The most difficult yose problem

dany · Post by **dany** » Sat Feb 12, 2022 4:29 pm

Gérard TAILLE wrote: Seeing the white move in the diagram above I tried to change black moves. The sequence seems better ... but white wins again by 0.5 points

Very interesting variation

And new for my variations tree

Cassandra · Post by **Cassandra** » Sat Feb 12, 2022 4:38 pm

Early ko-threat at the bottom / Ko-threat in the upper right first / VAR of column #1

Click Here To Show Diagram Code: [go]$$Bm39 $$ --------------------------------------------------------- $$ - . . O X X X X X O X X X . - . . O X X X X X O X X X 2 - $$ - . . O O O O X O O . X X O - . . O O O O X O O 1 X X O - $$ - . . . . O X X X O O O O O - . . . . O X X X O O O O O - $$ - . . . O O X , . X X X X O - . . . O O X , . X X X X O - $$ - . . . O O X . X X X . X X - . . . O O X . X X X . X X - $$ - . O X . O X . . . . . O . - . O X . O X . . . . . O . - $$ - O O O O O X , . O X X X . - O O O O O X , . O X X X . - $$ - X O X X O O X . . X O X X - X O X X O O X . . X O X X - $$ - X X X . X O X . . X O O O - X X X . X O X . . X O O O - $$ - . . X , X O X X X X O . X - . . X , X O X X X X O . X - $$ - O O O X X O O O X X O X . - O O O X X O O O X X O X . - $$ - X X O X O 1 X O X O O O X - X X O X O . X O X O O O X - $$ - 4 X O X O O 2 O X X O 3 O - 4 X O X O O . O X X O 3 O - $$ ---------------------------------------------------------[/go]

Click Here To Show Diagram Code: [go]$$Bm43 $$ --------------------------------------------------------- $$ - . . O X X X X X O X X X . - . . O X X X X X O . . . O - $$ - . . O O O O X O O . X X O - . . O O O O X O O . . . O - $$ - . . . . O X X X O O O O O - . . . . O X X X O O O O O - $$ - . . . O O X , . X X X X O - . . . O O X , . X X X X O - $$ - . . . O O X . X X X . X X - . . . O O X . X X X . X X - $$ - . O X . O X . . . . . O . - . O X . O X . . . . . O . - $$ - O O O O O X , . O X X X . - O O O O O X , . O X X X . - $$ - X O X X O O X . . X O X X - X O X X O O X . . X O X X - $$ - X X X . X O X . . X O O O - X X X . X O X . . X O O O - $$ - . . X , X O X X X X O . X - . . X , X O X X X X O . X - $$ - O O O X X O O O X X O X . - O O O X X O O O X X O X . - $$ - . 1 O X O . . O X O O O X - . 1 O X O . X O X O O O X - $$ - O . O X O O O O X X O X 2 - O . O X O O . O X X O X 2 - $$ ---------------------------------------------------------[/go]

Click Here To Show Diagram Code: [go]$$Bm45 $$ ------------------------------------------------------------------------------------- $$ - . . O X X X X X O X X X 2 - . . O X X X X X O . . . O - . . O X X X X X O X X X . - $$ - . . O O O O X O O 1 X X O - . . O O O O X O O . . . O - . . O O O O X O O . X X O - $$ - . . . . O X X X O O O O O - . . . . O X X X O O O O O - . . . . O X X X O O O O O - $$ - . . . O O X , . X X X X O - . . . O O X , . X X X X O - . . . O O X , . X X X X O - $$ - . . . O O X . X X X . X X - . . . O O X . X X X . X X - . . . O O X . X X X . X X - $$ - . O X . O X . . . . . O . - . O X . O X . . . . . O . - . O X . O X . . . . . O . - $$ - O O O O O X , . O X X X . - O O O O O X , . O X X X . - O O O O O X , . O X X X . - $$ - X O X X O O X . . X O X X - X O X X O O X . . X O X X - X O X X O O X . . X O X X - $$ - X X X . X O X . . X O O O - X X X . X O X . . X O O O - X X X . X O X . . X O O O - $$ - . . X , X O X X X X O . X - . . X , X O X X X X O . X - . . X , X O X X X X O . X - $$ - O O O X X O O O X X O X . - O O O X X O O O X X O X 2 - O O O X X O O O X X O X 2 - $$ - . X O X O . . O X O O O X - . X O X O . X O X O O O X - . X O X O . . O X O O O X - $$ - O . O X O O O O X X O 3 O - O 1 O X O O . O X X O . O - O 1 O X O O O O X X O . O - $$ -------------------------------------------------------------------------------------[/go]

Column #2: White cannot win the ko-fight in only one move, so Black is able to erase a White ko-threat.
Column #3: However, this "trick" does not work if the upper right corner is touched too late.

Click Here To Show Diagram Code: [go]$$Bm47 $$ ------------------------------------------------------------------------------------- $$ - . . O X X X X X O . . . O - . . O X X X X X O . 2 . O - . . O X X X X X O X X X 2 - $$ - . . O O O O X O O . . . O - . . O O O O X O O . 1 . O - . . O O O O X O O 1 X X O - $$ - . . . . O X X X O O O O O - . . . . O X X X O O O O O - . . . . O X X X O O O O O - $$ - . . . O O X , . X X X X O - . . . O O X , . X X X X O - . . . O O X , . X X X X O - $$ - . . . O O X . X X X . X X - . . . O O X . X X X . X X - . . . O O X . X X X . X X - $$ - . O X . O X . . . . . O . - . O X . O X . . . . . O . - . O X . O X . . . . . O . - $$ - O O O O O X , . O X X X . - O O O O O X , . O X X X . - O O O O O X , . O X X X . - $$ - X O X X O O X . . X O X X - X O X X O O X . . X O X X - X O X X O O X . . X O X X - $$ - X X X . X O X . . X O O O - X X X . X O X . . X O O O - X X X . X O X . . X O O O - $$ - 2 . X , X O X X X X O . X - . . X , X O X X X X O . X - . . X , X O X X X X O . X - $$ - O O O X X O O O X X O X . - O O O X X O O O X X O X O - O O O X X O O O X X O X O - $$ - . X O X O . . O X O O O X - . X O X O . X O X O O O 3 - . X O X O . . O X O O O . - $$ - O 3 O X O O O O X X O X 4 - O X O X O O . O X X O . O - O X O X O O O O X X O . O - $$ -------------------------------------------------------------------------------------[/go]

Click Here To Show Diagram Code: [go]$$Bm49 $$ ------------------------------------------------------------------------------------- $$ - . . O X X X X X O . 4 . O - . . O X X X X X O . O . O - . . O X X X X X O . 2 . O - $$ - . . O O O O X O O . 3 . O - . . O O O O X O O . X . O - . . O O O O X O O . 1 . O - $$ - . . . . O X X X O O O O O - . . . . O X X X O O O O O - . . . . O X X X O O O O O - $$ - . . . O O X , . X X X X O - . . . O O X , . X X X X O - . . . O O X , . X X X X O - $$ - . . . O O X . X X X . X X - . . . O O X . X X X . X X - . . . O O X . X X X . X X - $$ - . O X . O X . . . . . O . - . O X . O X . . . . . O . - . O X . O X . . . . . O . - $$ - O O O O O X , . O X X X . - O O O O O X , . O X X X . - O O O O O X , . O X X X . - $$ - X O X X O O X . . X O X X - X O X X O O X . . X O X X - X O X X O O X . . X O X X - $$ - X X X . X O X . . X O O O - X X X . X O X . . X O O O - X X X . X O X . . X O O O - $$ - O . X , X O X X X X O . X - . . X , X O X X X X O . X - . . X , X O X X X X O . X - $$ - O O O X X O O O X X O X . - O O O X X O O O X X O X . - O O O X X O O O X X O X O - $$ - . X O X O . . O X O O O X - 2 X O X O . X O X O O O X - . X O X O . . O X O O O 3 - $$ - O X O X O O O O X X O 5 O - O X O X O O . O X X O 3 O - O X O X O O O O X X O . O - $$ -------------------------------------------------------------------------------------[/go]

Column #3: Black loses a ko-threat, as

is mandatory here.

Click Here To Show Diagram Code: [go]$$Wm52 $$ ------------------------------------------------------------------------------------- $$ - . . O X X X X X O . O . O - . . O X X X X X O . O . O - . . O X X X X X O . O . O - $$ - . . O O O O X O O . X . O - . . O O O O X O O . X . O - . . O O O O X O O . X . O - $$ - . . . . O X X X O O O O O - . . . . O X X X O O O O O - . . . . O X X X O O O O O - $$ - . . . O O X , . X X X X O - . . . O O X , . X X X X O - . . . O O X , . X X X X O - $$ - . . . O O X . X X X . X X - . . . O O X . X X X . X X - . . . O O X . X X X . X X - $$ - . O X . O X . . . . . O . - . O X . O X . . . . . O . - . O X . O X . . . . . O . - $$ - O O O O O X , . O X X X . - O O O O O X , . O X X X . - O O O O O X , . O X X X . - $$ - X O X X O O X . . X O X X - X O X X O O X . . X O X X - X O X X O O X . . X O X X - $$ - X X X 4 X O X . . X O O O - X X X 2 X O X . . X O O O - X X X 2 X O X . . X O O O - $$ - O . X 3 X O X X X X O . X - . . X 1 X O X X X X O . X - . . X 1 X O X X X X O . X - $$ - O O O X X O O O X X O X . - O O O X X O O O X X O X . - O O O X X O O O X X O X 3 - $$ - . X O X O . . O X O O O X - O . O X O . X O X O O O X - . X O X O . . O X O O O X - $$ - O X O X O O O O X X O X 5 - O . O X O O . O X X O X 3 - O X O X O O O O X X O . O - $$ -------------------------------------------------------------------------------------[/go]

Click Here To Show Diagram Code: [go]$$Bm55 $$ ------------------------------------------------------------------------------------- $$ - . . O X X X X X O 3 O . O - . . O X X X X X O . O . O - . . O X X X X X O 1 O . O - $$ - . . O O O O X O O 4 X . O - . . O O O O X O O . X . O - . . O O O O X O O 2 X . O - $$ - . . . . O X X X O O O O O - . . . . O X X X O O O O O - . . . . O X X X O O O O O - $$ - . . . O O X , . X X X X O - . . . O O X , . X X X X O - . . . O O X , . X X X X O - $$ - . . . O O X . X X X . X X - . . . O O X . X X X . X X - . . . O O X . X X X . X X - $$ - . O X . O X . . . . . O . - . O X . O X . . . . . O . - . O X . O X . . . . . O . - $$ - O O O O O X , . O X X X . - O O O O O X , . O X X X . - O O O O O X , . O X X X . - $$ - X O X X O O X . . X O X X - X O X X O O X . . X O X X - X O X X O O X . . X O X X - $$ - X X X X X O X . . X O O O - X X X X X O X . . X O O O - X X X X X O X . . X O O O - $$ - O . X , X O X X X X O . X - . . X , X O X X X X O . X - . . X . X O X X X X O . X - $$ - O O O X X O O O X X O X . - O O O X X O O O X X O X . - O O O X X O O O X X O X O - $$ - 6 X O X O . . O X O O O X - O . O X O 1 X O X O O O X - . X O X O . . O X O O O 3 - $$ - O X O X O O O O X X O 5 O - O . O X O O 2 O X X O 3 O - O X O X O O O O X X O . O - $$ -------------------------------------------------------------------------------------[/go]

Click Here To Show Diagram Code: [go]$$Wm58 $$ ------------------------------------------------------------------------------------- $$ - . . O X X X X X O . O . O - . . O X X X X X O . O . O - . . O X X X X X O . O . O - $$ - . . O O O O X O O O X . O - . . O O O O X O O . X . O - . . O O O O X O O O X . O - $$ - . . . . O X X X O O O O O - . . . . O X X X O O O O O - . . . . O X X X O O O O O - $$ - . . . O O X , . X X X X O - . . . O O X , . X X X X O - . . . O O X , . X X X X O - $$ - . . . O O X . X X X . X X - . . . O O X . X X X . X X - . . . O O X . X X X . X X - $$ - . O X . O X . . . . . O . - . O X . O X . . . . . O . - . O X . O X . . . . . O . - $$ - O O O O O X , . O X X X . - O O O O O X , . O X X X . - O O O O O X , . O X X X . - $$ - X O X X O O X . . X O X X - X O X X O O X . . X O X X - X O X X O O X . . X O X X - $$ - X X X X X O X . . X O O O - X X X X X O X . . X O O O - X X X X X O X . . X O O O - $$ - O . X , X O X X X X O . X - 1 . X , X O X X X X O . X - . . X . X O X X X X O . X - $$ - O O O X X O O O X X O X . - O O O X X O O O X X O X . - O O O X X O O O X X O X . - $$ - O . O X O . . O X O O O X - O . O X O . . O X O O O X - 1 X O X O . . O X O O O X - $$ - O 4 O X O O O O X X O X 5 - O 2 O X O O O O X X O X 3 - O X O X O O O O X X O 2 O - $$ -------------------------------------------------------------------------------------[/go]

Click Here To Show Diagram Code: [go]$$Wm60 $$ ------------------------------------------------------------------------------------- $$ - . . O X X X X X O . O 4 O - . . O X X X X X O 2 O . O - . . O X X X X X O . O . O - $$ - . . O O O O X O O O X 5 O - . . O O O O X O O 3 X . O - . . O O O O X O O O X . O - $$ - . . . . O X X X O O O O O - . . . . O X X X O O O O O - . . . . O X X X O O O O O - $$ - . . . O O X , . X X X X O - . . . O O X , . X X X X O - . . . O O X , . X X X X O - $$ - . . . O O X . X X X . X X - . . . O O X . X X X . X X - . . . O O X . X X X . X X - $$ - . O X . O X . . . . . O . - . O X . O X . . . . . O . - . O X . O X . . . . . O . - $$ - O O O O O X , . O X X X . - O O O O O X , . O X X X . - O O O O O X , . O X X X . - $$ - X O X X O O X . . X O X X - X O X X O O X . . X O X X - X O X X O O X . . X O X X - $$ - X X X X X O X . . X O O O - X X X X X O X . . X O O O - X X X X X O X . . X O O O - $$ - O . X , X O X X X X O . X - O . X , X O X X X X O . X - 1 . X . X O X X X X O . X - $$ - O O O X X O O O X X O X . - O O O X X O O O X X O X . - O O O X X O O O X X O X . - $$ - O . O X O . . O X O O O X - O X O X O . . O X O O O X - O . O X O . . O X O O O X - $$ - O X O X O O O O X X O 6 O - O . O X O O O O X X O 4 O - O 2 O X O O O O X X O X 3 - $$ -------------------------------------------------------------------------------------[/go]

Click Here To Show Diagram Code: [go]$$Bm63 $$ ------------------------------------------------------------------------------------- $$ - . . O X X X X X O . O . O - . . O X X X X X O . O b O - . . O X X X X X O . O 1 O - $$ - . . O O O O X O O O . O O - . . O O O O X O O O X . O - . . O O O O X O O O X 2 O - $$ - . . . . O X X X O O O O O - . . . . O X X X O O O O O - . . . . O X X X O O O O O - $$ - . . . O O X , . X X X X O - . . . O O X , . X X X X O - . . . O O X , . X X X X O - $$ - . . . O O X . X X X . X X - . . . O O X . X X X . X X - . . . O O X . X X X . X X - $$ - . O X . O X . . . . . O . - . O X . O X . . . . . O . - . O X . O X . . . . . O . - $$ - O O O O O X , . O X X X . - O O O O O X , . O X X X . - O O O O O X , . O X X X . - $$ - X O X X O O X . . X O X X - X O X X O O X . . X O X X - X O X X O O X . . X O X X - $$ - X X X X X O X . . X O O O - X X X X X O X . . X O O O - X X X X X O X . . X O O O - $$ - O 4 X , X O X X X X O . X - O a X , X O X X X X O 3 X - O . X . X O X X X X O . X - $$ - O O O X X O O O X X O X . - O O O X X O O O X X O X . - O O O X X O O O X X O X . - $$ - O . O X O . . O X O O O X - O X O X O . . O X O O O X - O . O X O . . O X O O O X - $$ - O X O X O O O O X X O X . - O 2 O X O O O O X X O X . - O X O X O O O O X X O 3 O - $$ -------------------------------------------------------------------------------------[/go]

Column #2: White A does not work here, as Black has a ko-threat at B left.

Click Here To Show Diagram Code: [go]$$Wm66 $$ ------------------------------------------------------------------------------------- $$ - . . O X X X X X O . O . O - . . O X X X X X O . O . O - . . O X X X X X O . O . O - $$ - . . O O O O X O O O . O O - . . O O O O X O O O X . O - . . O O O O X O O O . O O - $$ - . . . . O X X X O O O O O - . . . . O X X X O O O O O - . . . . O X X X O O O O O - $$ - . . . O O X , . X X X X O - . . . O O X , . X X X X O - . . . O O X , . X X X X O - $$ - . . . O O X . X X X . X X - . . . O O X . X X X . X X - . . . O O X . X X X . X X - $$ - . O X . O X . . . . . O . - . O X . O X . . . . . O . - . O X . O X . . . . . O . - $$ - O O O O O X , . O X X X . - O O O O O X , . O X X X . - O O O O O X , . O X X X . - $$ - X O X X O O X . . X O X X - X O X X O O X . . X . X X - X O X X O O X . . X O X X - $$ - X X X X X O X . . X O O O - X X X X X O X . . X . . . - X X X X X O X . . X O O O - $$ - O O X , X O X X X X O 7 X - . O X , X O X X X X . X X - O 1 X . X O X X X X O 7 X - $$ - O O O X X O O O X X O X 5 - O O O X X O O O X X . X . - O O O X X O O O X X O X 5 - $$ - O 2 O X O . . O X O O O X - O . O X O . . O X . . . X - O 2 O X O . . O X O O O X - $$ - O X O X O O O O X X O X 3 - O O O X O O O O X X . X . - O X O X O O O O X X O X 3 - $$ -------------------------------------------------------------------------------------[/go]

Column #1: White +
Column #2: Black + 0.5
Column #3: White +

jmeinh · Post by **jmeinh** » Sat Feb 12, 2022 5:52 pm

Very nice!
Although it won't work if Black uses D4 instead of A1 as a ko threat on move 42, Black can fix that by removing the D4 ko threat before the start of the ko fight.

Gérard TAILLE · Post by **Gérard TAILLE** » Sun Feb 13, 2022 4:36 am

If I understand correctly the solution of this problem is the following uncredible sequence:

dany · Post by **dany** » Sun Feb 13, 2022 5:11 am

Gérard TAILLE wrote:If I understand correctly the solution of this problem is the following uncredible sequence:

I don't think this is a solution. Due to columns 1,3 in Cassandra's diagrams.
Move 35 and 38 are mistakes

jmeinh · Post by **jmeinh** » Sun Feb 13, 2022 7:07 am

I would think at the moment:
- it is actually a solution
- column 3 has a mistake (move 49 should better be N2)
- my idea to remove a ko threat at D4/D5 leads to a decisive loss of 1 point and is therefore an error.

Gérard TAILLE · Post by **Gérard TAILLE** » Sun Feb 13, 2022 7:49 am

dany wrote:
Gérard TAILLE wrote:If I understand correctly the solution of this problem is the following uncredible sequence:

I don't think this is a solution. Due to columns 1,3 in Cassandra's diagrams.
Move 35 and 38 are mistakes

Oh yes Dany. I confess i did not see this last (?) subtility.
Here is the corrected sequence

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 . | $$ | . . . O O X . X X B . X X | $$ | . O B . O X . . . . . W . | $$ | O O O O O X , . W X X X . | $$ | 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]

BTW what is the meaning of the marked stones above.
IOW what about the following position:

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 . | $$ | . . . O O X . X X . . X X | $$ | . O . . O X . . . . . . . | $$ | O O O O O X , . . X X X . | $$ | 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]

dany · Post by **dany** » Sun Feb 13, 2022 8:10 am

jmeinh wrote: - column 3 has a mistake (move 49 should better be N2)

No. "Column #3: Black loses a ko-threat, as

is mandatory here."
If black N2 then white 49 and erase black ko threats

Cassandra · Post by **Cassandra** » Sun Feb 13, 2022 8:13 am

jmeinh wrote:- column 3 has a mistake (move 49 should better be N2)

Had a mismatch in the numbering of the moves, so dany got the change to prevail ...

Whatsoever, here comes the sequence for additional clarity:

Click Here To Show Diagram Code: [go]$$Bm49 $$ +---------------------------+ $$ | . . O X X X X X O . . . O | $$ | . . O O O O X O O . 2 . 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 | $$ | X X X 4 X O X . . X O O O | $$ | . . X 5 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 X O O O 1 | $$ | O X O X O O O O X X O 3 O | $$ +---------------------------+[/go]

Really

in the lower right corner?

Click Here To Show Diagram Code: [go]$$Wm54 $$ +---------------------------+ $$ | . . O X X X X X O 4 2 6 O | $$ | . . O O O O X 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 | $$ | X X X . X O X . . X O O O | $$ | . . X X X O X X X X O 5 X | $$ | O O O X X O O O X X O X 3 | $$ | . X O X O . . O X O O O X | $$ | O X O X O O O O X X O X 1 | $$ +---------------------------+[/go]

White ++.

White could also answer

with

, as she still has a ko-threat in the lower left corner.
Whatsoever, White's upper left corner cannot be killed any longer, so White gets a large win even with a seki there.

dany · Post by **dany** » Sun Feb 13, 2022 8:17 am

Gérard TAILLE wrote: Oh yes Dany. I confess i did not see this last (?) subtility.
Here is the corrected sequence

Yes

dany · Post by **dany** » Sun Feb 13, 2022 8:25 am

Gérard TAILLE wrote:
$$c Black to play, komi 0.5
$$ +---------------------------+
$$ | . . O X X X X . O . X X . |
$$ | . . O O O . . . O . . . . |
$$ | . . . . O X X X O O O O . |
$$ | . . . O . X , . . X X X . |
$$ | . . . O O X . X X B . X X |
$$ | . O B . O X . . . . . W . |
$$ | O O O O O X , . W X X X . |
$$ | 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 . | $$ | . . . O O X . X X B . X X | $$ | . O B . O X . . . . . W . | $$ | O O O O O X , . W X X X . | $$ | 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]
BTW what is the meaning of the marked stones above.

Good question

Hint 1. The problem's main diamonds are still hidden
Hint 2. The solution is much longer

Gérard TAILLE · Post by **Gérard TAILLE** » Sun Feb 13, 2022 8:39 am

dany wrote:
Gérard TAILLE wrote:
$$c Black to play, komi 0.5
$$ +---------------------------+
$$ | . . O X X X X . O . X X . |
$$ | . . O O O . . . O . . . . |
$$ | . . . . O X X X O O O O . |
$$ | . . . O . X , . . X X X . |
$$ | . . . O O X . X X B . X X |
$$ | . O B . O X . . . . . W . |
$$ | O O O O O X , . W X X X . |
$$ | 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 . | $$ | . . . O O X . X X B . X X | $$ | . O B . O X . . . . . W . | $$ | O O O O O X , . W X X X . | $$ | 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]
BTW what is the meaning of the marked stones above.
Good question

Hint 1. The problem's main diamonds are still hidden
Hint 2. The solution is much longer

What do mean by your Hint2 ? I do not get the point.

Cassandra · Post by **Cassandra** » Sun Feb 13, 2022 8:43 am

Gérard TAILLE wrote:BTW what is the meaning of the marked stones above.

Click Here To Show Diagram Code: [go]$$B Komi = 0.5 $$ +---------------------------+ $$ | . . O X X X X . O . X X . | $$ | . Z O O O W B . O . . . . | $$ | . . Z . O X X X O O O O . | $$ | . . . O B X , . . X X X . | $$ | . # . O O X . X X X . X X | $$ | . O Y . 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]

I do not have any idea for the right side, but for the upper left corner ...

If White's upper string got into some kind of damezumari (through something like

, concrete sequence still unknown), Black might get the change to place the two

stones, due to the multi-stage-ko in the lower right corner.
Thereafter,

might become interesting, at least as a ko threat.
And suddenly, there might be some kind of semeai (at least the threat of a seki), as White's group does not have sooo many liberties thereafter ...

With regard to the upper left corner, we will have to remember that Black might be able to play at least two moves in a row locally, probably three.

dany · Post by **dany** » Sun Feb 13, 2022 8:47 am

Gérard TAILLE wrote:
dany wrote:
Gérard TAILLE wrote:
$$c Black to play, komi 0.5
$$ +---------------------------+
$$ | . . O X X X X . O . X X . |
$$ | . . O O O . . . O . . . . |
$$ | . . . . O X X X O O O O . |
$$ | . . . O . X , . . X X X . |
$$ | . . . O O X . X X B . X X |
$$ | . O B . O X . . . . . W . |
$$ | O O O O O X , . W X X X . |
$$ | 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 . | $$ | . . . O O X . X X B . X X | $$ | . O B . O X . . . . . W . | $$ | O O O O O X , . W X X X . | $$ | 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]
BTW what is the meaning of the marked stones above.
Good question

Hint 1. The problem's main diamonds are still hidden
Hint 2. The solution is much longer
What do mean by your Hint2 ? I do not get the point.

The current solution has 67 moves. The real solution has over 100 moves

jmeinh · Post by **jmeinh** » Sun Feb 13, 2022 9:35 am

dany wrote:
jmeinh wrote: - column 3 has a mistake (move 49 should better be N2)
No. "Column #3: Black loses a ko-threat, as is mandatory here."
If black N2 then white 49 and erase black ko threats

thank you, I had somehow overlooked this comment. (Now I feel dizzy...)

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