Opening problems for AI: Problem 7

Bill Spight · Post by **Bill Spight** » Wed Jun 17, 2020 11:50 am

Here is another surprisingly early move by Takagawa that Elf really, really does not like. It comes from GoGoD 1952-01-09a, vs. Kitani. Takagawa was on his way to his first Honinbo title.

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

The bottom left corner is pretty much a dead giveaway that Kitani was playing White. It is one of his trademark joseki.

There are many possibilities, so different AI may well have different preferences. But I doubt if any of them likes Takagawa's play.

Bill Spight · Post by **Bill Spight** » Wed Jun 17, 2020 12:14 pm

Click Here To Show Diagram Code: [go]$$Bcm13 Standard extension $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . O . O . . . . . . . . . . . . . | $$ | . . O , . . . . . , . . . . . X . . . | $$ | . . X X . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . 1 . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . O , X . . . . , . . . . . X . . . | $$ | . . . . O X . . . . . . . . . . . . . | $$ | . . . . O . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

is a standard, textbook play, but Elf reckons that it loses 21½% to a play against the bottom left corner.

Click Here To Show Diagram Code: [go]$$Bcm13 Bottom side moyo $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . O . O . . . . . . . . . . . . . | $$ | . . O , . . . . . , . . . . . X . . . | $$ | . . X X . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . 4 . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . 3 . . . . . . . . . . . . . . | $$ | . . O 2 X . . . . , . . . . . X . . . | $$ | . . . . O X . . . . . . 5 . . . . . . | $$ | . . . . O 1 . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

In Elf's mainline variation,

blocks White's group from the bottom side, and after White solidifies the corner,

stakes out the bottom side. It's an early moyo, but Elf still likes it.

I think that this line illustrates that the Black extension on the left side is just not big enough, by comparison.

Click Here To Show Diagram Code: [go]$$Wcm14 Elf's reply $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . O . O . . . . . . . . . . 5 . . | $$ | . . O , . . . . . , . . . . . X . . . | $$ | . . X X . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . X . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . O 2 X 1 . . . , . . . . . X . . . | $$ | . . 3 . O X . . . . . . . 4 . . . . . | $$ | . . . . O . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

In the actual game, Kitani played

at 15, but Elf prefers the cut by 13%.

still encloses the bottom right corner, but without forming a framework.

RobertJasiek · Post by **RobertJasiek** » Wed Jun 17, 2020 1:55 pm

"standard, textbook play" says nothing about whether it is a locally or globally considered play. The extension is mainly locally motivated.

My applicable global textbook-like advice is: defend the weakest important group first. The lower black group was weaker than the left black group.

Uberdude · Post by **Uberdude** » Thu Jun 18, 2020 2:08 am

A year ago Jean-Sébastien Lechasseur found a very normal opening position in which LeelaZero with 2 million playouts preferred Kitani's exotic joseki:

https://www.facebook.com/groups/go.igo. ... 599366514/

Pics copied for those who avoid facebook:

: lzkitani.jpg (92.74 KiB) Viewed 7905 times

mainline:

: lzkitani2.jpg (83.41 KiB) Viewed 7905 times

Bill Spight · Post by **Bill Spight** » Thu Jun 18, 2020 3:47 am

Thanks, Uberdude.

Interesting that White's reply to the Black sagari is to block on the 2d line. The main replies are the stand on the 5-5 or the hanging connection on the 5-6, but Kitani also shows the block in his book, Watashi no Go, vol. 2.

Harleqin · Post by **Harleqin** » Fri Jun 19, 2020 8:56 am

“Watashi no Go” is quite a title… ^^

dhu163 · Post by **dhu163** » Fri Jun 04, 2021 9:56 am

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