Beat Elf!

Bill Spight · **#21**

The third one comes from GoGoD 1996-01-31a, between Kobayashi Satoru (W) and Cho Chikun. I found it when I was looking for a game for How is your positional judgement? ( https://lifein19x19.com/viewtopic.php?f=15&t=16909 ).

Earlier in the game.

Click Here To Show Diagram Code: [go]$$Bcm7 White blunders $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . O 4 5 . . . | $$ | . . . O . . . . . , . . 9 1 2 X 0 . . | $$ | . . . . . . . . . . . . . . 3 6 7 . . | $$ | . . . . . . . . . . . . . . . 8 a . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . X . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . O . . . . . , . . . . . X . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

Cho played sanrensei and played the jump attachment, :b7:

, against Kobayashi's approach. Kobayashi replied with the unorthodox wedge. (Elf's choice is 10.) I suspect that Cho set a trap for White with :b15:

. If so, White fell into it with :w16:

. In any event, :w16:

is a blunder. According to Elf it loses 23% by comparison with a.

Click Here To Show Diagram Code: [go]$$Bcm17 A tale of two ladders $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . O O X 1 . . | $$ | . . . O . . . . . , . a X X O X O c . | $$ | . . . . . . . . . . . . 4 2 X O X . . | $$ | . . . . . . . . . . . . . . 3 O . . . | $$ | . . . . . . . . . . . . . . b . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . X . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . O . . . . . , . . . . . X . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

With

and

Kobayashi set up two possible ladders at a and b. Elf recommends c instead. This two ladder setup is a common tactic when the shape is one line closer to the top side. I'm sure that Kobayashi had seen classical problems and ancient game records with Black's refutation. Maybe he was having a bad day. Elf's winrate estimate is skewed by the fact that Elf had perhaps never played the refutation against itself in its training. We can estimate White's loss at around 18%.

Click Here To Show Diagram Code: [go]$$Bcm21 Off with their heads! $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . O O X X . . | $$ | . . . O . . . . . , . . X X O X O . . | $$ | . . . . . . . . . . . 1 O O X O X . . | $$ | . . . . . . . . . . . 6 4 3 X O . . . | $$ | . . . . . . . . . . 7 . . 5 2 a . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . X . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . O . . . . . , . . . . . X . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

The double ladder breaker, :b27:

, was completely off Elf's radar (0 playouts). Elf's first choice was a (241.8k playouts), for a comparative loss of 18½%. Go Seigen criticized Cho Chikun for taking too much time in the opening. But in this case Cho might have played :b27:

in two seconds flat.

It is obvious that :b27:

breaks the ladder from the right, but where is this ladder from the top? Glad you asked. :cool:

Click Here To Show Diagram Code: [go]$$Wcm28 The other ladder $$ --------------------------------------- $$ | . . . . . . . . . . 9 8 . . . . . . . | $$ | . . . . . . . . . . 7 6 3 . . . . . . | $$ | . . . . . . . . . . 5 4 2 O O X X . . | $$ | . . . O . . . . . , 0 1 X X O X O . . | $$ | . . . . . . . . . . . X O O X O X . . | $$ | . . . . . . . . . . . O O X X O . . . | $$ | . . . . . . . . . . X . . X O . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . X . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . O . . . . . , . . . . . X . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

White pushes Black to the edge, then :b37:

captures

.

Click Here To Show Diagram Code: [go]$$Wcm38 The other ladder, continued $$ --------------------------------------- $$ | . . . . . . . . . . O X 1 . . . . . . | $$ | . . . . . . . . . . O X O . . . . . . | $$ | . . . . . . . . . . O X X O O X X . . | $$ | . . . O . . . . . 3 X 2 X X O X O . . | $$ | . . . . . . . . . . 4 X O O X O X . . | $$ | . . . . . . . . . . . O O X X O . . . | $$ | . . . . . . . . . . B . . X O . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . X . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . O . . . . . , . . . . . X . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

is atari. After :b39:

fills,

starts the ladder up again. This kind of ladder is called a spiral ladder ( https://senseis.xmp.net/?TurnaroundLadder ). Anyway, it is now obvious that :bc:

breaks it.

bernds · **#22**

Bill Spight wrote:

I ran across this one the other day.

Click Here To Show Diagram Code: [go]$$Wcm26 Black to play. $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . O O X X . . | $$ | . . . O . . . . . , . . X X O X O . . | $$ | . . . . . . . . . . . X O O X O X . . | $$ | . . . . . . . . . . . O O X X O . . . | $$ | . . . . . . . . . . . . . X O . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . X . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . O . . . . . , . . . . . X . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

Tryss · **#23**

was also off Katago radar. With 100k playout, it didn't explore it, and when played, it's a +25% move (or about 10 pts).

This is how Katago try to salvage the situation :

Click Here To Show Diagram Code: [go]$$Wcm28 Katago choice (38-39-40 at a-b-c) $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . a 7 1 . . . . . 0 . | $$ | . . . . . . . . 8 . 6 . . O O X X 9 . | $$ | . . . O . . . . . , . 2 X X O X O 3 . | $$ | . . . . . . . . . . . X O O X O X 4 . | $$ | . . . . . . . . c . 5 O O X X O . . . | $$ | . . . . . . . . . . X . . X O b . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . X . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . O . . . . . , . . . . . X . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

And it put white at 30% winrate, with -9 pts

Bill Spight · **#24**

A whopper for Elf, according to itself.

Click Here To Show Diagram Code: [go]$$Bcm15 Elf's choice for move 115 $$ --------------------------------------- $$ | . . . . . . . . . . . . X X X X . . . | $$ | . . . . . . . . . . . X O X O X O O . | $$ | . . . O . . X . . . X . O X O X O . O | $$ | . . O , O . . . . , . . O X O X X O . | $$ | . . X . X X . . . X X O O O O X . X . | $$ | . . . . . . . . . . O X X 1 . O X . . | $$ | . . . . . . . . . . O . . X O O . . . | $$ | . . . . . . . . . . . O . X . O X . . | $$ | . . O . . . . . O . . . X . X O O . . | $$ | . . . , . . . . . O X O . . . , X . . | $$ | . . . . . . . . . O O X . . X . O . . | $$ | . . O . . . . . . X X . X X O O . . . | $$ | . . . . . . . X . . . . . O X O . . . | $$ | . . . O . . . X O O . X O . X . . . . | $$ | . . O . O . X O X . . O . . O O . . . | $$ | . . X O O . . . X , O . X X . , O . . | $$ | . . X X O . . X . . . . . O . X O . . | $$ | . . . . X . . . . . . . . . X . X . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

Elf's peep, by its own reckoning, loses 28% to Rittetsu's play.

If you can find it, you're a better man than I am.

Bill Spight · **#25**

On the third day of Christmas

Click Here To Show Diagram Code: [go]$$Bcm33 Kato Masao (W) - Cho Chikun, one prisoner each $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . O 1 . . . . . . . . . . . . . . . | $$ | . O X O . . . . . . . . . . . . . . . | $$ | . X . X O O . . . , . . . . . X . . . | $$ | . . X X O . . . . . . . . . . . . . . | $$ | . . . O . . . . . . . . . . . . . . . | $$ | . . O . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . X . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . X . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . O . . | $$ | . . . . . . . . . . . . . . . O . . . | $$ | . . . . . . . . . . . . . . . . X . . | $$ | . . . X . . . . . , X . . O . O X . . | $$ | . . . . . X . . . . . . . . . O X . . | $$ | . . . . . . . . . . . . . . . O O X . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

is Elf's choice, but it thinks that Cho Chikun's actual move is 15% better.

Enjoy!

Harleqin · **#26**

Uberdude · **#27**

Knotwilg · **#28**

Both the top left and the lower right look urgent. Let's examine the lower right first.

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

If Black solves the lower right in this active fashion, White gets good shape and sente to kill the upper left. Aji remains at ''a'' but this was a severe cutting point to start with. Having all of that resolved by a capture looks too good for White.

Passively resolving the lower right is even worse.

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

If Black passively protects the upper left, White can ignore and turn to the lower right. Black can defend in two ways.

Click Here To Show Diagram Code: [go]$$B $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . O . . . . . . . . . . . . . . . . | $$ | . O X O . . . . . . . . . . . . . . . | $$ | . X . X O O . . . , . . . . . X . . . | $$ | . . X X O . . . . . . . . . . . . . . | $$ | . . . O . . . . . . . . . . . . . . . | $$ | . . O . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . X . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . X . . | $$ | . . . . . . . . . . . . . . . a . . . | $$ | . . . . . . . . . . . . . . . 9 O 6 . | $$ | . . . . . . . . . . . . . . 0 O 5 O . | $$ | . . . . . . . . . . . . . . 8 7 X 3 4 | $$ | . . . X . . . . . , X . . O . O X . 2 | $$ | . . . . . X . . . . . . . . . O X b . | $$ | . . . . . . . . . . . . . . . O O X . | $$ | . . . . . . . . . . . . . . . . . 1 . | $$ ---------------------------------------[/go]

In this variation, White kills, A and B being miai.

Click Here To Show Diagram Code: [go]$$B $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . O . . . . . . . . . . . . . . . . | $$ | . O X O . . . . . . . . . . . . . . . | $$ | . X . X O O . . . , . . . . . X . . . | $$ | . . X X O . . . . . . . . . . . . . . | $$ | . . . O . . . . . . . . . . . . . . . | $$ | . . O . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . X . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . X . . | $$ | . . . . . . . . . . . . . . . 7 . . . | $$ | . . . . . . . . . . . . . . . 5 O 4 . | $$ | . . . . . . . . . . . . . . . O 3 2 . | $$ | . . . . . . . . . . . . . . . 6 X 1 . | $$ | . . . X . . . . . , X . . O . O X . . | $$ | . . . . . X . . . . . . . . . O X 8 . | $$ | . . . . . . . . . . . . . . . O O X . | $$ | . . . . . . . . . . . . . . . . . 2 . | $$ ---------------------------------------[/go]

The second variation is very similar.

So it looks like actively resolving the upper left is the only option

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

Besides Elf's move there's this way. Black has a nose tesuji to sacrifice.

I must say, if this weren't a problem statement from a pro game, I'd hate to be Black. Perhaps I'misreading the lower right?

Edit:

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

Maybe the plot is to cut this way. White can't bail out of this ko. If he does, there's still a ko left at A and the cut at B becomes sharper.

Beat Elf!

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