The most difficult yose problem

Cassandra · **#21**

Click Here To Show Diagram Code: [go]$$Bm65 Komi = 0.5; prisoners $$ +---------------------------+ $$ | . . O X X X X X O . O . O | $$ | . . 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!!!

Cassandra · **#22**

Click Here To Show Diagram Code: [go]$$Bm39 Komi = 0.5; prisoners $$ +---------------------------+ $$ | . . O X X X X X O X X X . | $$ | . . 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!!!

Gérard TAILLE · **#23**

Cassandra wrote:

Click Here To Show Diagram Code: [go]$$Bm39 Komi = 0.5; prisoners $$ +---------------------------+ $$ | . . O X X X X X O X X X . | $$ | . . 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"?

Gérard TAILLE · **#24**

Cassandra wrote:

Click Here To Show Diagram Code: [go]$$Bm65 Komi = 0.5; prisoners $$ +---------------------------+ $$ | . . O X X X X X O . O . O | $$ | . . 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.

Cassandra · **#25**

Gérard TAILLE wrote:

Could you explain why this :b39:

is better than a move at "a"?

Yes.

But painting the diagrams will take a while ...

Gérard TAILLE · **#26**

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?

dany · **#27**

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

dany · **#28**

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

Gérard TAILLE · **#29**

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 ;-)

jmeinh · **#30**

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.

dany · **#31**

Gérard TAILLE wrote:

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 ;-)

Very interesting variation :tmbup:

And new for my variations tree

Cassandra · **#32**

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 :b49:

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 · **#33**

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 · **#34**

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

dany · **#35**

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 · **#36**

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 · **#37**

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 · **#38**

jmeinh wrote:

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

No. "Column #3: Black loses a ko-threat, as :b49:

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

Cassandra · **#39**

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 ...
:lol:

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 :b57:

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 · **#40**

Gérard TAILLE wrote:

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

Yes

The most difficult yose problem

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