Opening problems for AI: Problem 23

Bill Spight · Post by **Bill Spight** » Wed Jul 08, 2020 2:33 am

In this game Black made a textbook play that Elf reckons loses 15½% to par.

Click Here To Show Diagram Code: [go]$$Bcm15 Black to play $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . O . . . . . . . . . . . . . . . | $$ | . . . , O . . . . , . . . . . X . . . | $$ | . . X . O X . . . . . . . . . . . . . | $$ | . . . . X O O . . . . . . . . . . . . | $$ | . . X . X . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . O . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . O . . . | $$ | . . . X . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

Enjoy!

RobertJasiek · Post by **RobertJasiek** » Wed Jul 08, 2020 3:34 am

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

Maybe this was the textbook sequence? Black 1 at a also comes to one's mind.

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

I expect AI to play this.

Bill Spight · Post by **Bill Spight** » Wed Jul 08, 2020 3:53 am

In this series I do not generally expect the top bots to agree on the next play, but I do expect them to agree that the human play was a mistake.

pwaldron · Post by **pwaldron** » Wed Jul 08, 2020 7:24 am

Click Here To Show Diagram Code: [go]$$Bcm15 Black to play $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . O . c . . . . . . . . . . . . . | $$ | . . . , O . . . . , . . . . . X . . . | $$ | . . X . O X . . . . . . . . . . . . . | $$ | . . . . X O O . . . . . . . . . . . . | $$ | . . X . X . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . a . O . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . b . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . d . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . O . . . | $$ | . . . X . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

I've been lurking for a long time, but Bill's excellent series and ready access to a desktop brought me out.

Like Robert my first reaction was that black played 'a'. After more reflection I figured that, with the two adjacent corners for support, 'b' or 'c' was more likely. Based on Uberdude's bible, however, I'd wager that the computer would play 'd'.

Bill Spight · Post by **Bill Spight** » Wed Jul 08, 2020 11:51 am

The game is GoGoD 2003-02-19g, the 4th game of the Kisei final between O Rissei (W) and Yamashita Keigo.

Click Here To Show Diagram Code: [go]$$Bcm15 Thick and slow $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . O . a . . . . . . . . . . . . . | $$ | . . 2 , O . . . . , . . . . . X . . . | $$ | . . X . O X . . . . . . . . . . . . . | $$ | . . . . X W W . . . . . . . . . . . . | $$ | . . X . X 1 . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . O . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . O . . . | $$ | . . . X . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

Yamashita's

was new to me. When I was learning go, a was the tesuji to know, played as a sacrifice to weaken or even capture the

stones. Elf reckons that

loses 15½% to par, while a loses only 15%.

The correct answer is none of the above. O replied with

securing the corner and threatening the Black group. Elf reckons that

loses 18½% to par!

Click Here To Show Diagram Code: [go]$$Wcm16 Mainline for :w16: $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . O . . . . . . . . . . . . . . . | $$ | . . . , O . . . . , . . . . . X . . . | $$ | . . X . O X . . . . . . . . . . . . . | $$ | . . . . X O O . . . . . . . . . . . . | $$ | . . X . X X . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . W . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . b a . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . 9 . . . . . . . . . . . . . . . . | $$ | . . 1 6 . . . . . . . . . . . . . . . | $$ | . 5 4 7 3 . . . . , . . . . . O . . . | $$ | . . 8 X . 0 . . . . . . . 2 . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

approaches the bottom left corner, with

as backup.

approaches the bottom right corner. (a and b are also playable, in order of preference.)

plays the press.

does not crawl on the 3d line, but resists. An AI joseki follows.

Click Here To Show Diagram Code: [go]$$Wcm26 Mainline for :w16:, continued $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . O . . . . . . . . . . . . . . . | $$ | . . . , O . . . . , . . . . . X . . . | $$ | . . X . O X . . . . . . . . . . . . . | $$ | . . . . X O O . . . . . . . . . . . . | $$ | . . X . X X . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . O . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . O . . . . . . . . . . . . . . . . | $$ | . . O X . . . 5 7 . . . . . . . . . . | $$ | . O X O O 1 3 4 6 8 . . . . . O . . . | $$ | . . X X . X 2 . . . . . . 2 . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

White pushes to build a wall in exchange for territory.

Better play for

. Enclose the bottom left corner.

Click Here To Show Diagram Code: [go]$$Bcm15 The Black group is OK. $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . O . . . . . . . . . b . . . . . | $$ | . . . , O . . . . , . . . . . X . . . | $$ | . . X . O X . . . . . . . . . . . . . | $$ | . . . . X O O . . . . . . . . . . . . | $$ | . . X . X . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . O . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . 1 a . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . O . . . | $$ | . . . X . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

Elf's top choice is to play the large knight's enclosure of the bottom left corner, with a in second place, and certainly playable. No other play is on Elf's radar, i.e., gets more than 1.5k rollouts. I would not be too surprised if another top bot chose b. In any event, it is not urgent to do anything about the Black group in the top left corner.

Click Here To Show Diagram Code: [go]$$Bcm15 Mainline for :b15: $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . O . . . . . . 3 . . 2 . . . . . | $$ | . . . , O . . 4 . , . . . . . X . . . | $$ | . . X . O X . . . . . . . . . . . . . | $$ | . . . . X O O . . . . . . . . . a . . | $$ | . . X . X . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . O . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . 1 . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . O . . . | $$ | . . . X . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

This same position occurs in GoGoD 2000-01-29b, between Cho Chikun (W) and Kataoka Satoshi. I chose to use its variations, as they have many more rollouts (26.4k) than those in the O vs. Yamashita game.

After

encloses the bottom left corner, the top right corner becomes important. (White could also approach at a.)

approaches from the top side,

pincers, and

bolsters White's position there, in a nice flow of the stones.

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

Starting with

White boxes Black in, but then

gets to play on the top side with sente. Not that getting boxed in is good, but in exchange Black gets

and takes sente.

Knotwilg · Post by **Knotwilg** » Wed Jul 08, 2020 1:31 pm

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

I expect this is the textbook play, or maybe A. Reinforcing a 3-4 corner stone is LZ's opening gospel, so I expect B (or even C) is the better move.
White's possible move at C troubles me though. Maybe that's the textbook play?

Click Here To Show Diagram Code: [go]$$Bcm15 Black to play $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . O . . . . . . . . . . . . . . . | $$ | . . . , O . . . . , . . . . . X . . . | $$ | . . X . O X . . . . . . . . . . . . . | $$ | . . . . X O O . . . . . . . . . . . . | $$ | . . X . X . . . . . . . . . . . . . . | $$ | . . . . . 2 . . . . . . . . . . . . . | $$ | . 3 . O . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . 1. . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . O . . . | $$ | . . . X . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

Robert's suggestion for the classical move at

here looks submissive, even after the

-

exchanvge.

dhu163 · Post by **dhu163** » Fri Jun 04, 2021 10:29 am

Speculatively:

Life In 19x19

Opening problems for AI: Problem 23

Opening problems for AI: Problem 23

Re: Opening problems for AI: Problem 23

Re: Opening problems for AI: Problem 23

Re: Opening problems for AI: Problem 23

Re: Opening problems for AI: Problem 23

Re: Opening problems for AI: Problem 23

Re: Opening problems for AI: Problem 23