Opening problems for AI: Problem 24

Bill Spight · Post by **Bill Spight** » Wed Jul 08, 2020 10:31 am

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!

Knotwilg · Post by **Knotwilg** » Wed Jul 08, 2020 1:37 pm

For those who have recently been bred with Uberdude's great rendition of LZ's opening gospel, this is a no brainer.

Bill Spight · Post by **Bill Spight** » Wed Jul 08, 2020 2:25 pm

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.

Shaddy · Post by **Shaddy** » Wed Jul 08, 2020 2:33 pm

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.

Shaddy · Post by **Shaddy** » Wed Jul 08, 2020 2:34 pm

Harleqin · Post by **Harleqin** » Wed Jul 08, 2020 3:22 pm

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]

Bill Spight · Post by **Bill Spight** » Thu Jul 09, 2020 12:34 am

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

. 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

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]

played the high approach to the top right corner, and then

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

Elf already prefers b.

Mainline for

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]

and

secure eye shape for Black in the bottom left with sente. See John Fairbairn's discussions of thickness vs. thickness.

is a high counterpincer in the top lefh, to which

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

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.

Shaddy · Post by **Shaddy** » Thu Jul 09, 2020 1:46 am

who wants them

Bill Spight · Post by **Bill Spight** » Thu Jul 09, 2020 1:59 am

Shaddy wrote:who wants them

I guess not you.

Knotwilg · Post by **Knotwilg** » Thu Jul 09, 2020 4:04 am

While Bill posted the solution, I was compiling this difference game to evaluate the mutual urgency.

FWIW:

RobertJasiek · Post by **RobertJasiek** » Thu Jul 09, 2020 7:38 am

27 is first of all "returning the pincer". Extension is a secondary purpose.

HermanHiddema · Post by **HermanHiddema** » Thu Jul 09, 2020 8:05 am

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

Bill Spight · Post by **Bill Spight** » Thu Jul 09, 2020 8:37 am

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,

. But the pincer,

, is the second choice.

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

.

plays the counterhane and

extends, as Knotwilg has indicated. Then

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

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]

plays the counterhane, then

makes a base. OC, the left side and top left corner remain unplayed, but the hane itself is not severe.

Bill Spight · Post by **Bill Spight** » Thu Jul 09, 2020 8:38 am

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

My last post, #13, addresses that question by looking at Black's play against those two stones.

John Fairbairn · Post by **John Fairbairn** » Thu Jul 09, 2020 10:50 am

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.

Life In 19x19

Opening problems for AI: Problem 24

Opening problems for AI: Problem 24

Re: Opening problems for AI: Problem 24

Re: Opening problems for AI: Problem 24

Re: Opening problems for AI: Problem 24

Re: Opening problems for AI: Problem 24

Re: Opening problems for AI: Problem 24

Re: Opening problems for AI: Problem 24

Re: Opening problems for AI: Problem 24

Re: Opening problems for AI: Problem 24

Re: Opening problems for AI: Problem 24

Re: Opening problems for AI: Problem 24

Re: Opening problems for AI: Problem 24

Re: Opening problems for AI: Problem 24

Re: Opening problems for AI: Problem 24

Re: Opening problems for AI: Problem 24