?
This problem is quite difficult but I can try to find something.
Just a confirmation : seeing 53 black stones against 45 white stones is it a good understanding that japanese rules are used for this problem?
Re: The most difficult yose problem
Posted: Wed Feb 09, 2022 5:56 am
by dany
Gérard TAILLE wrote:
This problem is quite difficult but I can try to find something.
Just a confirmation : seeing 53 black stones against 45 white stones is it a good understanding that japanese rules are used for this problem?
Yes, Japanese rules, komi 0.5
Re: The most difficult yose problem
Posted: Thu Feb 10, 2022 3:17 am
by Cassandra
Let's start ...
$$ Komi = 0.5; no prisoners
$$ +---------------------------+
$$ | . . O X X X X . O . X X . |
$$ | . . O O O . . . O . . . . |
$$ | . . . . O X X X O O O O . |
$$ | . . . O . X , . . X X X . |
$$ | . . . O O X . X X X . X X |
$$ | . O X . O X . . . . . O . |
$$ | O O O O O X , . O X X X . |
$$ | X O X X O . X . . X O X X |
$$ | X X X . X O X . . X O O O |
$$ | . . X , . O , X X X O . . |
$$ | O . . X X O O O X X O . . |
$$ | X . O 1 O . X O X O O . . |
$$ | . X O X . O . . X X O . . |
$$ +---------------------------+
- Click Here To Show Diagram Code
[go]$$ Komi = 0.5; no prisoners
$$ +---------------------------+
$$ | . . O X X X X . O . X X . |
$$ | . . O O O . . . O . . . . |
$$ | . . . . O X X X O O O O . |
$$ | . . . O . X , . . X X X . |
$$ | . . . O O X . X X X . X X |
$$ | . O X . O X . . . . . O . |
$$ | O O O O O X , . O X X X . |
$$ | X O X X O . X . . X O X X |
$$ | X X X . X O X . . X O O O |
$$ | . . X , . O , X X X O . . |
$$ | O . . X X O O O X X O . . |
$$ | X . O 1 O . X O X O O . . |
$$ | . X O X . O . . X X O . . |
$$ +---------------------------+[/go]
Re: The most difficult yose problem
Posted: Thu Feb 10, 2022 7:21 am
by Harleqin
Yes, seems so, and then
$$ Komi = 0.5; no prisoners
$$ +---------------------------+
$$ | . . O X X X X . O . X X . |
$$ | . . O O O . . . O . . . . |
$$ | . . . . O X X X O O O O . |
$$ | . . . O . X , . . X X X . |
$$ | . . . O O X . X X X . X X |
$$ | . O X . O X . . . . . O . |
$$ | O O O O O X , . O X X X . |
$$ | X O X X O . X . . X O X X |
$$ | X X X a X O X . . X O O O |
$$ | . . X b 2 O , X X X O . . |
$$ | O . . X X O O O X X O . . |
$$ | X . O 1 O . X O X O O . . |
$$ | . X O X . O . . X X O . . |
$$ +---------------------------+
- Click Here To Show Diagram Code
[go]$$ Komi = 0.5; no prisoners
$$ +---------------------------+
$$ | . . O X X X X . O . X X . |
$$ | . . O O O . . . O . . . . |
$$ | . . . . O X X X O O O O . |
$$ | . . . O . X , . . X X X . |
$$ | . . . O O X . X X X . X X |
$$ | . O X . O X . . . . . O . |
$$ | O O O O O X , . O X X X . |
$$ | X O X X O . X . . X O X X |
$$ | X X X a X O X . . X O O O |
$$ | . . X b 2 O , X X X O . . |
$$ | O . . X X O O O X X O . . |
$$ | X . O 1 O . X O X O O . . |
$$ | . X O X . O . . X X O . . |
$$ +---------------------------+[/go]
Then 'a' or 'b'? What's that funny shape in the corner?
Re: The most difficult yose problem
Posted: Thu Feb 10, 2022 8:05 am
by Cassandra
Harleqin wrote:What's that funny shape in the corner?
Probably aiming at a fight for creating a seki in the corner???
$$ Komi = 0.5; no prisoners
$$ +---------------------------+
$$ | . . O X X X X . O . X X . |
$$ | . . O O O . . . O . . . . |
$$ | . . . . O X X X O O O O . |
$$ | . . . O . X , . . X X X . |
$$ | . . . O O X . X X X . X X |
$$ | . O X . O X . . . . . O . |
$$ | O O O O O X , . O X X X . |
$$ | X O X X O . X . . X O X X |
$$ | X X X . X O X . . X O O O |
$$ | . . X . . O , X X X O . . |
$$ | O 2 . X X O O O X X O . . |
$$ | X . O X O . X O X O O . . |
$$ | . X O X . O . . X X O . . |
$$ +---------------------------+
- Click Here To Show Diagram Code
[go]$$ Komi = 0.5; no prisoners
$$ +---------------------------+
$$ | . . O X X X X . O . X X . |
$$ | . . O O O . . . O . . . . |
$$ | . . . . O X X X O O O O . |
$$ | . . . O . X , . . X X X . |
$$ | . . . O O X . X X X . X X |
$$ | . O X . O X . . . . . O . |
$$ | O O O O O X , . O X X X . |
$$ | X O X X O . X . . X O X X |
$$ | X X X . X O X . . X O O O |
$$ | . . X . . O , X X X O . . |
$$ | O 2 . X X O O O X X O . . |
$$ | X . O X O . X O X O O . . |
$$ | . X O X . O . . X X O . . |
$$ +---------------------------+[/go]
Re: The most difficult yose problem
Posted: Thu Feb 10, 2022 11:31 am
by Gérard TAILLE
Harleqin wrote:Yes, seems so, and then
$$ Komi = 0.5; no prisoners
$$ +---------------------------+
$$ | . . O X X X X . O . X X . |
$$ | . . O O O . . . O . . . . |
$$ | . . . . O X X X O O O O . |
$$ | . . . O . X , . . X X X . |
$$ | . . . O O X . X X X . X X |
$$ | . O X . O X . . . . . O . |
$$ | O O O O O X , . O X X X . |
$$ | X O X X O . X . . X O X X |
$$ | X X X a X O X . . X O O O |
$$ | . . X b 2 O , X X X O . . |
$$ | O . . X X O O O X X O . . |
$$ | X . O 1 O . X O X O O . . |
$$ | . X O X . O . . X X O . . |
$$ +---------------------------+
- Click Here To Show Diagram Code
[go]$$ Komi = 0.5; no prisoners
$$ +---------------------------+
$$ | . . O X X X X . O . X X . |
$$ | . . O O O . . . O . . . . |
$$ | . . . . O X X X O O O O . |
$$ | . . . O . X , . . X X X . |
$$ | . . . O O X . X X X . X X |
$$ | . O X . O X . . . . . O . |
$$ | O O O O O X , . O X X X . |
$$ | X O X X O . X . . X O X X |
$$ | X X X a X O X . . X O O O |
$$ | . . X b 2 O , X X X O . . |
$$ | O . . X X O O O X X O . . |
$$ | X . O 1 O . X O X O O . . |
$$ | . X O X . O . . X X O . . |
$$ +---------------------------+[/go]
Then 'a' or 'b'? What's that funny shape in the corner?
As far as I am concerned I see a quite simple win for black for this yose. As a consequence I know for sure that I did not fond the good defense for white.
My best sequence begins with your suggestion Harleqin:
$$ Komi = 0.5; no prisoners
$$ +---------------------------+
$$ | . . O X X X X . O . X X . |
$$ | . . O O O . . . O . . . . |
$$ | . . . . O X X X O O O O . |
$$ | . . . O . X , . . X X X . |
$$ | . . . O O X . X X X . X X |
$$ | . O X . O X . . . . . O . |
$$ | O O O O O X , . O X X X . |
$$ | X O X X O 4 X . . X O X X |
$$ | X X X 3 X O X . . X O O O |
$$ | . . X . 2 O , X X X O . . |
$$ | O . . X X O O O X X O . . |
$$ | X 5 O 1 O . X O X O O . . |
$$ | . X O X . O . . X X O . . |
$$ +---------------------------+
- Click Here To Show Diagram Code
[go]$$ Komi = 0.5; no prisoners
$$ +---------------------------+
$$ | . . O X X X X . O . X X . |
$$ | . . O O O . . . O . . . . |
$$ | . . . . O X X X O O O O . |
$$ | . . . O . X , . . X X X . |
$$ | . . . O O X . X X X . X X |
$$ | . O X . O X . . . . . O . |
$$ | O O O O O X , . O X X X . |
$$ | X O X X O 4 X . . X O X X |
$$ | X X X 3 X O X . . X O O O |
$$ | . . X . 2 O , X X X O . . |
$$ | O . . X X O O O X X O . . |
$$ | X 5 O 1 O . X O X O O . . |
$$ | . X O X . O . . X X O . . |
$$ +---------------------------+[/go]
but now I failed to find an interesting move for white.
I tried:
$$
$$ +---------------------------+
$$ | . . O X X X X . O . X X . |
$$ | . . O O O . . . O . . . . |
$$ | . . . . O X X X O O O O 6 |
$$ | . . . O . X , . . X X X . |
$$ | . . . O O X . X X X . X X |
$$ | . O X . O X . . . . . O . |
$$ | O O O O O X , . O X X X . |
$$ | X O X X O O X . . X O X X |
$$ | X X X X X O X . . X O O O |
$$ | . . X . O O , X X X O . . |
$$ | O . . X X O O O X X O 7 . |
$$ | X X O X O . X O X O O 8 9 |
$$ | . X O X . O . . X X O . . |
$$ +---------------------------+
- Click Here To Show Diagram Code
[go]$$
$$ +---------------------------+
$$ | . . O X X X X . O . X X . |
$$ | . . O O O . . . O . . . . |
$$ | . . . . O X X X O O O O 6 |
$$ | . . . O . X , . . X X X . |
$$ | . . . O O X . X X X . X X |
$$ | . O X . O X . . . . . O . |
$$ | O O O O O X , . O X X X . |
$$ | X O X X O O X . . X O X X |
$$ | X X X X X O X . . X O O O |
$$ | . . X . O O , X X X O . . |
$$ | O . . X X O O O X X O 7 . |
$$ | X X O X O . X O X O O 8 9 |
$$ | . X O X . O . . X X O . . |
$$ +---------------------------+[/go]
but now I do not see how white can cause difficulties for black. Surely I missed a hidden move somewhere.
Re: The most difficult yose problem
Posted: Thu Feb 10, 2022 11:43 am
by Cassandra
Gérard TAILLE wrote:... I do not see how white can cause difficulties for black. Surely I missed a hidden move somewhere.
$$ Komi = 0.5; no prisoners
$$ +---------------------------+
$$ | . . O X X X X . O . X X . |
$$ | . . O O O . . . O . . . . |
$$ | . . . . O X X X O O O O . |
$$ | . . . O . X , . . X X X . |
$$ | . . . O O X . X X X . X X |
$$ | . O X . O X . . . . . O . |
$$ | O O O O O X , . O X X X . |
$$ | X O X X O ? X . . X O X X |
$$ | X X X X X O X . . X O O O |
$$ | . . X . O O , X X X O . . |
$$ | O 4 . X X O O O X X O . . |
$$ | X . O X O . X O X O O . . |
$$ | . X O X . O . . X X O . . |
$$ +---------------------------+
- Click Here To Show Diagram Code
[go]$$ Komi = 0.5; no prisoners
$$ +---------------------------+
$$ | . . O X X X X . O . X X . |
$$ | . . O O O . . . O . . . . |
$$ | . . . . O X X X O O O O . |
$$ | . . . O . X , . . X X X . |
$$ | . . . O O X . X X X . X X |
$$ | . O X . O X . . . . . O . |
$$ | O O O O O X , . O X X X . |
$$ | X O X X O ? X . . X O X X |
$$ | X X X X X O X . . X O O O |
$$ | . . X . O O , X X X O . . |
$$ | O 4 . X X O O O X X O . . |
$$ | X . O X O . X O X O O . . |
$$ | . X O X . O . . X X O . . |
$$ +---------------------------+[/go]
Here you are!
Re: The most difficult yose problem
Posted: Thu Feb 10, 2022 12:31 pm
by jmeinh
Cassandra wrote:Gérard TAILLE wrote:... I do not see how white can cause difficulties for black. Surely I missed a hidden move somewhere.
$$ Komi = 0.5; no prisoners
$$ +---------------------------+
$$ | . . O X X X X . O . X X . |
$$ | . . O O O . . . O . . . . |
$$ | . . . . O X X X O O O O . |
$$ | . . . O . X , . . X X X . |
$$ | . . . O O X . X X X . X X |
$$ | . O X . O X . . . . . O . |
$$ | O O O O O X , . O X X X . |
$$ | X O X X O ? X . . X O X X |
$$ | X X X X X O X . . X O O O |
$$ | . . X . O O , X X X O . . |
$$ | O 4 . X X O O O X X O . . |
$$ | X . O X O . X O X O O . . |
$$ | . X O X . O . . X X O . . |
$$ +---------------------------+
- Click Here To Show Diagram Code
[go]$$ Komi = 0.5; no prisoners
$$ +---------------------------+
$$ | . . O X X X X . O . X X . |
$$ | . . O O O . . . O . . . . |
$$ | . . . . O X X X O O O O . |
$$ | . . . O . X , . . X X X . |
$$ | . . . O O X . X X X . X X |
$$ | . O X . O X . . . . . O . |
$$ | O O O O O X , . O X X X . |
$$ | X O X X O ? X . . X O X X |
$$ | X X X X X O X . . X O O O |
$$ | . . X . O O , X X X O . . |
$$ | O 4 . X X O O O X X O . . |
$$ | X . O X O . X O X O O . . |
$$ | . X O X . O . . X X O . . |
$$ +---------------------------+[/go]
Here you are!
Then maybe after...
$$ Komi = 0.5; no prisoners
$$ +---------------------------+
$$ | . . O X X X X . O . X X . |
$$ | . . O O O . . . O . . . . |
$$ | . . . . O X X X O O O O . |
$$ | . . . O . X , . . X X X . |
$$ | . . . O O X . X X X . X X |
$$ | . O X . O X . . . . . O . |
$$ | O O O O O X , . O X X X . |
$$ | X O X X O 5 X . . X O X X |
$$ | X X X X X O X . . X O O O |
$$ | . . X 7 O O . X X X O . . |
$$ | O O 6 X X O O O X X O . . |
$$ | X . O X O . X O X O O . . |
$$ | . X O X . O 8 . X X O . . |
$$ +---------------------------+
- Click Here To Show Diagram Code
[go]$$ Komi = 0.5; no prisoners
$$ +---------------------------+
$$ | . . O X X X X . O . X X . |
$$ | . . O O O . . . O . . . . |
$$ | . . . . O X X X O O O O . |
$$ | . . . O . X , . . X X X . |
$$ | . . . O O X . X X X . X X |
$$ | . O X . O X . . . . . O . |
$$ | O O O O O X , . O X X X . |
$$ | X O X X O 5 X . . X O X X |
$$ | X X X X X O X . . X O O O |
$$ | . . X 7 O O . X X X O . . |
$$ | O O 6 X X O O O X X O . . |
$$ | X . O X O . X O X O O . . |
$$ | . X O X . O 8 . X X O . . |
$$ +---------------------------+[/go]
$$ Komi = 0.5; no prisoners
$$ +---------------------------+
$$ | . . O X X X X . O . X X . |
$$ | . . O O O . . . O . . . . |
$$ | . . . . O X X X O O O O . |
$$ | . . . O . X , . . X X X . |
$$ | . . . O O X . X X X . X X |
$$ | . O X . O X . . . . . O . |
$$ | O O O O O X , . O X X X . |
$$ | X O X X O X X . . X O X X |
$$ | X X X X X O X . . X O O O |
$$ | 2 . X X O O 3 X X X O . . |
$$ | O O O X X O O O X X O . . |
$$ | X . O X O 4 X O X O O . . |
$$ | . X O X . O O 1 X X O . . |
$$ +---------------------------+
- Click Here To Show Diagram Code
[go]$$ Komi = 0.5; no prisoners
$$ +---------------------------+
$$ | . . O X X X X . O . X X . |
$$ | . . O O O . . . O . . . . |
$$ | . . . . O X X X O O O O . |
$$ | . . . O . X , . . X X X . |
$$ | . . . O O X . X X X . X X |
$$ | . O X . O X . . . . . O . |
$$ | O O O O O X , . O X X X . |
$$ | X O X X O X X . . X O X X |
$$ | X X X X X O X . . X O O O |
$$ | 2 . X X O O 3 X X X O . . |
$$ | O O O X X O O O X X O . . |
$$ | X . O X O 4 X O X O O . . |
$$ | . X O X . O O 1 X X O . . |
$$ +---------------------------+[/go]
... we have a first (temporary?) seki.
Re: The most difficult yose problem
Posted: Thu Feb 10, 2022 2:11 pm
by Cassandra
jmeinh wrote:... we have a first (temporary?) seki.
Yes, indeed.
But ...
$$ Komi = 0.5; no prisoners
$$ +---------------------------+
$$ | . . O X X X X . O . X X . |
$$ | . . O O O . . . O . . . . |
$$ | . . . . O X X X O O O O . |
$$ | . . . O . X , . . X X X . |
$$ | . . . O O X . X X X . X X |
$$ | . O X . O X . . . . . O . |
$$ | O O O O O X , . O X X X . |
$$ | X O X X O . X . . X O X X |
$$ | X X X 3 X O X . . X O O O |
$$ | . . X . O O , X X X O . . |
$$ | O . . X X O O O X X O . . |
$$ | X . O X O . X O X O O . . |
$$ | . X O X . O . . X X O . . |
$$ +---------------------------+
- Click Here To Show Diagram Code
[go]$$ Komi = 0.5; no prisoners
$$ +---------------------------+
$$ | . . O X X X X . O . X X . |
$$ | . . O O O . . . O . . . . |
$$ | . . . . O X X X O O O O . |
$$ | . . . O . X , . . X X X . |
$$ | . . . O O X . X X X . X X |
$$ | . O X . O X . . . . . O . |
$$ | O O O O O X , . O X X X . |
$$ | X O X X O . X . . X O X X |
$$ | X X X 3 X O X . . X O O O |
$$ | . . X . O O , X X X O . . |
$$ | O . . X X O O O X X O . . |
$$ | X . O X O . X O X O O . . |
$$ | . X O X . O . . X X O . . |
$$ +---------------------------+[/go]
...
is a mistake, ...
$$ Komi = 0.5; no prisoners
$$ +---------------------------+
$$ | . . O X X X X . O . X X . |
$$ | . . O O O . . . O . . . . |
$$ | . . . . O X X X O O O O . |
$$ | . . . O . X , . . X X X . |
$$ | . . . O O X . X X X . X X |
$$ | . O X . O X . . . . . O . |
$$ | O O O O O X , . O X X X . |
$$ | X O X X O . X . . X O X X |
$$ | X X X . X O X . . X O O O |
$$ | . . X . 2 O , X X X O . . |
$$ | O . . X X O O O X X O . . |
$$ | X . O X O . X O X O O . . |
$$ | . X O X . O . . X X O . . |
$$ +---------------------------+
- Click Here To Show Diagram Code
[go]$$ Komi = 0.5; no prisoners
$$ +---------------------------+
$$ | . . O X X X X . O . X X . |
$$ | . . O O O . . . O . . . . |
$$ | . . . . O X X X O O O O . |
$$ | . . . O . X , . . X X X . |
$$ | . . . O O X . X X X . X X |
$$ | . O X . O X . . . . . O . |
$$ | O O O O O X , . O X X X . |
$$ | X O X X O . X . . X O X X |
$$ | X X X . X O X . . X O O O |
$$ | . . X . 2 O , X X X O . . |
$$ | O . . X X O O O X X O . . |
$$ | X . O X O . X O X O O . . |
$$ | . X O X . O . . X X O . . |
$$ +---------------------------+[/go]
... as well as
.
Re: The most difficult yose problem
Posted: Fri Feb 11, 2022 10:40 am
by Gérard TAILLE
Cassandra wrote:Harleqin wrote:What's that funny shape in the corner?
Probably aiming at a fight for creating a seki in the corner???
$$ Komi = 0.5; no prisoners
$$ +---------------------------+
$$ | . . O X X X X . O . X X . |
$$ | . . O O O . . . O . . . . |
$$ | . . . . O X X X O O O O . |
$$ | . . . O . X , . . X X X . |
$$ | . . . O O X . X X X . X X |
$$ | . O X . O X . . . . . O . |
$$ | O O O O O X , . O X X X . |
$$ | X O X X O . X . . X O X X |
$$ | X X X . X O X . . X O O O |
$$ | . . X . . O , X X X O . . |
$$ | O 2 . X X O O O X X O . . |
$$ | X . O X O . X O X O O . . |
$$ | . X O X . O . . X X O . . |
$$ +---------------------------+
- Click Here To Show Diagram Code
[go]$$ Komi = 0.5; no prisoners
$$ +---------------------------+
$$ | . . O X X X X . O . X X . |
$$ | . . O O O . . . O . . . . |
$$ | . . . . O X X X O O O O . |
$$ | . . . O . X , . . X X X . |
$$ | . . . O O X . X X X . X X |
$$ | . O X . O X . . . . . O . |
$$ | O O O O O X , . O X X X . |
$$ | X O X X O . X . . X O X X |
$$ | X X X . X O X . . X O O O |
$$ | . . X . . O , X X X O . . |
$$ | O 2 . X X O O O X X O . . |
$$ | X . O X O . X O X O O . . |
$$ | . X O X . O . . X X O . . |
$$ +---------------------------+[/go]
Locally this
white move is good but globally it seems to me quite bad. Here again sure I missed something.
Re: The most difficult yose problem
Posted: Fri Feb 11, 2022 11:47 am
by lightvector
What if white ignores black move 17 and instead just connects the ko?