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Opening problems for AI: Problem 33
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Author:  Bill Spight [ Fri Jul 17, 2020 5:21 am ]
Post subject:  Opening problems for AI: Problem 33
Black to move.

Click Here To Show Diagram Code
[go]$$Bcm21 Black to move.
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . O . . . . |
$$ | . . . , . . . . . , . . . . . , O O . |
$$ | . . . . . . . . . . . . . . . X X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . O . . . . . |
$$ | . . . , . . . . . , . . . O X X . . . |
$$ | . . . . . . . . . . . . . X O . X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . O . O O . . |
$$ | . . X , . . . . . , . . . X . , X . . |
$$ | . . . . O . . . . . . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

In this position Black made a play that loses 18½% to par by Elf's computation, a borderine blunder, I think. Where should Black play?

As always, assume komi.

Enjoy! :)
Author:  Bill Spight [ Mon Jul 20, 2020 9:24 am ]
Post subject:  Re: Opening problems for AI: Problem 33
This seems to be a tough problem. Nobody has assayed an answer yet, anyway.

Click Here To Show Diagram Code
[go]$$Bcm21 Black to move.
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . O . . . . |
$$ | . . . , . . . . . , . . . . . , O O . |
$$ | . . . . . . . . . . . . . . . X X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . O . . . . . |
$$ | . . . , . . . . . , . . . O X X . . . |
$$ | . . . . . . . . . . . . . X O . X . . |
$$ | . . . . . . . . . . . . . . b . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . O . O O . . |
$$ | . . X , . . . . . , . . a X . , X . . |
$$ | . . . . O . . . . . . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


White has two obvious threats, the hane at a, which strengthens White's stones in the area and aims at making a framework on the bottom side, and b, which strengthens the two White stones in the center as well as the White stones in the bottom right.

The top left corner is not interesting at the moment. Which is more urgent, the center or the bottom side?
Author:  pwaldron [ Mon Jul 20, 2020 10:49 am ]
Post subject:  Re: Opening problems for AI: Problem 33
Bill Spight wrote:
Click Here To Show Diagram Code
[go]$$Bcm21 Black to move.
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . O . . . . |
$$ | . . . , . . . . . , . . . . . , O O . |
$$ | . . . . . . . . . . . . . . . X X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . O . . . . . |
$$ | . . . , . . . . . , . . . O X X . . . |
$$ | . . . . . . . . . . . . b X O . X . . |
$$ | . . . . . . . . . . . . . c a . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . d . . . . . . . . . O . O O . . |
$$ | . . X , . . . . . , . . e X . , X . . |
$$ | . . . . O . . . . . . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

Which is more urgent, the center or the bottom side?


Tough to post over the weekend.

I think the centre has to be more important than the bottom corner. 9 of Black's 10 stones are on the side, but he doesn't have a sizable territory or moyo to show for it. What he does have is groups with bases and some white stones to pressure.

Originally I thought 'a', but white will just 'b' and Black's no better of. I think 'b' or 'c' is better, to split white up. The only fly(es) in the ointment are that white has both 'd' and 'e' to look forward to, so it's tough to see how a centre fight will go. It feels like the situation demands an extension in the centre, even if I can't see the follow-up.
Author:  Bill Spight [ Mon Jul 20, 2020 10:51 am ]
Post subject:  Re: Opening problems for AI: Problem 33
The game was GoGoD 1786-03-12, between Yasui Sench Senkaku (W) and Suzuki Junsei. The problem position arose after Senchi played :w18: in the center, an overplay losing 13% to par, according to Elf. (Assuming no komi, OC. White often needs to overplay in a no komi game.)

Click Here To Show Diagram Code
[go]$$Wcm18 White overplay, mutual blind spot
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . O . . . . |
$$ | . . . , . . . . . , . . . . . , O O . |
$$ | . . . . . . . . . . . . . . . X X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . 1 . . . . . |
$$ | . . . , . . . . . , . . . O X X . . . |
$$ | . . . . . . . . . . . . . 2 O . X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . 5 3 . O O . . |
$$ | . . X , . . . . . , . . 4 X . , X . . |
$$ | . . . . O . . . . . . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

Senchi played :w18: in the center, an overplay losing 13% to par, according to Elf (assuming no komi, OC). Suzuki extended on the 4th line, certainly a reasonable looking move, but one that Elf reckons loses 18½% to par. Senchi pushed with :w22:, another bad mistake which returns the favor, losing 17%, and indicates a likely mutual blind spot.

Mainline variation for :w22:

Click Here To Show Diagram Code
[go]$$Wcm22 Sacrifice, driving tesuji
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . O . . . . |
$$ | . . . , . . . . . , . . . . . , O O . |
$$ | . . . . . . . . . . . . . . . X X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . O . . . . . |
$$ | . . . , . . . . . , . . . O X X . . . |
$$ | . . . . . . . . . . . . 1 X W . X . . |
$$ | . . . . . . . . . . . . 3 2 . . . . . |
$$ | . . . . . . . . . . . . 7 4 . . . . . |
$$ | . . . . . . . . . . . . 0 8 . . . . . |
$$ | . . . . . . . . . . . . 9 O . O O . . |
$$ | . . X , . . . . . , . . X X 5 , X . . |
$$ | . . . . O . . . . . . . . . 6 X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

:w22: and :w24: build strength in the center by sacrificing the :wc: stone. After :b25: pushes out strongly, :w26: and :w28: continue with a driving tesuji which makes :w30: urgent and strong. OC, :b31: is likewise strong, so there is that. ;)

Click Here To Show Diagram Code
[go]$$Wcm32 Mainline for :w22:, continued
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . O . . . . |
$$ | . . . 6 . . . . . , . . . . . , O O . |
$$ | . . . . . . . . . . . . . . . X X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . O . . . . . |
$$ | . . . , . . . . . , . . . O X X . . . |
$$ | . . . . . . . . . . . . O X O . X . . |
$$ | . . . . . . . . . . . . O X . . . . . |
$$ | . . . . . . . . . . . 4 O X . . . . . |
$$ | . . . . . . . . . . 3 2 X X . . . . . |
$$ | . . . 7 . . . . . . . 1 O O . O O . . |
$$ | . . X , . . . . . , . . X X O , X . . |
$$ | . . . . O . . . . . . 5 . . X X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

:w32: and :b33: reach out for air. Then White plays the hane, :w34:, with sente and stabilizes the White group with the tesuji, :w36:, at least for now. :b37: takes sente and occupies the last empty corner. Then :w38: plays the press in the bottom left.

Key point

Click Here To Show Diagram Code
[go]$$Bcm21 Exchange in the center first
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . O . . . . |
$$ | . . . , . . . . . , . . . . . , O O . |
$$ | . . . . . . . . . . . . . . . X X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . O . . . . . |
$$ | . . . , . . . . . , . . . O X X . . . |
$$ | . . . . . . . . . . . . 1 X W . X . . |
$$ | . . . . . . . . . . . . . . 2 . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . 5 4 O . O O . . |
$$ | . . X , . . . . . , . . 3 X . , X . . |
$$ | . . . . O . . . . . . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

Once you think of it, :b21: stands out as the key point for this position, it seems to me. It weakens the two center White stones and threatens to capture the :wc: stoneuniting the Black stones and making Black very strong overall. :w22: is virtually forced. Now :b23: extends on the 4th line. :) The hane at 24 is also playable for :b23:. Black answers :w24: with the hane, :b25:.

Click Here To Show Diagram Code
[go]$$Wcm26 Mainline, continued. Strong resistance
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . O . . . . |
$$ | . . . , . . . . . , . . . . . , O O . |
$$ | . . . . . . . . . . . . . . . X X 8 . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . 6 . . . . |
$$ | . . . . . . . . . . . . . . 2 1 5 . . |
$$ | . . . . . . . . . . . . . O 3 4 . . . |
$$ | . . . , . . . . . , . 7 . O X X . . . |
$$ | . . . . . . . . . . . 9 X X O . X . . |
$$ | . . . . . . . . . . . . . . O . . . . |
$$ | . . . . . . . . . . . . . . . . 0 . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . X O O . O O . . |
$$ | . . X , . . . . . , . . X X . , X . . |
$$ | . . . . O . . . . . . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

White puts up a strong resistance starting with :w26:. Black yields White strength in the center in exchange for territory on the right side.

Click Here To Show Diagram Code
[go]$$Wcm36 Mainline, continued further
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . O . . . . |
$$ | . . 3 , . . . . . , . . . . . , O O . |
$$ | . . . . . . . . . . . . . . . X X X . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . X . . . . |
$$ | . . . . . . . . . . . . . . X O O . . |
$$ | . . . . . . . . . . . . . O O X . 4 . |
$$ | . . . , . . . . . , . O . O X X . . . |
$$ | . . . . . . . . . . . O X X O . X . . |
$$ | . . . . . . . . . . . . . . O . . . . |
$$ | . . . . . . . . . . . . . . . 1 X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . X O O . O O . . |
$$ | . . X , . . . . . , 2 . X X . , X . . |
$$ | . . . . O . . . . . . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

:w36: shores up the White group, then :b37: projects strength on the bottom side and into the center. :w38: occupies the last open corner, and finally, :b39: nails down the right side.

OC, long variations should always be taken with a grain of salt, but I think that the value of the extension in the center for :b21: above the extension on the side is indicated, and that other top bots will agree. :)
Author:  Knotwilg [ Mon Jul 20, 2020 11:24 am ]
Post subject:  Re: Opening problems for AI: Problem 33
Click Here To Show Diagram Code
[go]$$Bcm21 Black to move.
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . O . . . . |
$$ | . . . , . . . . . , . . . . . , O O . |
$$ | . . . . . . . . . . . . . . . X X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . O . . . . . |
$$ | . . . , . . . . . , . . . O X X . . . |
$$ | . . . . . . . . . . . . c X O . B . . |
$$ | . . . . . . . . . . . . . d b . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . O . O O . . |
$$ | . . X , . . . . . , . . a X . , X . . |
$$ | . . . . O . . . . . . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


For me, the choice between A and B gives it away because locally B looks bad. Before looking at your suggestion I was looking at C.

B can't be good because White forces C-D and then what is the marked stone doing? Black is too strong in the area to play a soft move like B. At best he plays D directly (and then White C would surely not elicit Black B)

So it must be A. But I'm interested in comparing A to the more aggressive C.
Author:  Bill Spight [ Mon Jul 20, 2020 12:03 pm ]
Post subject:  Re: Opening problems for AI: Problem 33
Knotwilg wrote:
Click Here To Show Diagram Code
[go]$$Bcm21 Black to move.
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . O . . . . |
$$ | . . . , . . . . . , . . . . . , O O . |
$$ | . . . . . . . . . . . . . . . X X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . O . . . . . |
$$ | . . . , . . . . . , . . . O X X . . . |
$$ | . . . . . . . . . . . . c X O . B . . |
$$ | . . . . . . . . . . . . . d b . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . O . O O . . |
$$ | . . X , . . . . . , . . a X . , X . . |
$$ | . . . . O . . . . . . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


For me, the choice between A and B gives it away because locally B looks bad. Before looking at your suggestion I was looking at C.


Are you talking to me? I suggested b for White, not Black. :)
Author:  Knotwilg [ Mon Jul 20, 2020 12:44 pm ]
Post subject:  Re: Opening problems for AI: Problem 33
Quote:
Are you talking to me? I suggested b for White, not Black. :)


And so life brings that lesson taught long ago: if a smart man seems to write something dumb, read again.
Author:  Gomoto [ Mon Jul 20, 2020 1:49 pm ]
Post subject:  Re: Opening problems for AI: Problem 33
Wilcox
Author:  dhu163 [ Sat Jan 01, 2022 4:25 pm ]
Post subject:  Re: Opening problems for AI: Problem 33
Speculatively:
Current position:
1. Ooh fighting with so many weak groups. Two points stand out N9 N4 (which helps E3) O3 N6 M5 M6 L5 N5 M2 L6 K5 ... I think this fight looks ok for B as E3 seems a bit damaged and though B is thin at Q12, I'm not sure W is getting much territory from the centre fight. However W playing P8 does expose R8 aji. But the last empty corner is also looming.
2. Or N5 O6 M4 N9 O8 N8 P8 N6 D16 (W connects cleanly with reasonable good shape which seems simply better for W but B gets the corner, so perhaps ok, but I still don't like B making the Q12 attack a more serious problem.
3. Or N4 P8 N9 N5 M4 M5 (this fight also doesn't seem that easy for either side but I feel slightly better for W.

Opp to play
1. Obviously N4 as the centre fight can't be resolved with one move as both N9 and P8 are big.

Past:
1. B's fighting locally seems slightly unreasonable to me, though I feel perhaps W's move at O11 is strange when S16 is already undercutting B. I slightly prefer W here but complicated fights are always hard to judge.

Overall:
1. I still can't really decide but I feel N5 is falling into W's trap.
2. I want to play N4, though the shape feels a bit risky, as it does seem to stay ahead of W.
3. Playing in the centre to prevent Q12 seems to be B's plan, but Q12 remains and centre moves aren't often worth that much.

Check:
1. That's a crazy looking driving tesuji but it does make sense to get the key big moves at M3 and the centre isn't that weak when B is still vulnerable to Q8 (but also doesn't want to add a move there).
2. Not accurate enough to see the driving tesuji. I didn't expect W to continue the centre fight with :w22: in the ELF mainline.
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