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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: Fri Feb 11, 2022 11:50 am
by Cassandra
Lightvector was faster with his posting, as his name already suggests :-)

Click Here To Show Diagram Code
[go]$$Bm17 Komi = 0.5; prisoners: :b2: :w1:
$$ +---------------------------+
$$ | . . O X X X X . O . X X . |
$$ | . . O O O O X . O . X . O |
$$ | . . . . O X X X O O O O 2 |
$$ | . . . O . X , . . X X X O |
$$ | . . . O O X . X X X . X X |
$$ | . 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 |
$$ | X X X . X O X . . X O O O |
$$ | . . X , X O , X X X O . 3 |
$$ | O O O X X O O O X X O X . |
$$ | X X O X O . X O X O O O X |
$$ | . X O X 4 O . . X X O . . |
$$ +---------------------------+[/go]
Now, White has a wild bunch of ko-threats in the lower left corner.

Re: The most difficult yose problem

Posted: Fri Feb 11, 2022 12:04 pm
by dany
Cassandra wrote:Lightvector was faster with his posting, as his name already suggests :-)

Click Here To Show Diagram Code
[go]$$Bm17 Komi = 0.5; prisoners: :b2: :w1:
$$ +---------------------------+
$$ | . . O X X X X . O . X X . |
$$ | . . O O O O X . O . X . O |
$$ | . . . . O X X X O O O O 2 |
$$ | . . . O . X , . . X X X O |
$$ | . . . O O X . X X X . X X |
$$ | . 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 |
$$ | X X X . X O X . . X O O O |
$$ | . . X , X O , X X X O . 3 |
$$ | O O O X X O O O X X O X . |
$$ | X X O X O . X O X O O O X |
$$ | . X O X 4 O . . X X O . . |
$$ +---------------------------+[/go]
Now, White has a wild bunch of ko-threats in the lower left corner.
up to 20 move everything is correct. subsequent moves will be more difficult

Re: The most difficult yose problem

Posted: Sat Feb 12, 2022 3:41 am
by Cassandra
Click Here To Show Diagram Code
[go]$$Bm21 Komi = 0.5; prisoners: :b2: :w1:
$$ +---------------------------+
$$ | . . O X X X X . O . X X . |
$$ | . . O O O O X . O . X . O |
$$ | . . . . O X X X O O O O O |
$$ | . . . O . X , . 3 X X X O |
$$ | . . . O O X . X X X . X X |
$$ | . 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 |
$$ | X X X . X O X . . X O O O |
$$ | . . X , X O , X X X O . X |
$$ | O O O X X O O O X X O X . |
$$ | X X O X O . X O X O O O X |
$$ | a X O X O O . 2 X X O . 1 |
$$ +---------------------------+[/go]
Black is unable to turn the lower right corner into a seki.

After :b23: White has 22 points of territory on the board, while Black has only 21.
White will gain an additional five prisoners in the seki in the lower left corner, starting with capturing at A.

Re: The most difficult yose problem

Posted: Sat Feb 12, 2022 4:35 am
by Gérard TAILLE
dany wrote:
Cassandra wrote:Lightvector was faster with his posting, as his name already suggests :-)

Click Here To Show Diagram Code
[go]$$Bm17 Komi = 0.5; prisoners: :b2: :w1:
$$ +---------------------------+
$$ | . . O X X X X . O . X X . |
$$ | . . O O O O X . O . X . O |
$$ | . . . . O X X X O O O O 2 |
$$ | . . . O . X , . . X X X O |
$$ | . . . O O X . X X X . X X |
$$ | . 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 |
$$ | X X X . X O X . . X O O O |
$$ | . . X , X O , X X X O . 3 |
$$ | O O O X X O O O X X O X . |
$$ | X X O X O . X O X O O O X |
$$ | . X O X 4 O . . X X O . . |
$$ +---------------------------+[/go]
Now, White has a wild bunch of ko-threats in the lower left corner.
up to 20 move everything is correct. subsequent moves will be more difficult
Yes Dany, for the time being I did not find the good sequence for black.
In the sequence here under white wins by 0.5 points => I need to gain still one point for black. Very hard indeed.

Re: The most difficult yose problem

Posted: Sat Feb 12, 2022 5:46 am
by dany
Gérard TAILLE wrote: Very hard indeed.
Not yet ;-)
Click Here To Show Diagram Code
[go]$$Wc
$$ +---------------------------+
$$ | . . O X X X X X O . O . O |
$$ | . . O O O O X W O O . O O |
$$ | . . . . O X X X O O O O O |
$$ | . . . O O X , . X X X X O |
$$ | . . . O O X . X X X . X X |
$$ | . 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 |
$$ | X X X X X O X . . X O O O |
$$ | O 1 X , X O X X X X O . X |
$$ | O O O X X O O O X X O X . |
$$ | . X O X O O . O X O O O X |
$$ | O O O X O O . O X X O X . |
$$ +---------------------------+[/go]
White win ko and game.

H12 unnecessary move

Re: The most difficult yose problem

Posted: Sat Feb 12, 2022 6:09 am
by Cassandra
Click Here To Show Diagram Code
[go]$$Bm65 Komi = 0.5; prisoners :w26: :b8:
$$ +---------------------------+
$$ | . . O X X X X X O . O . O |
$$ | . . O O O O X O O O . O O |
$$ | . . . . O X X X O O O O O |
$$ | . . . O O X , . X X X X O |
$$ | . . . O O X . X X X . X X |
$$ | . 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 |
$$ | X X X . X O X . . X O O O |
$$ | O 2 X X X O X X X X O . X |
$$ | O O O X X O O O X X O X . |
$$ | O X O X O O . O X O O O X |
$$ | O . O X O O . O X X O X . |
$$ +---------------------------+[/go]
Would be much better for White!!!

Re: The most difficult yose problem

Posted: Sat Feb 12, 2022 6:12 am
by Cassandra
Click Here To Show Diagram Code
[go]$$Bm39 Komi = 0.5; prisoners :b6: :w2:
$$ +---------------------------+
$$ | . . O X X X X X O X X X . |
$$ | . . O O O O X O O 1 X X O |
$$ | . . . . O X X X O O O O O |
$$ | . . . O O X , . X X X X O |
$$ | . . . O O X . X X X . X X |
$$ | . 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 |
$$ | X X X . X O X . . X O O O |
$$ | . . X , X O X X X X O . X |
$$ | O O O X X O O O X X O X . |
$$ | X X O X O . X O X O O O X |
$$ | . X O X O O a O X X O . O |
$$ +---------------------------+[/go]
Would be better for Black than A!!!

Re: The most difficult yose problem

Posted: Sat Feb 12, 2022 11:22 am
by Gérard TAILLE
Cassandra wrote:
Click Here To Show Diagram Code
[go]$$Bm39 Komi = 0.5; prisoners :b6: :w2:
$$ +---------------------------+
$$ | . . O X X X X X O X X X . |
$$ | . . O O O O X O O 1 X X O |
$$ | . . . . O X X X O O O O O |
$$ | . . . O O X , . X X X X O |
$$ | . . . O O X . X X X . X X |
$$ | . 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 |
$$ | X X X . X O X . . X O O O |
$$ | . . X , X O X X X X O . X |
$$ | O O O X X O O O X X O X . |
$$ | X X O X O . X O X O O O X |
$$ | . X O X O O a O X X O . O |
$$ +---------------------------+[/go]
Would be better for Black than A!!!
Could you explain why this :b39: is better than a move at "a"?

Re: The most difficult yose problem

Posted: Sat Feb 12, 2022 11:39 am
by Gérard TAILLE
Cassandra wrote:
Click Here To Show Diagram Code
[go]$$Bm65 Komi = 0.5; prisoners :w26: :b8:
$$ +---------------------------+
$$ | . . O X X X X X O . O . O |
$$ | . . O O O O X O O O . O O |
$$ | . . . . O X X X O O O O O |
$$ | . . . O O X , . X X X X O |
$$ | . . . O O X . X X X . X X |
$$ | . 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 |
$$ | X X X . X O X . . X O O O |
$$ | O 2 X X X O X X X X O . X |
$$ | O O O X X O O O X X O X . |
$$ | O X O X O O . O X O O O X |
$$ | O . O X O O . O X X O X . |
$$ +---------------------------+[/go]
Would be much better for White!!!
Good point Cassandra.

Re: The most difficult yose problem

Posted: Sat Feb 12, 2022 1:23 pm
by Cassandra
Gérard TAILLE wrote:Could you explain why this :b39: is better than a move at "a"?
Yes.
Order of moves is important!!!
But painting the diagrams will take a while ...

Re: The most difficult yose problem

Posted: Sat Feb 12, 2022 2:24 pm
by Gérard TAILLE
dany wrote:
Gérard TAILLE wrote: Very hard indeed.
Not yet ;-)
Click Here To Show Diagram Code
[go]$$Wc
$$ +---------------------------+
$$ | . . O X X X X X O . O . O |
$$ | . . O O O O X W O O . O O |
$$ | . . . . O X X X O O O O O |
$$ | . . . O O X , . X X X X O |
$$ | . . . O O X . X X X . X X |
$$ | . 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 |
$$ | X X X X X O X . . X O O O |
$$ | O 1 X , X O X X X X O . X |
$$ | O O O X X O O O X X O X . |
$$ | . X O X O O . O X O O O X |
$$ | O O O X O O . O X X O X . |
$$ +---------------------------+[/go]
White win ko and game.

H12 unnecessary move
I do not undersatnd Dany. If you say that H12 is an unnecessary move that means that this white move was not the best one. But white wins the game with this move ;-)
Maybe I am wrong but I expect black could win this game. That means that black played a wrong move somewhere didn't she?

Re: The most difficult yose problem

Posted: Sat Feb 12, 2022 3:14 pm
by dany
Gérard TAILLE wrote:
dany wrote:
Gérard TAILLE wrote: Very hard indeed.
Not yet ;-)
Click Here To Show Diagram Code
[go]$$Wc
$$ +---------------------------+
$$ | . . O X X X X X O . O . O |
$$ | . . O O O O X W O O . O O |
$$ | . . . . O X X X O O O O O |
$$ | . . . O O X , . X X X X O |
$$ | . . . O O X . X X X . X X |
$$ | . 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 |
$$ | X X X X X O X . . X O O O |
$$ | O 1 X , X O X X X X O . X |
$$ | O O O X X O O O X X O X . |
$$ | . X O X O O . O X O O O X |
$$ | O O O X O O . O X X O X . |
$$ +---------------------------+[/go]
White win ko and game.

H12 unnecessary move
I do not undersatnd Dany. If you say that H12 is an unnecessary move that means that this white move was not the best one. But white wins the game with this move ;-)
Maybe I am wrong but I expect black could win this game. That means that black played a wrong move somewhere didn't she?
You played H12 before white pass series. White has no reason to play H12 instead of simple pass

Re: The most difficult yose problem

Posted: Sat Feb 12, 2022 3:19 pm
by dany
Gérard TAILLE wrote:
dany wrote:
Gérard TAILLE wrote: Very hard indeed.
Not yet ;-)
Click Here To Show Diagram Code
[go]$$Wc
$$ +---------------------------+
$$ | . . O X X X X X O . O . O |
$$ | . . O O O O X W O O . O O |
$$ | . . . . O X X X O O O O O |
$$ | . . . O O X , . X X X X O |
$$ | . . . O O X . X X X . X X |
$$ | . 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 |
$$ | X X X X X O X . . X O O O |
$$ | O 1 X , X O X X X X O . X |
$$ | O O O X X O O O X X O X . |
$$ | . X O X O O . O X O O O X |
$$ | O O O X O O . O X X O X . |
$$ +---------------------------+[/go]
White win ko and game.
Maybe I am wrong but I expect black could win this game. That means that black played a wrong move somewhere didn't she?
Let's wait for Cassandra's diagrams

Re: The most difficult yose problem

Posted: Sat Feb 12, 2022 3:54 pm
by Gérard TAILLE
dany wrote: Not yet ;-)
Click Here To Show Diagram Code
[go]$$Wc
$$ +---------------------------+
$$ | . . O X X X X X O . O . O |
$$ | . . O O O O X W O O . O O |
$$ | . . . . O X X X O O O O O |
$$ | . . . O O X , . X X X X O |
$$ | . . . O O X . X X X . X X |
$$ | . 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 |
$$ | X X X X X O X . . X O O O |
$$ | O 1 X , X O X X X X O . X |
$$ | O O O X X O O O X X O X . |
$$ | . X O X O O . O X O O O X |
$$ | O O O X O O . O X X O X . |
$$ +---------------------------+[/go]
White win ko and game.
Seeing the white move :w1: in the diagram above I tried to change black moves. The sequence seems better ... but white wins again by 0.5 points ;-) ;-) ;-)

Re: The most difficult yose problem

Posted: Sat Feb 12, 2022 4:08 pm
by jmeinh
Does the order of the moves really matter?
Black can remove the D4 ko threat, and then White must do the same with the ko threat on 'a'. After that there is only one order of moves for Black.
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