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Opening problems for AI: Problem 24

https://www.lifein19x19.com/viewtopic.php?t=17626

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Opening problems for AI: Problem 24

Posted: Wed Jul 08, 2020 10:31 am
by Bill Spight
An (almost) only move problem

Edit: White to play.

Elf's top choice got 223.7k rollouts, a humungous number, while it's second choice got 4.6k rollouts. Third place got fewer than 1.5k rollouts.
Click Here To Show Diagram Code
[go]$$Wcm22 White to play
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . X . O . . . . . . . X . . . . |
$$ | . . O , . . . . . , . . . . . X X . . |
$$ | . . . . . . . . . . . . . . . O O . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . X X X . . . . . . . . . . . . . . . |
$$ | . O X O X X . . . , . . . . O , . . . |
$$ | . . O O O . X . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]
As it appears, this is an Edo Era game. But assume area scoring with 7½ komi.

Enjoy! :)

Re: Opening problems for AI: Problem 24

Posted: Wed Jul 08, 2020 1:37 pm
by Knotwilg
For those who have recently been bred with Uberdude's great rendition of LZ's opening gospel, this is a no brainer.
Corners, then corners, only then side and center.
Even more so if that corner has the 3-4 still available as here.
So invade the lower right at 3-3 or 3-4.
I choose 3-4 because it is taking Black's opposite strength into account better.

A good second is the press in the upper left, which may have been the Edo choice.

Re: Opening problems for AI: Problem 24

Posted: Wed Jul 08, 2020 2:25 pm
by Bill Spight
Knotwilg wrote:For those who have recently been bred with Uberdude's great rendition of LZ's opening gospel, this is a no brainer.
Corners, then corners, only then side and center.
Even more so if that corner has the 3-4 still available as here.
So invade the lower right at 3-3 or 3-4.
I choose 3-4 because it is taking Black's opposite strength into account better.

A good second is the press in the upper left, which may have been the Edo choice.
It's White's turn. :)

Re: Opening problems for AI: Problem 24

Posted: Wed Jul 08, 2020 2:33 pm
by Shaddy
Knotwilg wrote:For those who have recently been bred with Uberdude's great rendition of LZ's opening gospel, this is a no brainer.
Corners, then corners, only then side and center.
Even more so if that corner has the 3-4 still available as here.
So invade the lower right at 3-3 or 3-4.
I choose 3-4 because it is taking Black's opposite strength into account better.

A good second is the press in the upper left, which may have been the Edo choice.
:shock:

Re: Opening problems for AI: Problem 24

Posted: Wed Jul 08, 2020 2:34 pm
by Shaddy
if the answer isn't p15 i'm donating my dan ranks to the needy

Re: Opening problems for AI: Problem 24

Posted: Wed Jul 08, 2020 3:22 pm
by Harleqin
Extend in the top right. Don't allow the hane there.
Click Here To Show Diagram Code
[go]$$Wcm22 White to play
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . X . O . . . . . . . X . . . . |
$$ | . . O , . . . . . , . . . . . X X . . |
$$ | . . . . . . . . . . . . . . 1 O O . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . X X X . . . . . . . . . . . . . . . |
$$ | . O X O X X . . . , . . . . O , . . . |
$$ | . . O O O . X . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

Re: Opening problems for AI: Problem 24

Posted: Thu Jul 09, 2020 12:34 am
by Bill Spight
Click Here To Show Diagram Code
[go]$$Wcm22 Only move
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . X . O . . . . . . . X . . . . |
$$ | . . O , . . . . . , . . . . . X X . . |
$$ | . . . . . . . . . . . . . . c O O . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . X X X . . . . . . . . . . . . b . . |
$$ | . O X O X X . . . , . . . . O , 1 . . |
$$ | . . O O O . X . . . . . . . . . a . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]
Elf's top choice, by a huge margin in rollouts (223.7k), is enclosing the bottom right corner with :w22:. OC, Black was threatening to play there or a. I expect that other top bots will concur.

Elf's second choice is b (4.6k rollouts). No other play got as many as 1.5k rollouts. b gets only a 1% lesser winrate estimate, so it may be playable, but :w22: is much more certain.

The White stone at c is conspicuous by its absence. By today's joseki we expect it to have been played. The game was GoGoD 1620-00-00ap, between Nakamura Doseki (W) and Yasui Santetsu. Earlier in the game the play went like this.
Click Here To Show Diagram Code
[go]$$Wcm10 Sente in the top right
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . X . O . . . . . . . X . . . . |
$$ | . . O , . . . . . , . . . . . 4 2 . . |
$$ | . . . . . . . . . . . . . . a 1 3 . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X 5 X . . . . , . . . . O , b . . |
$$ | . . . . O . X . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]
:w10: played the high approach to the top right corner, and then :w14: took sente to switch to the bottom left corner, omitting the extension to a. This sente sequence in the top right cost 8½% by Elf's reckoning. For :w14: Elf already prefers b.

Mainline for :w22:
Click Here To Show Diagram Code
[go]$$Wcm22 Mainline
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . X . O . . . . . . . X . . . . |
$$ | . . O , 7 . . . . , . . . . . X X . . |
$$ | . . . . . . . . . . . . . . . O O . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . 6 . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . X X X . . . . . . . . . . . . . . . |
$$ | 4 O X O X X . . . , . . . . O , 1 . . |
$$ | . 2 O O O . X . . . . . . . . . . . . |
$$ | . 3 . . . 5 . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]
:b23: and :b25: secure eye shape for Black in the bottom left with sente. See John Fairbairn's discussions of thickness vs. thickness. :) :b27: is a high counterpincer in the top lefh, to which :w28: defends the corner. It is also a 7 space high extension from Black's strength. Before the AI era I would have considered 5 spaces the maximum for an extension, because anything longer leaves room for the opponent to make a 2 space base inside. OC, top human players used to make longer extensions before the 20th century, but that's what later textbooks came to say. :) Not that top players would not play :b27: in the 20th century, but they would not call it an extension. They would talk about making a moyo.

Doseki's play
Click Here To Show Diagram Code
[go]$$Wcm22 Left side extension
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . X . O . . . . . . . X . . . . |
$$ | . . O , . . . . . , . . . . . X X . . |
$$ | . . . . . . . . . . . . . . . O O . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . 1 . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . X X X . . . . . . . . . . . . . . . |
$$ | . O X O X X . . . , . . . . O , . . . |
$$ | . . O O O . X . . . . . . . . . a . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]
Doseki made a 4 space extension on the left side, which forestalled the Black extension cum counterpincer, leaving Black room for only a 3 space extension. However, this play loses 15% to par.

High dan amateurs would hardly make such a play these days, but it follows a sound principle. Prevent your opponent from playing where he wants to play. Black would plainly like to make a long extension from his wall, and Doseki prevented that. It's just that today, Black would like it better to invade the bottom right corner at a. :)

With the enclosure in the bottom right getting such a large number of rollouts, there is a lot in the Elf commentary to explore in subsequent variations, and I shall do so later. :)

Re: Opening problems for AI: Problem 24

Posted: Thu Jul 09, 2020 1:46 am
by Shaddy
who wants them

Re: Opening problems for AI: Problem 24

Posted: Thu Jul 09, 2020 1:59 am
by Bill Spight
Shaddy wrote:who wants them
I guess not you. ;)

Re: Opening problems for AI: Problem 24

Posted: Thu Jul 09, 2020 4:04 am
by Knotwilg
While Bill posted the solution, I was compiling this difference game to evaluate the mutual urgency.

FWIW:

Re: Opening problems for AI: Problem 24

Posted: Thu Jul 09, 2020 7:38 am
by RobertJasiek
27 is first of all "returning the pincer". Extension is a secondary purpose.

Re: Opening problems for AI: Problem 24

Posted: Thu Jul 09, 2020 8:05 am
by HermanHiddema
Shaddy wrote:who wants them
Not me. I still agree with you. I'm rather surprised the AI (and the pros, apparently) would overlook such an obvious only move :P

Re: Opening problems for AI: Problem 24

Posted: Thu Jul 09, 2020 8:37 am
by Bill Spight
Hidden for courtesy. :)
Followups to the enclosure
Click Here To Show Diagram Code
[go]$$Bcm23 Pincer against two stones
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . X . O . . . . . . . X . . . . |
$$ | . . O , 0 2 . . . , . . . . . X X . . |
$$ | . . . . . . . . . . . . . 9 7 O O . . |
$$ | . . . . . . . . . . . . . . 8 . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . 1 . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . X X X . . . . . . . . . . . . . . . |
$$ | 5 O X O X X . . . , . . . . O , W . . |
$$ | . 3 O O O . X . . . . . . . . . . . . |
$$ | . 4 . . . 6 . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]
As already indicated, 25 in the bottom left corner is the top choice after the enclosure, :wc:. But the pincer, :b23:, is the second choice. :w24: responds in the top left corner. After a pincer and tenuki, the bots generally prefer this kind of shoulder hit to the jump attachment at 32. Then Black takes his sente against the bottom left corner and comes back to the hane at :b29:. :w30: plays the counterhane and :b31: extends, as Knotwilg has indicated. Then :w32: seals in the top left corner.


Click Here To Show Diagram Code
[go]$$Wcm26 Followups after the sente in the bottom left corner
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . X . O . . . . . . . X . . . . |
$$ | . . O , . . . . . , . . . . . X X . . |
$$ | . . . . . . . . . . . . . . d O O . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . a . . . . . . . . . . . . . . . |
$$ | . . b . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . c . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . X X X . . . . . . . . . . . . . . . |
$$ | X . X O X X . . . , . . . . O , O . . |
$$ | . X O O O . X . . . . . . . . . . . . |
$$ | . O . . . 1 . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]
After :w26: Elf's top four followups are a - d, in order of preference. c we have already seen, via transposition. Now let's look at d.

Click Here To Show Diagram Code
[go]$$Bcm27 Subvariation for :b27:. hane against two stones
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . X . O . . . . . . . X . . . . |
$$ | . . O , . . . . . , . . . . . X X . . |
$$ | . . . . . . . . . . . . . 3 1 O O . . |
$$ | . . . . . . . . . . . . . . 2 . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . 4 . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . X X X . . . . . . . . . . . . . . . |
$$ | X . X O X X . . . , . . . . O , O . . |
$$ | . X O O O . X . . . . . . . . . . . . |
$$ | . O . . . O . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]
:w28: plays the counterhane, then :w30: makes a base. OC, the left side and top left corner remain unplayed, but the hane itself is not severe.

Re: Opening problems for AI: Problem 24

Posted: Thu Jul 09, 2020 8:38 am
by Bill Spight
HermanHiddema wrote:
Shaddy wrote:who wants them
Not me. I still agree with you. I'm rather surprised the AI (and the pros, apparently) would overlook such an obvious only move :P
My last post, #13, addresses that question by looking at Black's play against those two stones. :)

Re: Opening problems for AI: Problem 24

Posted: Thu Jul 09, 2020 10:50 am
by John Fairbairn
I'm rather surprised the AI (and the pros, apparently) would overlook such an obvious only move
I'm baffled by this. Please explain why it is the only move. The "obvious" I can understand. It makes a pretty shape, and all amateurs like pretty shapes. So much so that they play 90% of 90% of their games by making the "obvious" shape moves. In such games it is irrelevant who won or lost. It is a form of gambling, or staving off boredom, or escapism, or winding down before bed - or whatever. It certainly ain't trying to improve at go.

Which is the point of this series. So, why even join the thread at all if you don't want to be challenged?

FWIW I thought the "obvious" move was in the lower right. I can also explain to myself why, and prettiness doesn't come into it. The key word for me is equilibrium.
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