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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 2:38 pm
by lightvector
Also, what happens if on move 53 Black responds to white move 52 cut by connecting solidly? Is it worth gaining one stage in the ko to allow white to set up the squeeze and future ko threats there?

Re: The most difficult yose problem

Posted: Mon Feb 14, 2022 3:25 pm
by dany
lightvector wrote:Also, what happens if on move 53 Black responds to white move 52 cut by connecting solidly? Is it worth gaining one stage in the ko to allow white to set up the squeeze and future ko threats there?
Click Here To Show Diagram Code
[go]$$Wm52
$$ +---------------------------+
$$ | . . O X X X X X O . O . O |
$$ | . . O O O O X X O . X . O |
$$ | . . . . O X X X O O O O O |
$$ | . . . O X X , . X X X X O |
$$ | . . . O O X . X X X . X X |
$$ | . O X . O X . . . . . O . |
$$ | O O O O O X 1 . O X X X . |
$$ | X O X X O O X . . X O X X |
$$ | X X X . X O X 2 . X O O O |
$$ | . . X , X O O X X X O . X |
$$ | O O O X X O O O X X O X 3 |
$$ | . X O X O . X O X O O O X |
$$ | O X O X O O . O X X O . O |
$$ +---------------------------+[/go]
53 cost 1 point for black
black suffers from a lack of good ko threats

W+0.5

Re: The most difficult yose problem

Posted: Tue Feb 15, 2022 9:21 am
by Gérard TAILLE
dany wrote:
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 ;-)
I keep my spirits up. Let's try this new sequence:

Re: The most difficult yose problem

Posted: Tue Feb 15, 2022 12:21 pm
by dany
Gérard TAILLE wrote:
I keep my spirits up. Let's try this new sequence:

Click Here To Show Diagram Code
[go]$$Wm88
$$ +---------------------------+
$$ | . . O X X X X X O . O . O |
$$ | . . 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 1 . 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 . X |
$$ | O O O X X O O O X X O X . |
$$ | . X O X O O . O X O O O X |
$$ | O X O X O O . O X X O . O |
$$ +---------------------------+[/go]
Not the best move. Move in the bottom left corner is better

Re: The most difficult yose problem

Posted: Tue Feb 15, 2022 3:16 pm
by Gérard TAILLE
dany wrote:
Click Here To Show Diagram Code
[go]$$Wm88
$$ +---------------------------+
$$ | . . O X X X X X O . O . O |
$$ | . . 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 1 . 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 . X |
$$ | O O O X X O O O X X O X . |
$$ | . X O X O O . O X O O O X |
$$ | O X O X O O . O X X O . O |
$$ +---------------------------+[/go]
Not the best move. Move in the bottom left corner is better
Yes Dany. Though it is not the best result, it seems white is able to force an impressive 121 moves sequence.

Re: The most difficult yose problem

Posted: Tue Feb 15, 2022 4:00 pm
by dany
Gérard TAILLE wrote: Yes Dany. Though it is not the best result, it seems white is able to force an impressive 121 moves sequence.

Click Here To Show Diagram Code
[go]$$Bm93
$$ +---------------------------+
$$ | . . O X X X X X O . O . O |
$$ | . 2 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 |
$$ | . . 1 O O X . X X X . X X |
$$ | . 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 |
$$ | X X X . X O X X X X O O O |
$$ | O . X X X O O X X X O . X |
$$ | O O O X X O O O X X O X . |
$$ | O . O X O O . O X O O O X |
$$ | O X O X O O . O X X O . O |
$$ +---------------------------+[/go]
W++

Re: The most difficult yose problem

Posted: Tue Feb 15, 2022 4:17 pm
by Gérard TAILLE
dany wrote:
Click Here To Show Diagram Code
[go]$$Bm93
$$ +---------------------------+
$$ | . . O X X X X X O . O . O |
$$ | . 2 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 |
$$ | . . 1 O O X . X X X . X X |
$$ | . 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 |
$$ | X X X . X O X X X X O O O |
$$ | O . X X X O O X X X O . X |
$$ | O O O X X O O O X X O X . |
$$ | O . O X O O . O X O O O X |
$$ | O X O X O O . O X X O . O |
$$ +---------------------------+[/go]
W++
Oops sorry Dany. A notation error. This problem was already mentionned and solved.
BTW I found the final position already in the post viewtopic.php?p=270976#p270976 but with an uncorrect sequence.

Re: The most difficult yose problem

Posted: Tue Feb 15, 2022 5:43 pm
by dany
Gérard TAILLE wrote: Oops sorry Dany. A notation error. This problem was already mentionned and solved.
BTW I found the final position already in the post viewtopic.php?p=270976#p270976 but with an uncorrect sequence.

in principle, the solution too
but imho 94 white move is easier for black - black can immediately finish an unclear ko
Click Here To Show Diagram Code
[go]$$Wm94
$$ +---------------------------+
$$ | . 2 O X X X X X O . O . O |
$$ | 8 X O O O O X X O O . O O |
$$ | 6 O X X O X X X O O O O O |
$$ | 7 O X O X X , . X X X X O |
$$ | . 5 4 O O X . X X X . X X |
$$ | . 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 |
$$ | X X X . X O X X X X O O O |
$$ | O . X X X O O X X X O 3 X |
$$ | O O O X X O O O X X O X 1 |
$$ | O 9 O X O O . O X O O O . |
$$ | O X O X O O . O X X O . O |
$$ +---------------------------+[/go]
B+0.5

so I prefer white's other move, which continues the ko
Click Here To Show Diagram Code
[go]$$Wm94
$$ +---------------------------+
$$ | . . O X X X X X O . O . O |
$$ | . X O O O O X X O O . O O |
$$ | . O . . O X X X O O O O O |
$$ | . O . O X X , . X X X X O |
$$ | . . 1 O O X . X X X . X X |
$$ | . 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 |
$$ | X X X . X O X X X X O O O |
$$ | O . X X X O O X X X O . X |
$$ | O O O X X O O O X X O X . |
$$ | O . O X O O . O X O O O X |
$$ | O X O X O O . O X X O . O |
$$ +---------------------------+[/go]
P.S. with ko trick the solution can be extended by 4 moves

Re: The most difficult yose problem

Posted: Wed Feb 16, 2022 5:00 am
by Gérard TAILLE
dany wrote:
Gérard TAILLE wrote: Oops sorry Dany. A notation error. This problem was already mentionned and solved.
BTW I found the final position already in the post viewtopic.php?p=270976#p270976 but with an uncorrect sequence.

in principle, the solution too
but imho 94 white move is easier for black - black can immediately finish an unclear ko
Click Here To Show Diagram Code
[go]$$Wm94
$$ +---------------------------+
$$ | . 2 O X X X X X O . O . O |
$$ | 8 X O O O O X X O O . O O |
$$ | 6 O X X O X X X O O O O O |
$$ | 7 O X O X X , . X X X X O |
$$ | . 5 4 O O X . X X X . X X |
$$ | . 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 |
$$ | X X X . X O X X X X O O O |
$$ | O . X X X O O X X X O 3 X |
$$ | O O O X X O O O X X O X 1 |
$$ | O 9 O X O O . O X O O O . |
$$ | O X O X O O . O X X O . O |
$$ +---------------------------+[/go]
B+0.5

so I prefer white's other move, which continues the ko
Click Here To Show Diagram Code
[go]$$Wm94
$$ +---------------------------+
$$ | . . O X X X X X O . O . O |
$$ | . X O O O O X X O O . O O |
$$ | . O . . O X X X O O O O O |
$$ | . O . O X X , . X X X X O |
$$ | . . 1 O O X . X X X . X X |
$$ | . 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 |
$$ | X X X . X O X X X X O O O |
$$ | O . X X X O O X X X O . X |
$$ | O O O X X O O O X X O X . |
$$ | O . O X O O . O X O O O X |
$$ | O X O X O O . O X X O . O |
$$ +---------------------------+[/go]
P.S. with ko trick the solution can be extended by 4 moves
Oops as long as we talk about "preference" we have to define what is the objective.
For me I consider each player have to respect the best possible result. This best result being a black win by 0.5 point any move that will be a loss regarding this result has to be eliminated.
Click Here To Show Diagram Code
[go]$$Wm94
$$ +---------------------------+
$$ | . . O X X X X X O . O . O |
$$ | . X O O O O X X O O . O O |
$$ | . O . . O X X X O O O O O |
$$ | . O . O X X , . X X X X O |
$$ | . . 1 O O X . X X X . X X |
$$ | . 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 |
$$ | X X X . X O X X X X O O O |
$$ | O a X X X O O X X X O . X |
$$ | O O O X X O O O X X O X . |
$$ | O . O X O O . O X O O O X |
$$ | O X O X O O . O X X O 2 O |
$$ +---------------------------+[/go]
Here after black :b95: white cannot play at "a" because it is great loss isn't it?


For the time being, and with this respect my best sequence has "only" 101 moves:



Can you tell me if we can reach a better figure?

Re: The most difficult yose problem

Posted: Wed Feb 16, 2022 6:27 am
by jmeinh
dany wrote: ...
P.S. with ko trick the solution can be extended by 4 moves
Is this what you have meant?

Re: The most difficult yose problem

Posted: Wed Feb 16, 2022 7:17 am
by dany
jmeinh wrote:
dany wrote: ...
P.S. with ko trick the solution can be extended by 4 moves
Is this what you have meant?
Yes, this little trick))

Re: The most difficult yose problem

Posted: Wed Feb 16, 2022 7:31 am
by Gérard TAILLE
jmeinh wrote:
dany wrote: ...
P.S. with ko trick the solution can be extended by 4 moves
Is this what you have meant?
Very good point Jmeinh.
Now the longest best sequence reaches 105 moves:



My feeling is that we did not find how to use the last white potential ko threat in the center (g8, g9, h10). I guess another improvment could be found.

Re: The most difficult yose problem

Posted: Wed Feb 16, 2022 12:28 pm
by dany
Gérard TAILLE wrote:
Very good point Jmeinh.
Now the longest best sequence reaches 105 moves:



My feeling is that we did not find how to use the last white potential ko threat in the center (g8, g9, h10). I guess another improvment could be found.
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 X , . X X X X O |
$$ | . . . O O X . X X X . X X |
$$ | . O X . O X . . . O X . 1 |
$$ | O O O O O X O O O X X X . |
$$ | 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 X O O 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 |
$$ | O X O X O O . O X X O . O |
$$ +---------------------------+[/go]
87 mistake
W++ ;-)

Re: The most difficult yose problem

Posted: Wed Feb 16, 2022 2:01 pm
by jmeinh
dany wrote:
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 X , . X X X X O |
$$ | . . . O O X . X X X . X X |
$$ | . O X . O X . . . O X . 1 |
$$ | O O O O O X O O O X X X . |
$$ | 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 X O O 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 |
$$ | O X O X O O . O X X O . O |
$$ +---------------------------+[/go]
87 mistake
W++ ;-)
Yes, White suddenly has 2 more ko threats after the preparatory move G9 instead of just one. However, if Black captures the other stone, G9 gives only one more ko threat (as usual), because of the stone J8.
Click Here To Show Diagram Code
[go]$$Wm92
$$ +---------------------------+
$$ | . . O X X X X X O . O . O |
$$ | . . 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 . a X X X X O |
$$ | . . . O O X 1 X X X . X X |
$$ | . O X . O X b c . O X . X |
$$ | O O O O O X O O O X X X . |
$$ | 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 X O O 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 |
$$ | O X O X O O . O X X O . O |
$$ +---------------------------+[/go]
White starts with 'a'; if Black defends with 'b', White has the second ko threat at 'c'.

Re: The most difficult yose problem

Posted: Wed Feb 16, 2022 2:31 pm
by Gérard TAILLE
jmeinh wrote:
dany wrote:
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 X , . X X X X O |
$$ | . . . O O X . X X X . X X |
$$ | . O X . O X . . . O X . 1 |
$$ | O O O O O X O O O X X X . |
$$ | 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 X O O 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 |
$$ | O X O X O O . O X X O . O |
$$ +---------------------------+[/go]
87 mistake
W++ ;-)
Yes, White suddenly has 2 more ko threats after the preparatory move G9 instead of just one. However, if Black captures the other stone, G9 gives only one more ko threat (as usual), because of the stone J8.
Click Here To Show Diagram Code
[go]$$Wm92
$$ +---------------------------+
$$ | . . O X X X X X O . O . O |
$$ | . . 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 |
$$ | . . . O O X 1 X X X . X X |
$$ | . O X . O X . . . O X . X |
$$ | O O O O O X O O O X X X . |
$$ | 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 X O O 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 |
$$ | O X O X O O . O X X O . O |
$$ +---------------------------+[/go]
Yes of course. You mentionned already the correct move in your post viewtopic.php?p=270963#p270963. A typing error because on my goban I always played the right move.

Black wins by 0.5 points after 105 moves.

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