Life In 19x19

Posted: **Fri Oct 11, 2019 7:14 am**

I just found this and haven't analyzed it, but Elf may have missed the best play here.

Click Here To Show Diagram Code: [go]$$Wcm50 Assume 7.5 komi. White to play. $$ --------------------------------------- $$ | . . . . . . X . . . O . . . . . . . . | $$ | . O O O X X . X X O X . . O . . O . . | $$ | . X X O O . X X O O X . X . O . . . . | $$ | . X O , O X . X O , X O . O . , X . . | $$ | . X . O O O X O O . X . X X . X . . . | $$ | . X X . X O X X O . . . . . . . . . . | $$ | X . X . X O . X O . O . . . . . . . . | $$ | . X O X O O . X . . . . . . . . X . . | $$ | . O O . O X X . O O . . . . . . . . . | $$ | . O . O X O X X X X O . . . . , . . . | $$ | . X O O X O O O O X O . . . . . . . . | $$ | . X O X X X . . . O X O . . . . . . . | $$ | . X O X X . X O . O X . . . . . . . . | $$ | . . X X O X O O . O . X X . 2 . O . . | $$ | . . . . . X O X X . . X O . . . . . . | $$ | . . X , O O X 1 X , X . O . . , . . . | $$ | . . . X O . O X X . . O . . . O . . . | $$ | . . X O . O . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

After Black 151 Black has 6 White prisoners, White has 3 Black prisoners. This was a no komi game, but with Elf, let's assume 7.5 komi. Where should White play now?

Enjoy!

BTW, I am curious what other bots have to say, too.

The human play was not on Elf's radar.

Posted: **Fri Oct 11, 2019 3:18 pm**

Click Here To Show Diagram Code: [go]$$Wcm50 Assume 7.5 komi. White to play. $$ --------------------------------------- $$ | . . . . . . X . . . O . . . . . . . . | $$ | . O O O X X . X X O X . . O . . O . . | $$ | . X X O O . X X O O X . X . O . . . . | $$ | . X O , O X . X O , X O . O . , X . . | $$ | . X . O O O X O O . X . X X . X . . . | $$ | . X X . X O X X O . . . . . . . . . . | $$ | X . X . X O . X O . O . . . . . . . . | $$ | . X O X O O . X . . . . . . . . X . . | $$ | . O O . O X X . O O . . . . . . . . . | $$ | . O . O X O X X X X O . . . . , . . . | $$ | . X O O X O O O O X O . . . . . . . . | $$ | . X O X X X . . . O X O . . . . . . . | $$ | . X O X X . X O . O X . . . . . . . . | $$ | . . X X O X O O . O . X X . 2 . O . . | $$ | . . . . b X O X X . . X O . . . . . . | $$ | . . X , O O X 1 X , X . O . . , . . . | $$ | . . . X O . O X X . . O . . . O . . . | $$ | . . X O . O . a . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

If I do not change the komi of the sgf KataGo recommends a, if I change it to 7.5 it votes for b (60% white 82k playouts)

I did not trust my results and checked again with 0 komi, b (21,8 white 32k)

LZ network b (65,3% 154k)

Posted: **Tue Oct 15, 2019 7:59 am**

Just to catch up quickly, I have to run.

$$Wcm50 Assume 7.5 komi. White to play.
$$ ---------------------------------------
$$ | . . . . . . X . . . O . . . . . . . . |
$$ | . O O O X X . X X O X . . O . . O . . |
$$ | . X X O O . X X O O X . X . O . . . . |
$$ | . X O , O X . X O , X O . O . , X . . |
$$ | . X . O O O X O O . X . X X . X . . . |
$$ | . X X . X O X X O . . . . . . . . . . |
$$ | X . X . X O . X O . O . . . . . . . . |
$$ | . X O X O O . X . . . . . . . . X . . |
$$ | . O O . O X X . O O . . . . . . . . . |
$$ | . O . O X O X X X X O . . . . , . . . |
$$ | . X O O X O O O O X O . . . . . . . . |
$$ | . X O X X X . . . O X O . . . . . . . |
$$ | . X O X X . X O . O X . . . . . . . . |
$$ | . . X X O X O O . O . X X . 2 . O . . |
$$ | . . . . . X O X X . . X O . . . . . . |
$$ | . . X , O O X 1 X , X . O . . , . . . |
$$ | . . . X O . O X X . . O . . . O . . . |
$$ | . . X O . O . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------
Click Here To Show Diagram Code
[go]$$Wcm50 Assume 7.5 komi. White to play. $$ --------------------------------------- $$ | . . . . . . X . . . O . . . . . . . . | $$ | . O O O X X . X X O X . . O . . O . . | $$ | . X X O O . X X O O X . X . O . . . . | $$ | . X O , O X . X O , X O . O . , X . . | $$ | . X . O O O X O O . X . X X . X . . . | $$ | . X X . X O X X O . . . . . . . . . . | $$ | X . X . X O . X O . O . . . . . . . . | $$ | . X O X O O . X . . . . . . . . X . . | $$ | . O O . O X X . O O . . . . . . . . . | $$ | . O . O X O X X X X O . . . . , . . . | $$ | . X O O X O O O O X O . . . . . . . . | $$ | . X O X X X . . . O X O . . . . . . . | $$ | . X O X X . X O . O X . . . . . . . . | $$ | . . X X O X O O . O . X X . 2 . O . . | $$ | . . . . . X O X X . . X O . . . . . . | $$ | . . X , O O X 1 X , X . O . . , . . . | $$ | . . . X O . O X X . . O . . . O . . . | $$ | . . X O . O . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]
After Black 151 Black has 6 White prisoners, White has 3 Black prisoners. This was a no komi game, but with Elf, let's assume 7.5 komi. Where should White play now?

Click Here To Show Diagram Code: [go]$$Wcm52 Elf's play. 55.5% White winrate estimate (29.7k playouts) $$ --------------------------------------- $$ | . . . . . . X . . . O . . . . . . . . | $$ | . O O O X X . X X O X . . O . . O . . | $$ | . X X O O . X X O O X . X . O . . . . | $$ | . X O , O X . X O , X O . O . , X . . | $$ | . X . O O O X O O . X . X X . X . . . | $$ | . X X . X O X X O . . . . . . . . . . | $$ | X . X . X O . X O . O . . . . . . . . | $$ | . X O X O O . X . . . . . . . . X . . | $$ | . O O . O X X . O O . . . . . . . . . | $$ | . O . O X O X X X X O . . . . , . . . | $$ | . X O O X O O O O X O . . . . . . . . | $$ | . X O X X X . . . O X O . . . . . . . | $$ | . X O X X . X O . O X . . . . . . . . | $$ | . . X X O X O O . O . X X . X . O . . | $$ | . . . . 1 X O X X . . X O . . . . . . | $$ | . . X , O O . O X , X . O . . , . . . | $$ | . . . X O . O X X . . O . . . O . . . | $$ | . . X O . O . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

Versus Yamamoto Genkichi's play in 1803.

Click Here To Show Diagram Code: [go]$$Wcm52 Human play (0 playouts). White winrate estimate, inherited from Elf's reply, :b53:, 65.4% (14.9k playouts) $$ --------------------------------------- $$ | . . . . . . X . . . O . . . . . . . . | $$ | . O O O X X . X X O X . . O . . O . . | $$ | . X X O O 1 X X O O X . X . O . . . . | $$ | . X O , O X . X O , X O . O . , X . . | $$ | . X . O O O X O O . X . X X . X . . . | $$ | . X X . X O X X O . . . . . . . . . . | $$ | X . X . X O . X O . O . . . . . . . . | $$ | . X O X O O . X . . . . . . . . X . . | $$ | . O O . O X X . O O . . . . . . . . . | $$ | . O . O X O X X X X O . . . . , . . . | $$ | . X O O X O O O O X O . . . . . . . . | $$ | . X O X X X . . . O X O . . . . . . . | $$ | . X O X X . X O . O X . . . . . . . . | $$ | . . X X O X O O . O . X X . X . O . . | $$ | . . . . . X O X X . . X O . . . . . . | $$ | . . X , O O . O X , X . O . . 2 . . . | $$ | . . . X O . O X X . . O . . . O . . . | $$ | . . X O . O . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

When Elf sees Genkichi's play, it thinks it is 10% better than it's first choice, despite being off Elf's radar entirely.

Edit:

Elf's mainline for

.

Click Here To Show Diagram Code: [go]$$Wcm52 Elf's mainline variation $$ --------------------------------------- $$ | . . . . . . X . . . O . . . . . . . . | $$ | . O O O X X . X X O X . . O . . O . . | $$ | . X X O O 7 X X O O X . X . O . . . . | $$ | . X O , O X . X O , X O . O . , X . . | $$ | . X . O O O X O O . X . X X . X . . . | $$ | . X X . X O X X O . . . . . . . . . . | $$ | X . X 2 X O . X O . O . . . . . . . . | $$ | . X O X O O . X . . . . . . . . X . . | $$ | . O O 3 O X X . O O . . . . . . . . . | $$ | . O . O X O X X X X O . . . . , . . . | $$ | . X O O X O O O O X O . . . . . . . . | $$ | . X O X X X . . . O X O . . . . . . . | $$ | . X O X X . X O . O X . . . . . . . . | $$ | . . X X O X O O . O . X X . X . O . . | $$ | . . . . 1 X O X X . . X O . . . 6 . . | $$ | . . X , O O . O X , X . O . 4 , . . . | $$ | . . . X O . O X X . . O . . 5 O . . . | $$ | . . X O . O . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

Elf eventually gets around to Genkichi's move.

Elf's mainline reply to Genkichi's

,

Click Here To Show Diagram Code: [go]$$Wcm52 Elf's mainline reply $$ --------------------------------------- $$ | . . . . . . X . . . O . . . . . . . . | $$ | . O O O X X . X X O X . . O . . O . . | $$ | . X X O O 1 X X O O X . X . O . . . . | $$ | . X O , O X . X O , X O . O . , X . . | $$ | . X . O O O X O O . X . X X . X . . . | $$ | . X X . X O X X O . . . . . . . . . . | $$ | X . X . X O . X O . O . . . . . . . . | $$ | . X O X O O . X . . . . . . . . X . . | $$ | . O O . O X X . O O . . . . . . . . . | $$ | . O . O X O X X X X O . . . . , . . . | $$ | . X O O X O O O O X O . . . . . . . . | $$ | . X O X X X . . . O X O . . . . . . . | $$ | . X O X X . X O . O X . . . . . . . . | $$ | . . X X O X O O . O . X X . X . O . . | $$ | . . . . . X O X X . . X O . . . . . . | $$ | . . X , O O . O X , X . O . 4 2 3 . . | $$ | . . . X O . O X X . . O . . 5 O 6 . . | $$ | . . X O . O . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

Posted: **Tue Oct 15, 2019 11:04 am**

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]

Enjoy!

Posted: **Tue Oct 15, 2019 11:27 am**

Easy if your policy network is biased for cool moves

. There's a 3-4 joseki that has the same tesuji down one line that I tried to get people to play but they never cooperated.

Posted: **Sat Oct 19, 2019 8:51 am**

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? ( 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,

, 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

. If so, White fell into it with

. In any event,

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,

, 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

in two seconds flat.

It is obvious that

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

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

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

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

breaks it.

Posted: **Sat Oct 19, 2019 8:58 am**

Bill Spight wrote:I ran across this one the other day.

$$Wcm26 Black to play.
$$ ---------------------------------------
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$$ | . . . . . . . . . . . . . O O X X . . |
$$ | . . . O . . . . . , . . X X O X O . . |
$$ | . . . . . . . . . . . X O O X O X . . |
$$ | . . . . . . . . . . . O O X X O . . . |
$$ | . . . . . . . . . . . . . X O . . . . |
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$$ | . . . , . . . . . , . . . . . X . . . |
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$$ | . . . O . . . . . , . . . . . X . . . |
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$$ ---------------------------------------
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]

Posted: **Sat Oct 19, 2019 9:09 am**

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

Posted: **Wed Dec 23, 2020 11:29 am**

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.

Click Here To Show Diagram Code: [go]$$Bcm15 Mainline for W116 $$ --------------------------------------- $$ | . . . . . . . . . . . . X X X X . . . | $$ | . . . . . . . . . . . X O X O X O O . | $$ | . . . O . . X . . . X . O X O X O . O | $$ | . . O , O . . . . , . . O X O X X O . | $$ | . . X . X X . . . X X O O O O X 0 X . | $$ | . . . . . . . . . . O X X . . O X 8 9 | $$ | . . . . . . . . . . O . . X O O 6 . . | $$ | . . . . . . . . . . . O . X . O X . . | $$ | . . O . . . . . O . . . X . X O O . . | $$ | . . . , . . . . . O X O . . . 7 X 5 . | $$ | . . . . . . . . . O O X . . X 3 O . . | $$ | . . O . . . . . . X X . X X O O 4 . . | $$ | . . . . . . . X . . . . . O X O . . . | $$ | . . . O . . . X O O . X O . X 1 2 . . | $$ | . . O . O . X O X . . O . . O O . . . | $$ | . . X O O . . . X , O . X X . , O . . | $$ | . . X X O . . X . . . . . O . X O . . | $$ | . . . . X . . . . . . . . . X . X . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

Rittetsu made quite a play!

Elf reckons that Jowa made the wrong reply by not accepting the sacrifice.

The game record, with some of Elf's variations, is below.

The fraction is Black's winrate estimate (assuming komi), and the number below is the number of rollouts. Tesuji just means Good move.

Posted: **Sun Dec 27, 2020 8:50 am**

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!

Posted: **Mon Dec 28, 2020 7:29 pm**

Posted: **Tue Dec 29, 2020 3:02 am**

Posted: **Tue Dec 29, 2020 12:11 pm**

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.

Life In 19x19

Beat Elf!

Re: Beat Elf!

Re: Beat Elf!

Re: Beat Elf!

Re: Beat Elf!

Re: Beat Elf!

Re: Beat Elf!

Re: Beat Elf!

Re: Beat Elf!

Re: Beat Elf!

Re: Beat Elf!

Re: Beat Elf!

Re: Beat Elf!

Re: Beat Elf!