Opening problems for AI: Problem 44

Bill Spight · Post by **Bill Spight** » Thu Aug 13, 2020 2:22 pm

Black to play.

As always, assume komi.

Multiple choice: a, b, or c?

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

One play is Elf's top choice, one play is from the game, which loses 16% to the top choice, by Elf's reckoning, and one play is Elf's second choice, which loses 3½%, and so is probably playable.

Enjoy!

Kirby · Post by **Kirby** » Thu Aug 13, 2020 6:06 pm

Gomoto · Post by **Gomoto** » Thu Aug 13, 2020 11:42 pm

Whatever the correct move is, the follow up sequences are complicated for bot and human alike. Human intuition seems to trump low bot playouts in this position and the bot sequences are volatile. In the end Bill's advice is best for white.

Harleqin · Post by **Harleqin** » Fri Aug 14, 2020 12:57 am

Going with John's control of the diagonals, 'b' really stands out to my eyes. It even seems that White would have to defend at the top (maybe attach, hane, draw back), so one can then see whether Black needs to defend the top stones afterwards. I don't think that White can press too much around 'a', for example a keima would just be cut and fought.

So, my expectation would maybe be something like this:

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

Then maybe:

Click Here To Show Diagram Code: [go]$$Wcm20 $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . X . . . . . . . | $$ | . . . X . . . . . . X O O . O X . . . | $$ | . . . , . 2 . . . X . . . . O , X . . | $$ | . . O . 1 . . X . . . O . . . . . . . | $$ | . . . . . . . . . O . . . X . X . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . X . . . . . . . . . . . . . . . . | $$ | . . . , 3 . . . . , . . . . . , O . . | $$ | . . . O . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

Bill Spight · Post by **Bill Spight** » Fri Aug 14, 2020 2:15 am

Gomoto wrote:Whatever the correct move is, the follow up sequences are complicated for bot and human alike. Human intuition seems to trump low bot playouts in this position and the bot sequences are volatile. In the end Bill's advice is best for white.

What advice is that?

pwaldron · Post by **pwaldron** » Fri Aug 14, 2020 8:02 am

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

I'm going to pick 'b' as best, then 'c' and 'a'.

'b' highlights the defects in white's shape but just as importantly reinforces black's corner. Black's knight's move is cuttable, as we see in any number of classical games. Usefully, if white chooses to reinforce it's not automatically sente. Black may be well 'c' next.

'c' is a corner approach. Need I say more? Yay corners!

'a' looks wimpy. Black is putting a lot of stones on the top, but it's not sente and there's not much of a follow up. I'd be looking to try and kick at White first to force him to add a stone before playing 'a'. At least we might get a target to aim at.

Gomoto · Post by **Gomoto** » Fri Aug 14, 2020 6:13 pm

viewtopic.php?p=258968#p258968

Post by **Joaz Banbeck** » Fri Aug 14, 2020 10:21 pm

Move 'a' seems too close to black's other stones - a bit over-concentrated when the board is this open.
White can call C17 light and tentuki to one of several big points on the lower half of the board.

Click Here To Show Diagram Code: [go]$$Bcm15 $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . X . . . . . . X . . . O X . . . | $$ | . . . , 1 . . . . X . . . . O , X . . | $$ | . . O . . . . X . . . O . . . . . . . | $$ | . . . . . . . . . O . . . . . X . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . C . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , O . . | $$ | . . . O . . . . . . . . . . C . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

Am I worried about white taking 'a' for himself?
No, because I can play this:

Click Here To Show Diagram Code: [go]$$Wcm15 $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . X . . . . . . B . . . O X . . . | $$ | . . . 2 1 . . . . B . . . . O , X . . | $$ | . . O 3 4 . . B . . . O . . . . . . . | $$ | . . . . . . . . . O . . . . . X . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . |[/go]

...which is usually a dubious joseki, but it works here because of the black stones in the upper middle.

Move 'b' looks like aji-keshi. It forces white to strengthen a weak group.

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

Besides that, if I were going to attack the white stones in the upper right, I'd do it like this:

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

Which leaves this as the best move:

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

Uberdude · Post by **Uberdude** » Sat Aug 15, 2020 3:33 am

Black has two obvious shape problems, so first let's look at those.

The press in upper left attempts to split the two marked stones and ruin the big black territory he's trying to build there. If black submits with crawl that's good for white to bulldoze through black's potential.

Click Here To Show Diagram Code: [go]$$Wc $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . B 2 . . . . . X . . . O X . . . | $$ | . . . , 1 3 . . . X . . . . O , X . . | $$ | . . O . . . . B . . . O . . . . . . . | $$ | . . . . . . . . . O . . . . . X . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . |[/go]

So how about push and cut? Usually this is a bit of an overplay, but with the nearby support black looks fine: if white settles on the top side white will get in trouble on the left, and the black corner isn't going to die. So it's not urgent for black to fix this problem.

Click Here To Show Diagram Code: [go]$$Wc $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . 6 . . . . . . . . . . . . . . | $$ | . . . X 5 . . . . . X . . . O X . . . | $$ | . . . 2 1 . . . . X . . . . O , X . . | $$ | . . O 3 4 . . X . . . O . . . . . . . | $$ | . . . . . . . . . O . . . . . X . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . |[/go]

And even if black did play here I prefer to kick first to make White heavier so I have a target to attack if white tenukis to another big place (to avoid black fixing the problem in sente).

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

Upper right White can slice through the Knight move. Baduk doctor did a nice video on this: https://youtu.be/tnT3_J73JJE. White has the ladder so can interpose the cut of 9 to ensure 11 is sente so black can't play at 12 in sente before 13.

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

Click Here To Show Diagram Code: [go]$$Wcm11 $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . X . . . . . . X . . . O X X 4 . | $$ | . . . , . . . . . X . . a . O O X 3 . | $$ | . . O . . . . X . . . O . . . X O 7 . | $$ | . . . . . . . . . O . . . . X X O . . | $$ | . . . . . . . . . . . . . . . W X O . | $$ | . . . . . . . . . . . . . . . . X 1 . | $$ | . . . . . . . . . . . . . . . . 2 5 . | $$ | . . . , . . . . . , . . . . . , 6 . . |[/go]

Black's not collapsing, but this looks better for white. The marked white cutting stone is troublesome.

So jumping at b looks good, as this could change some of the above sequences and allow black to fight more strongly. It's sente to cut at d, so white probably answers like so.

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

If black now tenukis, say to a (or my choice locally of kick and knight move) or c, then what happens to the cut? TBC...

Click Here To Show Diagram Code: [go]$$Wcm20 $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . X . . . . . . . | $$ | . . . X . . . . . . X O O . O X 4 . . | $$ | . . . , . . . . . X . . . . O 3 X . . | $$ | . . O . . . . X . . . O . . . 2 1 . . | $$ | . . . . . . . . . O . . . X . X 5 . . | $$ | . . . . . . . . . . . . . . . 9 6 7 . | $$ | . . . . . . . . . . . . . . . . 8 . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . X . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , O . . | $$ | . . . O . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

Gomoto · Post by **Gomoto** » Sat Aug 15, 2020 5:49 am

Fatkata:

Bill Spight · Post by **Bill Spight** » Sun Aug 16, 2020 8:53 pm

I must say, I enjoy and learn from the discussions these problems evoke. Thanks to you all.

The game is GoGoD 1703-01-11b, a Castle Game between Yasui Senkaku (W) and Inoue Insetsu

Click Here To Show Diagram Code: [go]$$Bcm15 Game record $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . X . . . . . . X . . . O X . . . | $$ | . . . , 1 . . . . X . . . . O , X . . | $$ | . . O . . . . X . . . O . . . . . . . | $$ | . . . . . . . . . O . . . a 5 X . . . | $$ | . . . . . . . . . . . . . . . . 3 . . | $$ | . . . . . . . . . . . . . . . 4 2 . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , O . . | $$ | . . . O . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

Insetsu played the kosumi at a, which loses 16% to par (assuming komi). I suspect that it is a mistake with no komi, as well. You can see the attraction of forming a nice sized territory with the 5th line keima.

Elf also reckoned that Senkaku's approach,

, is a mistake. It invites Black to strengthen himself and play where he wants to play. Elf also thinks that

is a mistake by comparison with the jump to a.

Here is Elf's main variation for

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

As pwaldron points out, White likes cutting across the keima. Elf has a slight preference for

, but 18 is also good. We'll come back to that variation. OC, Black does not capture the cutting stone in this situation.

Click Here To Show Diagram Code: [go]$$Bcm25 Main variation for :w16:, continued $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . X . . . . . . X . . . O X . . . | $$ | . . . , X . . . . X . . . . O , X X . | $$ | . . O . . . . X . . . O . . . O O X . | $$ | . . . . . . . . . O . . . O O X X O . | $$ | . . . . . . . . . . . . . 6 X . . . . | $$ | . . . . . . . . . . . . . . . 5 . . . | $$ | . . . . . . . . . . . . . . 7 . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . 2 . . . . . . . . . . . . . . . . | $$ | . . . 4 . . . . . . . . . . . . . . . | $$ | . . 1 . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , O . . | $$ | . . . O . . . . . . . . . . 3 . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

approaches the bottom left corner, and White plays a one space pincer. Then Black approaches the bottom right corner and White plays kosumi against

. Next,

and

bolster Black's position in the top right.

Click Here To Show Diagram Code: [go]$$Bcm17 Variation for :b17: $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . X . . . . . . X . . . O X 3 . . | $$ | . . . , X . . . . X . . . . O 2 X . . | $$ | . . O . . . . X . . . O . . . 1 O . . | $$ | . . . . . . . . . O . . . . . X 4 . . | $$ | . . . . . . . . . . . . . . . 5 . 0 . | $$ | . . . . . . . . . . . . . . . . 7 6 . | $$ | . . . . . . . . . . . . . . . . 8 9 . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , O . . | $$ | . . . O . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

offers stiff resistance, and the play becomes complicated. Black puts pressure on the White stones on the right side.

Click Here To Show Diagram Code: [go]$$Bcm27 Variation for :b17:, continued $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . 6 5 7 . . . | $$ | . . . X . . . . . . X . . . O X X 3 . | $$ | . . . , X . . . . X . . . . O O X 2 . | $$ | . . O . . . . X . . . O . 9 . X O 4 . | $$ | . . . . . . . . . O . . . . . X O . . | $$ | . . . . . . . . . . . . . . . X 0 O . | $$ | . . . . . . . . . . . . . . . 8 B O . | $$ | . . . . . . . . . . . . . . . . O X . | $$ | . . . , . . . . . , . . . . . , . 1 . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , O . . | $$ | . . . O . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

White strengthens his stones on the right, which in turn puts pressure on the Black corner. Black bolsters the corner with a hane-and-connect. OC, Black cannot afford to connect to the atari with

, and

captures the

stone.

Click Here To Show Diagram Code: [go]$$Bcm37 Variation for :b17:, III $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . O X X . . . | $$ | . . . X . . . . . . X . . . O X X X . | $$ | . . . , X . . . . X . . 1 . O O X O . | $$ | . . O . . . . X . . . O . X . X O O . | $$ | . . . . . . . . . O . . . 3 . X O . . | $$ | . . . . . . . . . . . . . . . X O O . | $$ | . . . . . . . . . . . . . 2 . O . O . | $$ | . . . . . . . . . . . . . . . . O X . | $$ | . . . , . . . . . , . . . . . , . X . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . 4 . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . 5 . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , O . . | $$ | . . . O . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

goes after the four White stones on the top side.

plays kikashi, and then

lays claim to the right side. IMO,

is nicely placed.

Now

approaches the bottom left corner.

Elf's second choice

Click Here To Show Diagram Code: [go]$$Bcm15 Approach the bottom left corner $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . X . . . . . . X . . . O X . . . | $$ | . . . , . . . . . X . . . . O , X . . | $$ | . . O . . . . X . . . O . . . . . . . | $$ | . . . . . . . . . O . . . . . X . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . 1 . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , O . . | $$ | . . . O . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

This approach is probably playable. It got so few rollouts, however, that Elf does not even show White's response. With so few rollouts we cannot be sure of its winrate estimate.

Elf's top choice

Click Here To Show Diagram Code: [go]$$Bcm15 One space jump $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . X . . . . . . X a . . O X . . . | $$ | . . 5 , . 7 . . . X . . 2 . O , X . . | $$ | . . O 6 . . . X . . . O . . . . . . . | $$ | . . . . . . . . . O . . . 1 . X . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . 4 . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . b . . . . . . . . . . . . . . . . | $$ | . . 3 . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , O . . | $$ | . . . O . . . . . . . . . 8 . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

Elf prefers the jump to

, which strengthens Black in the top right and threatens to cut White in two.

connects the White stones. Elf thinks that the jump attachment at a is also good. FatKata prefers to enclose the bottom left corner at b. After

, Black approaches the bottom left corner. White now makes a base in the top left with

, then

plays the kick and

lays claim to the top side, as pwaldron and Uberdude suggest.

Then

encloses the bottom right corner.

Next let's look at the jump attachment for

Click Here To Show Diagram Code: [go]$$Wcm16 Jump attachment $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . 2 . . . . . . . | $$ | . . . X . . . . . . X 1 3 . O X . . . | $$ | . . . , . . . . . X . . . . O , X . . | $$ | . . O . . . . X . 6 5 O . . . . . . . | $$ | . . . . . . . . . O 4 . . X . X . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . a . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , O . . | $$ | . . . O . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

replies with the 2d line hane.

extends, but enclosing the bottom left corner at a is also good.

now cuts across Black's keima.

Click Here To Show Diagram Code: [go]$$Wcm22 Driving tesuji $$ --------------------------------------- $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . X . . . . . . . | $$ | . . . X . . . . . . X O O . O X . . . | $$ | . . . , . . . . . X . . . . O , X . . | $$ | . . O . . . . X . X O O . . . . 9 . . | $$ | . . . . . . . . . O X 2 3 X . X . . . | $$ | . . . . . . . . . . 1 4 5 . . . . . . | $$ | . . . . . . . . . . . 6 7 . . . . . . | $$ | . . . . . . . . . . . 8 . . . . . . . | $$ | . . . , . . . . . , . . . . . , . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . , . . . . . , . . . . . , O . . | $$ | . . . O . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ | . . . . . . . . . . . . . . . . . . . | $$ ---------------------------------------[/go]

now initiates a driving tesuji which pushes out into the center. Black is strengthened in the center, but

is a severe cut across the Black keima in the top right.

The one space jump jumped out at me.

And the kosumi in the top left just seemed passive and pedestrian. If it realistically threatened the White approach stone, that would be a different matter.

BTW, after the one space jump I like the jump attachment to induce the 2d line hane with sente, and then enclosing the bottom left corner.

dhu163 · Post by **dhu163** » Mon Dec 26, 2022 9:28 am

Life In 19x19

Opening problems for AI: Problem 44

Opening problems for AI: Problem 44

Re: Opening problems for AI: Problem 44

Re: Opening problems for AI: Problem 44

Re: Opening problems for AI: Problem 44

Re: Opening problems for AI: Problem 44

Re: Opening problems for AI: Problem 44

Re: Opening problems for AI: Problem 44

Re: Opening problems for AI: Problem 44

Re: Opening problems for AI: Problem 44

Re: Opening problems for AI: Problem 44

Re: Opening problems for AI: Problem 44

Re: Opening problems for AI: Problem 44