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 Post subject: How is your positional judgement? Game 19
Post #1 Posted: Sun Nov 03, 2019 8:03 am 
Honinbo

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As always, assume area scoring with 7½ pt. komi.

After :w34: the Elf GoGoD commentary gives one player a winrate estimate of 88½% with 32.2k playouts. Which player is it?

Click Here To Show Diagram Code
[go]$$Wcm34 Black to play
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O . . . . . . . . . . . . . . . . |
$$ | . . O X . . . . . . . . . O . . . . . |
$$ | . . . X . . . . . , . . . . . X . . . |
$$ | . O O . . . . . . . . . . . . . . . . |
$$ | . X O X X . . . . . . . . . . . . . . |
$$ | . . X O . . . . . . . . . . . . . . . |
$$ | . . X O O O O . . . . . . . . . . . . |
$$ | . X O X X X . . . . . . . . . . . . . |
$$ | . X O , . . . . . , . . . . . , . . . |
$$ | . X O . . . . . . . . . . . . . . . . |
$$ | . X O . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X . . . . . . . . . . . . . X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . , . . . . . O . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


Enjoy! :D

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 Post subject: Re: How is your positional judgement? Game 19
Post #2 Posted: Sun Nov 03, 2019 3:18 pm 
Lives in gote

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Agh, this looks like one where I might have to actually read out the next few moves, can't answer on general principles!

So my first impression was that black and white have two weak groups each, and black has a low position on the left, white has more centre influence, so I'd lean towards white. But black has sente and can do some damage:

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

White would like to play 'a' next (at least with respect to the centre fight), but then I think black can cut and things go badly for white. So white needs to continue with 'b' (or a point higher), black is looking a bit healthier on the left and can get ahead in the centre. Meanwhile black's top group has plenty of space around it and looks less weak the more I look at it. And white's lower left 4-4 stone isn't shining brightly. So on reflection I prefer black.

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 Post subject: Re: How is your positional judgement? Game 19
Post #3 Posted: Mon Nov 04, 2019 1:51 am 
Lives in sente
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Both players have 4-5 points on the board. White has komi, and it's Black to play. Both players have two weak groups: ordered by weakness, these groups are E11 (black), C9 (white), G12 (white), E14 (black). The group E14, despite being undercut, is not in great difficulty since it is close to the edge. The group G12 is ahead of E11 and has a supporting stone at O17. The group C9 only has 4 liberties but can run towards the edge or one of the stones D4 or Q4. Black's group E11 is the weakest one, having only 4 liberties, so Black's next move will need to defend it. Since White's G12 is ahead, the black group E14 doesn't work well with other stones Q16 or R6. So I choose white.

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 Post subject: Re: How is your positional judgement? Game 19
Post #4 Posted: Mon Nov 04, 2019 3:50 am 
Gosei
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No LZ

Click Here To Show Diagram Code
[go]$$Wcm34 Black to play
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O . . . . . . . . . . . . . . . . |
$$ | . . O B . . . . . . . . . O . . . . . |
$$ | . . . B . . . . . , . . . . . X . . . |
$$ | . O O . . . . . . . . . . . . . . . . |
$$ | . X O B B . . . . . . . . . . . . . . |
$$ | . . X @ . . . . . . . . . . . . . . . |
$$ | . . X @ @ @ @ . . . . . . . . . . . . |
$$ | . X W # # # . . . . . . . . . . . . . |
$$ | . X W , . . . . . , . . . . . , . . . |
$$ | . X W . . . . . . . . . . . . . . . . |
$$ | . X W . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X . . . . . . . . . . . . . X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . , . . . . . O . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


Let's evaluate the situation in terms of who has the heavier groups. Heavy = not strong and painful to sacrifice

1) White's squared group:
- weakness: out into the centre with 5 liberties, ahead in the running fight = "rather strong" 4/5
- importance: if captured, all Black's positions are connected = "impossible to sacrifice" 0/5
2) White's circled group
- weakness: embraced by Black, 4 liberties, some pressure to Black's side group = "weak" 2/5
- importance: if Black captures these stones, the gain is medium; WHite's corner would suffer = "rather unimportant" 4/5
3) Black's squared group
- weakness: 4 liberties, embraced by White, no pressure on the surrounding groups = "very weak" 1/5
- importance: if White connects both groups, her central strength will be formidable = "rather important" 2/5
4) Black's circled group
- weakness: lots of liberties and space to extend for eyespace = "rather strong" 4/5
- importance: if White captures this group, then the top is huge = "very important" 1/5

White 10/20, Black 8/20

It's a quantitative confirmation for my assessment that White's squared cutting stones can apply pressure on two weakish/important Black groups, while her other cutting stones are expendable.

I choose White, quite comfortably so.


LZ:



Last edited by Knotwilg on Mon Nov 04, 2019 5:37 am, edited 3 times in total.
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 Post subject: Re: How is your positional judgement? Game 19
Post #5 Posted: Mon Nov 04, 2019 4:07 am 
Lives with ko

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Is this really a positional judgement problem? Who is ahead here seems to depend only on the outcome of the left side fight.

Without deep reading, I feel that white can't save both of his group. So it depends on whether he can make enough use of the four stones as a sacrifice to kill (or get significant compensation while attacking) the top left black wall.

But it's black to play, so I don't think he will manage that, thus black is ahead.

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 Post subject: Re: How is your positional judgement? Game 19
Post #6 Posted: Sat Nov 09, 2019 3:26 pm 
Lives in gote

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Bill, do you have any further comments on this fascinating position?

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 Post subject: Re: How is your positional judgement? Game 19
Post #7 Posted: Sat Nov 09, 2019 5:06 pm 
Honinbo

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xela wrote:
Bill, do you have any further comments on this fascinating position?


Yes. :) I have slowed down to one game per week while I try to catch up with the comments. ;) It took me a long time to finish the most recent comments.

Just to give my first impressions.

It is easy for White to throw away his weak stones on the left side, but it is not easy for Black to throw away any of his weak stones, except the single stone on the left side. That makes the fight much easier for White. :)

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 Post subject: Re: How is your positional judgement? Game 19
Post #8 Posted: Fri Nov 22, 2019 11:44 am 
Honinbo

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After :w34: the Elf GoGoD commentary gives one player a winrate estimate of 88½% with 32.2k playouts. Which player is it?

It's White.

The reason that the players played the 4-4 points in the corners is not that this is from the current era, but because it is so ancient that the 4-4 opening in Japan had not yet been banished in favor of other points. It is GoGoD 1561-00-00a. Sanada Masayuki (W) vs. Sanada Nobuyuki. It may be a forgery. But I found the opening interesting. :) White won.

Click Here To Show Diagram Code
[go]$$Wcm34 Sanada Masayuki(W) - Sanada Nobuyuki
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O . . . . . . . . . . . . . . . . |
$$ | . . O X . . . . . . . . . O . . . . . |
$$ | . . . X . . . . . , . . . . . X . . . |
$$ | . O O . . . . . . . . . . . . . . . . |
$$ | . X O X X . . . . . . . . . . . . . . |
$$ | . . X O . . . . . . . . . . . . . . . |
$$ | . . X O O O O . . . . . . . . . . . . |
$$ | . X O X X X . . . . . . . . . . . . . |
$$ | . X O , . . . . . , . . . . . , . . . |
$$ | . X O . . . . . . . . . . . . . . . . |
$$ | . X O . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X . . . . . . . . . . . . . X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . , . . . . . O . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


:b31: was a blunder.

Click Here To Show Diagram Code
[go]$$Bcm31 Blunder
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O . . . . . . . . . . . . . . . . |
$$ | . . O X . . . . . . . . . O . . . . . |
$$ | . . . X . . . . . , . . . . . X . . . |
$$ | . O O . . . . . . . . . . . . . . . . |
$$ | . X O X X . . . . . . . . . . . . . . |
$$ | . . X O . . . . . . . . . . . . . . . |
$$ | . . X O O . . . . . . . . . . . . . . |
$$ | . X O X 1 . . . . . . . . . . . . . . |
$$ | . X O , . . . . . , . . . . . , . . . |
$$ | . X O . . . . . . . . . . . . . . . . |
$$ | . X O . . . . . . . . . . . . . . . . |
$$ | . . a . . . . . . . . . . . . . . . . |
$$ | . . X . . . . . . . . . . . . . X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . , . . . . . O . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


Elf says that :b31: loses 26 ½% to a.

Click Here To Show Diagram Code
[go]$$Bcm31 Elf's variation
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O . . . . . . . . . . . . . . . . |
$$ | . . O X . . . . . . . . . O . . . . . |
$$ | . . . X . 4 . 2 . , . . . . . X . . . |
$$ | . O O . . . . . . . . . . . . . . . . |
$$ | . X O X X . . . . . . . . . . . . . . |
$$ | . . X O . 3 . . . . . . . . . . . . . |
$$ | . . X O O . . . . . . . . . . . . . . |
$$ | . X O X . 5 . . . . . . . . . . . . . |
$$ | . X O , . . . . . , . . . . . , . . . |
$$ | . X O . . . . . . . . . . . . . . . . |
$$ | . X O . . . . . . . . . . . . . . . . |
$$ | . . 1 . . . . . . . . . . . . . . . . |
$$ | . . X . . . . . . . . . . . . . X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . , . . . . . O . . . |
$$ | . . . . . 6 . . . . . . . 7 . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


After :b31: :w32: attacks the weak Black stones in the top left. :b33: and :b35: skillfully dodge the attack counterattacking against White's weak stones on the left side.

More to come in a later note or notes. :)

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— Winona Adkins

Visualize whirled peas.

Everything with love. Stay safe.

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 Post subject: Re: How is your positional judgement? Game 19
Post #9 Posted: Fri Nov 22, 2019 4:20 pm 
Tengen

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Without looking at the answers.

My first thought was that black had two weak groups, so should be in trouble, but I think that any attempt to attack the lower group will let Black lean on one of the two groups below. So I think black is ok, and I think ultimately ahead. But I don't have a strong take.

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