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 Post subject: questions on a position
Post #1 Posted: Mon Sep 18, 2017 6:33 pm 
Honinbo

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KGS: Kirby
Tygem: 커비라고해
There's a position from the train like a pro series, which I'm curious about.


Click Here To Show Diagram Code
[go]$$Bcm1
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O X . . O . . . . . . . X . . . . |
$$ | . . O X . . . . . , . . . . . , X . . |
$$ | . . O X . . . . . . . . . . . . . . . |
$$ | . . . B . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X . . . . . . . . . . . . . . . . |
$$ | . X O O . . . . . . . . . . . . . . . |
$$ | . X X O . . . . . , . . . . . O . . . |
$$ | . X O . . O . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ----------------------------------------[/go]


The question is how to respond as white. In thinking about the problem, I actually did consider the move that was given as the answer:
Click Here To Show Diagram Code
[go]$$Bcm1
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O X . . O . . . . . . . X . . . . |
$$ | . . O X . . . . . , . . . . . , X . . |
$$ | . . O X . . . . . . . . . . . . . . . |
$$ | . . . X . . . . . . . . . . . . . . . |
$$ | . W . . . . . . . . . . . . . . . . . |
$$ | . . O . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X . . . . . . . . . . . . . . . . |
$$ | . X O O . . . . . . . . . . . . . . . |
$$ | . X X O . . . . . , . . . . . O . . . |
$$ | . X O . . O . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ----------------------------------------[/go]


But it was more of selecting the move because it felt right, and not for any other reason. But the problem I had with this move was this sequence:
Click Here To Show Diagram Code
[go]$$Bcm1
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O X . . O . . . . . . . X . . . . |
$$ | . . O X . . . . . , . . . . . , X . . |
$$ | . . O X . . . . . . . . . . . . . . . |
$$ | . 8 7 X . . . . . . . . . . . . . . . |
$$ | . W 9 4 6 . . . . . . . . . . . . . . |
$$ | . . O 1 5 . . . . . . . . . . . . . . |
$$ | . . 3 2 . . . . . . . . . . . . . . . |
$$ | . . X , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X . . . . . . . . . . . . . . . . |
$$ | . X O O . . . . . . . . . . . . . . . |
$$ | . X X O . . . . . , . . . . . O . . . |
$$ | . X O . . O . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ----------------------------------------[/go]


Now white's stones are cut off.

Given this line of reasoning, I selected the simpler move here:
Click Here To Show Diagram Code
[go]$$Bcm1
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O X . . O . . . . . . . X . . . . |
$$ | . . O X . . . . . , . . . . . , X . . |
$$ | . . O X . . . . . . . . . . . . . . . |
$$ | . . W X . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X . . . . . . . . . . . . . . . . |
$$ | . X O O . . . . . . . . . . . . . . . |
$$ | . X X O . . . . . , . . . . . O . . . |
$$ | . X O . . O . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ----------------------------------------[/go]


I had the suspicion it might be wrong since it was so simple. But it seems to do better with black's cover:
Click Here To Show Diagram Code
[go]$$Bcm1
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O X . . O . . . . . . . X . . . . |
$$ | . . O X . . . . . , . . . . . , X . . |
$$ | . . O X . . . . . . . . . . . . . . . |
$$ | . . W X . . . . . . . . . . . . . . . |
$$ | . . . 4 6 . . . . . . . . . . . . . . |
$$ | . . O 1 5 . . . . . . . . . . . . . . |
$$ | . . 3 2 . . . . . . . . . . . . . . . |
$$ | . . X , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X . . . . . . . . . . . . . . . . |
$$ | . X O O . . . . . . . . . . . . . . . |
$$ | . X X O . . . . . , . . . . . O . . . |
$$ | . X O . . O . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ----------------------------------------[/go]


Black's shape is destroyed.

So I liked that one better.

Back to the solution shape:
Click Here To Show Diagram Code
[go]$$Bcm1
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O X . . O . . . . . . . X . . . . |
$$ | . . O X . . . . . , . . . . . , X . . |
$$ | . . O X . . . . . . . . . . . . . . . |
$$ | . . . X . . . . . . . . . . . . . . . |
$$ | . W . . . . . . . . . . . . . . . . . |
$$ | . . O . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X . . . . . . . . . . . . . . . . |
$$ | . X O O . . . . . . . . . . . . . . . |
$$ | . X X O . . . . . , . . . . . O . . . |
$$ | . X O . . O . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ----------------------------------------[/go]


I'm trying to think of why this might be better. Some thoughts:
Click Here To Show Diagram Code
[go]$$Bcm1
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O X . . O . . . . . . . X . . . . |
$$ | . . O X . . . . . , . . . . . , X . . |
$$ | . . O X . . . . . . . . . . . . . . . |
$$ | . . O X . . . . . . . . . . . . . . . |
$$ | . a . . . . . . . . . . . . . . . . . |
$$ | . . O . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X . . . . . . . . . . . . . . . . |
$$ | . X O O . . . . . . . . . . . . . . . |
$$ | . X X O . . . . . , . . . . . O . . . |
$$ | . X O . . O . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ----------------------------------------[/go]


There's kind of a weak-ish point at 'a', but it doesn't work right now. Further, black will probably continue to break white's shape:
Click Here To Show Diagram Code
[go]$$Bcm1
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O X . . O . . . . . . . X . . . . |
$$ | . . O X . . . . . , . . . . . , X . . |
$$ | . . O X . . . . . . . . . . . . . . . |
$$ | . . O X . . . . . . . . . . . . . . . |
$$ | . . . 1 . . . . . . . . . . . . . . . |
$$ | . 2 O . . . . . . . . . . . . . . . . |
$$ | . . . . 3 . . . . . . . . . . . . . . |
$$ | . . X , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X . . . . . . . . . . . . . . . . |
$$ | . X O O . . . . . . . . . . . . . . . |
$$ | . X X O . . . . . , . . . . . O . . . |
$$ | . X O . . O . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ----------------------------------------[/go]


Another thought is that the solution move might be better for endgame:
Click Here To Show Diagram Code
[go]$$Bcm1
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O X . . O . . . . . . . X . . . . |
$$ | . . O X . . . . . , . . . . . , X . . |
$$ | . . O X . . . . . . . . . . . . . . . |
$$ | . . . B . . . . . . . . . . . . . . . |
$$ | . O . . . . . . . . . . . . . . . . . |
$$ | . . O . . . . . . . . . . . . . . . . |
$$ | . b . . . . . . . . . . . . . . . . . |
$$ | . . X , . . . . . , . . . . . , . . . |
$$ | . c . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X . . . . . . . . . . . . . . . . |
$$ | . X O O . . . . . . . . . . . . . . . |
$$ | . X X O . . . . . , . . . . . O . . . |
$$ | . X O . . O . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ----------------------------------------[/go]


Offering a followup at 'b', or maybe even at 'c'. But isn't the situation about whether or not black can cover more important than endgame right now?


Basically, I don't understand why the suggested move is better. And the only reason it came to mind when I was looking at the problem was because I saw pros play something similar in some kind of shape like that. But I don't really get it at a practical level in this position.

Any thoughts?

_________________
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 Post subject: Re: questions on a position
Post #2 Posted: Mon Sep 18, 2017 7:59 pm 
Lives in sente
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Kirby wrote:
But it was more of selecting the move because it felt right, and not for any other reason. But the problem I had with this move was this sequence:
Click Here To Show Diagram Code
[go]$$Bcm1
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O X . . O . . . . . . . X . . . . |
$$ | . . O X . . . . . , . . . . . , X . . |
$$ | . . O X . . . . . . . . . . . . . . . |
$$ | . 8 7 X . . . . . . . . . . . . . . . |
$$ | . W 9 4 6 . . . . . . . . . . . . . . |
$$ | . . O 1 5 . . . . . . . . . . . . . . |
$$ | . . 3 2 . . . . . . . . . . . . . . . |
$$ | . . X , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X . . . . . . . . . . . . . . . . |
$$ | . X O O . . . . . . . . . . . . . . . |
$$ | . X X O . . . . . , . . . . . O . . . |
$$ | . X O . . O . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ----------------------------------------[/go]



Is that the best sequence? What about:

Click Here To Show Diagram Code
[go]$$Bcm1
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O X . . O . . . . . . . X . . . . |
$$ | . . O X . . . . . , . . . . . , X . . |
$$ | . . O X . . . . . . . . . . . . . . . |
$$ | . . . X . . . . . . . . . . . . . . . |
$$ | . W . . . . . . . . . . . . . . . . . |
$$ | . . O 1 . . . . . . . . . . . . . . . |
$$ | . . 3 2 4 . . . . . . . . . . . . . . |
$$ | . . X , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X . . . . . . . . . . . . . . . . |
$$ | . X O O . . . . . . . . . . . . . . . |
$$ | . X X O . . . . . , . . . . . O . . . |
$$ | . X O . . O . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ----------------------------------------[/go]


Kirby wrote:
Given this line of reasoning, I selected the simpler move here:
Click Here To Show Diagram Code
[go]$$Bcm1
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O X . . O . . . . . . . X . . . . |
$$ | . . O X . . . . . , . . . . . , X . . |
$$ | . . O X . . . . . . . . . . . . . . . |
$$ | . . W X . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X . . . . . . . . . . . . . . . . |
$$ | . X O O . . . . . . . . . . . . . . . |
$$ | . X X O . . . . . , . . . . . O . . . |
$$ | . X O . . O . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ----------------------------------------[/go]



One problem with that sequence is the issue of A after this exchange (i.e. black doesn't have to play the way you showed).

Click Here To Show Diagram Code
[go]$$Bcm1
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O X . . O . . . . . . . X . . . . |
$$ | . . O X . . . . . , . . . . . , X . . |
$$ | . . O X . . . . . . . . . . . . . . . |
$$ | . . W X . . . . . . . . . . . . . . . |
$$ | . a . 1 . . . . . . . . . . . . . . . |
$$ | . . O 2 . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X . . . . . . . . . . . . . . . . |
$$ | . X O O . . . . . . . . . . . . . . . |
$$ | . X X O . . . . . , . . . . . O . . . |
$$ | . X O . . O . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ----------------------------------------[/go]

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 Post subject: Re: questions on a position
Post #3 Posted: Mon Sep 18, 2017 8:17 pm 
Honinbo

Posts: 9545
Liked others: 1600
Was liked: 1711
KGS: Kirby
Tygem: 커비라고해
Thanks for the first sequence:
Click Here To Show Diagram Code
[go]$$Bcm1
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O X . . O . . . . . . . X . . . . |
$$ | . . O X . . . . . , . . . . . , X . . |
$$ | . . O X . . . . . . . . . . . . . . . |
$$ | . . . X . . . . . . . . . . . . . . . |
$$ | . W . . . . . . . . . . . . . . . . . |
$$ | . . O 1 . . . . . . . . . . . . . . . |
$$ | . . 3 2 4 . . . . . . . . . . . . . . |
$$ | . . X , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X . . . . . . . . . . . . . . . . |
$$ | . X O O . . . . . . . . . . . . . . . |
$$ | . X X O . . . . . , . . . . . O . . . |
$$ | . X O . . O . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ----------------------------------------[/go]


Of course, that makes sense. Somehow, I automatically read "breaking through", since I compared it to the variation I had in mind. Regarding your second comment, do you mean white doesn't have to play that way? Still seems OK for white to me.

My question still remains about why the given move is better than the simple one, specifically. Is it because black has the forcing move here?
Click Here To Show Diagram Code
[go]$$Bcm1
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O X . . O . . . . . . . X . . . . |
$$ | . . O X . . . . . , . . . . . , X . . |
$$ | . . O X . . . . . . . . . . . . . . . |
$$ | . . O X . . . . . . . . . . . . . . . |
$$ | . . . B . . . . . . . . . . . . . . . |
$$ | . a O b . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X . . . . . . . . . . . . . . . . |
$$ | . X O O . . . . . . . . . . . . . . . |
$$ | . X X O . . . . . , . . . . . O . . . |
$$ | . X O . . O . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ----------------------------------------[/go]


If followed by 'a' or 'b', above, is this that bad for white?

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be immersed

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 Post subject: Re: questions on a position
Post #4 Posted: Mon Sep 18, 2017 8:53 pm 
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Kirby wrote:
Click Here To Show Diagram Code
[go]$$Bcm1
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O X . . O . . . . . . . X . . . . |
$$ | . . O X . . . . . , . . . . . , X . . |
$$ | . . O X . . . . . . . . . . . . . . . |
$$ | . . O X . . . . . . . . . . . . . . . |
$$ | . . . B . . . . . . . . . . . . . . . |
$$ | . a O b . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X . . . . . . . . . . . . . . . . |
$$ | . X O O . . . . . . . . . . . . . . . |
$$ | . X X O . . . . . , . . . . . O . . . |
$$ | . X O . . O . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ----------------------------------------[/go]


If followed by 'a' or 'b', above, is this that bad for white?


Given this particular board, I think a and b are problematic for white. b seems kind of useless, given how strong black is in lower left, as well as leaving the awful peep aji behind, while a will leave black very strong (assuming black follows with something like E11). I will definitely prefer black in this position. Whether this thinking applies more generally is hard to say.

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 Post subject: Re: questions on a position
Post #5 Posted: Mon Sep 18, 2017 9:58 pm 
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One possible thing for white to focus on is to keep the four black stones in the upper-left weak and profit from harassing them. From this point of view, I (kind of) can see why the kosumi at A13 may work better, since it doesn't force black to respond. But this is more of an after-thought, if I look at this position as a problem and try to reverse-engineer the reasons for this solution :-)

If I look at this as a game: the board is very open on the right, lower and upper sides, while the left side is pretty boring. So what I would like to do as white is to take sente in the upper-left and play some large point such as K17, or R10.

R10 is just large, while K17 seems "hot" since it involves unsettled groups. For that reason I feel the upper side is more important...

Also - any idea how was this position created? I am trying to figure out the order of moves in the upper-left and I cannot...


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 Post subject: Re: questions on a position
Post #6 Posted: Mon Sep 18, 2017 10:17 pm 
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alphaville wrote:
One possible thing for white to focus on is to keep the four black stones in the upper-left weak and profit from harassing them.


Somehow, this resonates with me a little bit. I guess the solution move keeps black weak, whereas C14 lets black get strong.

alphaville wrote:
Also - any idea how was this position created? I am trying to figure out the order of moves in the upper-left and I cannot...


I don't know how the position was created. The book has various problem positions. Maybe it was from somebody's game that the author knew about.

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Post #7 Posted: Mon Sep 18, 2017 10:20 pm 
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I found the game. The game is from 2003: Lee Changho 9d vs. Luo Xihe 9d.

Here it is:


I guess white's pressure on the black stones does turn out useful.

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Post #8 Posted: Mon Sep 18, 2017 10:41 pm 
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Oh, cool, it's from a real game - and a very interesting one!

Looking at the game, I can do some more reverse-engineering: B13 seems to be the most resilient move after black plays C18-E18 combination, since if white played instead at C14 (or C13), he would have to worry about black pushing at C14 and cutting.

So white is also clearly looking at the C8 invasion already when he played B13, and trying to help black as little as possible.

All looks good - but I doubt I will find this kind of fancy move in my own games :-)

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Post #9 Posted: Tue Sep 19, 2017 12:28 am 
Oza

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Click Here To Show Diagram Code
[go]$$Bcm1
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O X . . O . . . . . . . X . . . . |
$$ | . . O X . . . . . , . . . . . , X . . |
$$ | . . O X . . . . . . . . . . . . . . . |
$$ | . . . X . . . . . . . . . . . . . . . |
$$ | . W . . . . . . . . . . . . . . . . . |
$$ | . . O 1 . . . . . . . . . . . . . . . |
$$ | . . 3 2 4 . . . . . . . . . . . . . . |
$$ | . . X , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X . . . . . . . . . . . . . . . . |
$$ | . X O O . . . . . . . . . . . . . . . |
$$ | . X X O . . . . . , . . . . . O . . . |
$$ | . X O . . O . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ----------------------------------------[/go]


Apart from this being a plausible way for White to respond, why have you assumed (a) Black will play 1 - he didn't in the game - and (b) that White will answer it? White can consider playing where Black actually played, i.e. on the upper side.

It's interesting that your intuition threw up the right initial defence for White. These low moves generally seem to trouble amateurs. A variant on the theme is when there is a fourth line vs third line series of pushes going along and the third line pro player makes a second-line slide where amateurs typically make a third-line jump, as in Chitoku-Chiteki, 1813:



But having said all that, the upper left position has occurred elsewhere in pro play. Yasui Santetsu played the narabi at C7 in 1620. Iwamoto chose the kosumi as here in 1953 and, just after Yi Chang-ho aboye, Yamada Kimio chose the nobi at C6. So the right move is not cut-and-dried. The overall position is bound to be a factor, but the local choice may also be a matter of style.


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Post #10 Posted: Tue Sep 19, 2017 6:29 am 
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This move helps Black the least out of the plausible moves.

Click Here To Show Diagram Code
[go]$$Bcm1
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O X . . O . . . . . . . X . . . . |
$$ | . . O X . . . . . , . . . . . , X . . |
$$ | . . O X . . . . . . . . . . . . . . . |
$$ | . . c B . . . . . . . . . . . . . . . |
$$ | . b a . . . . . . . . . . . . . . . . |
$$ | . . O . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X . . . . . . . . . . . . . . . . |
$$ | . X O O . . . . . . . . . . . . . . . |
$$ | . X X O . . . . . , . . . . . O . . . |
$$ | . X O . . O . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ----------------------------------------[/go]

My first thought was at 'a', because the kosumi is not really in my "vocabulary". This leaves push and cut at 'b', and Black will not be in real danger after that. I considered 'c', but after Black extends, White doesn't have a good next move locally, and Black can connect to the bottom left. Kosumi at 'b' is nice because now it's Black who doesn't have a good next move locally, and he has to struggle a bit to live.


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 Post subject: Re: questions on a position
Post #11 Posted: Tue Sep 19, 2017 10:02 pm 
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John Fairbairn wrote:
Apart from this being a plausible way for White to respond, why have you assumed (a) Black will play 1 - he didn't in the game - and (b) that White will answer it? White can consider playing where Black actually played, i.e. on the upper side.


I would say that I didn't necessarily think that black would play there. Specifically, I was trying to compare the relative merits of the 3rd line push vs. the 2nd line move. It seemed that the 3rd line push had a benefit: black definitely cannot block white off with 1.

That being said, since black isn't interested in playing there to begin with, maybe that says something about my logic.

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Post #12 Posted: Tue Sep 19, 2017 10:04 pm 
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alphaville wrote:
Oh, cool, it's from a real game - and a very interesting one!

Looking at the game, I can do some more reverse-engineering: B13 seems to be the most resilient move after black plays C18-E18 combination, since if white played instead at C14 (or C13), he would have to worry about black pushing at C14 and cutting.

So white is also clearly looking at the C8 invasion already when he played B13, and trying to help black as little as possible.

All looks good - but I doubt I will find this kind of fancy move in my own games :-)


Seems logical, looking at the way the played.

Maybe my problem is that I'm thinking too locally, trying to find a reason that 2nd line is better than 3rd, or whatever. Maybe it's better to read out the sequence I want to play, and see which local move will serve me best 10 moves down the line.

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Post #13 Posted: Tue Sep 19, 2017 10:06 pm 
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Shaddy wrote:
This move helps Black the least out of the plausible moves.

Click Here To Show Diagram Code
[go]$$Bcm1
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O X . . O . . . . . . . X . . . . |
$$ | . . O X . . . . . , . . . . . , X . . |
$$ | . . O X . . . . . . . . . . . . . . . |
$$ | . . c B . . . . . . . . . . . . . . . |
$$ | . b a . . . . . . . . . . . . . . . . |
$$ | . . O . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X . . . . . . . . . . . . . . . . |
$$ | . X O O . . . . . . . . . . . . . . . |
$$ | . X X O . . . . . , . . . . . O . . . |
$$ | . X O . . O . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ----------------------------------------[/go]

My first thought was at 'a', because the kosumi is not really in my "vocabulary". This leaves push and cut at 'b', and Black will not be in real danger after that. I considered 'c', but after Black extends, White doesn't have a good next move locally, and Black can connect to the bottom left. Kosumi at 'b' is nice because now it's Black who doesn't have a good next move locally, and he has to struggle a bit to live.


Yeah, 'a' was something that came to mind, too. It feels like something someone around my level would play :-p

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Post #14 Posted: Wed Sep 20, 2017 5:02 am 
Judan

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I think they key point here is you need to consider the pros and cons in the local continuations if black and white play first, and then look at the global position to see, given the expected flow of the game, who is likely to play first locally and who that's good for.

So my first thought is I don't want to keep on pushing from behind as that increases the strength of the black wall (which looking globally is not strong, white has a pincer stone so likely wants to attack it), but jump ahead. So there's the 3rd line move which has this obvious weakness (maybe don't need to play 3-4, but if you don't maybe white would capture on other side and let you into corner which is a big loss, but I did it to make threat on 3 stones obvious):

Click Here To Show Diagram Code
[go]$$Bcm1
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . 4 3 . . . . . . . . . . . . . . . . |
$$ | . . O X . . O . . . . . . . X . . . . |
$$ | . . O X . . . . . , . . . . . , X . . |
$$ | . 8 O X . . . . . . . . . . . . . . . |
$$ | . 6 5 1 . . . . . . . . . . . . . . . |
$$ | . 7 2 . . . . . . . . . . . . . . . . |
$$ | . . O . . . . . . . . . . . . . . . . |
$$ | . a . . . . . . . . . . . . . . . . . |
$$ | . . X , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X . . . . . . . . . . . . . . . . |
$$ | . X O O . . . . . . . . . . . . . . . |
$$ | . X X O . . . . . , . . . . . O . . . |
$$ | . X O . . O . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ----------------------------------------[/go]


So this means white's one point jump out to the centre (if white is next to play in the area) has a classic cutting tesuji weakness (maybe 2 at 6 directly more stylish, but W might resist). Also a above is sente, but you don't want to play it too early as it fixes the jump weakness, but might be relevant for c8 gap:

Click Here To Show Diagram Code
[go]$$Wcm1
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . O X . . . . . . . . . . . . . . . . |
$$ | . . O X . . O . . . . . . . X . . . . |
$$ | . . O X . . . . . , . . . . . , X . . |
$$ | . O O X . . . . . . . . . . . . . . . |
$$ | . O X X . . . . . . . . . . . . . . . |
$$ | 7 X O 8 . . . . . . . . . . . . . . . |
$$ | 5 2 O 6 1 . . . . . . . . . . . . . . |
$$ | . 3 4 . . . . . . . . . . . . . . . . |
$$ | . . X , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X . . . . . . . . . . . . . . . . |
$$ | . X O O . . . . . . . . . . . . . . . |
$$ | . X X O . . . . . , . . . . . O . . . |
$$ | . X O . . O . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ----------------------------------------[/go]


Compare this to jumping following the kosumi, black's typical attempt to cut the shape is peep and cut at waist, but it doesn't work as white's corner stick is now 4 not 3 stones long (and white is safe even if black 2 is connected):

Click Here To Show Diagram Code
[go]$$Wcm1
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . 3 2 . . . . . . . . . . . . . . . . |
$$ | . . O X . . O . . . . . . . X . . . . |
$$ | . . O X . . . . . , . . . . . , X . . |
$$ | . . O X . . . . . . . . . . . . . . . |
$$ | . 6 7 X . . . . . . . . . . . . . . . |
$$ | . O 8 4 . . . . . . . . . . . . . . . |
$$ | . 9 O 5 1 . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X . . . . . . . . . . . . . . . . |
$$ | . X O O . . . . . . . . . . . . . . . |
$$ | . X X O . . . . . , . . . . . O . . . |
$$ | . X O . . O . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ----------------------------------------[/go]


So if white wants to play next in the area to jump out, the kosumi is better (though there's also e13 knight jump to consider which stops the tesuji of diagram 2, but leaves another cut).

How about if black first? If black tries to cover the 3rd line move on 4th line (5th at a is flimsy shape with an obvious gap) white can maybe push out though black has that cutting tesuji on 2nd line to make liberty troubles (maybe corner hane first) but white might allow the cut and develop the outside group:

Click Here To Show Diagram Code
[go]$$Bcm1
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O X . . O . . . . . . . X . . . . |
$$ | . . O X . . . . . , . . . . . , X . . |
$$ | . . O X . . . . . . . . . . . . . . . |
$$ | . 4 3 X . . . . . . . . . . . . . . . |
$$ | . 5 O 2 . . . . . . . . . . . . . . . |
$$ | . . O 1 a . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X . . . . . . . . . . . . . . . . |
$$ | . X O O . . . . . . . . . . . . . . . |
$$ | . X X O . . . . . , . . . . . O . . . |
$$ | . X O . . O . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ----------------------------------------[/go]


Or maybe white would look at the whole board and tenuki, extending that lone stone on the top is clearly an important place. Maybe black spends another move to connect, and white extends again? Or 4 somewhere else like lower left or right side?

Click Here To Show Diagram Code
[go]$$Bcm1
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O X . . O . . 2 . . 4 . X . . . . |
$$ | . . O X . . . . . , . . . . . , X . . |
$$ | . . O X . . . . . . . . . . . . . . . |
$$ | . . . X . . . . . . . . . . . . . . . |
$$ | . . O 3 . . . . . . . . . . . . . . . |
$$ | . . O 1 . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X . . . . . . . . . . . . . . . . |
$$ | . X O O . . . . . . . . . . . . . . . |
$$ | . X X O . . . . . , . . . . . O . . . |
$$ | . X O . . O . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ----------------------------------------[/go]


Compare if the same idea happens with kosumi (black's reinforcement with 3 is a bit different):

Click Here To Show Diagram Code
[go]$$Bcm1
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O X . . O . . 2 . . 4 . X . . . . |
$$ | . . O X . . . . . , . . . . . , X . . |
$$ | . . O X . . . . . . . . . . . . . . . |
$$ | . . . X . . . . . . . . . . . . . . . |
$$ | . O . . . . . . . . . . . . . . . . . |
$$ | . . O 1 . . . . . . . . . . . . . . . |
$$ | . . 3 . . . . . . . . . . . . . . . . |
$$ | . . X , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X . . . . . . . . . . . . . . . . |
$$ | . X O O . . . . . . . . . . . . . . . |
$$ | . X X O . . . . . , . . . . . O . . . |
$$ | . X O . . O . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ----------------------------------------[/go]


How to judge these 2 results? I think they are both globally good for white who got to settle nicely on the top side. How about the left side shape? c10 got an extra stone in the 2nd, so maybe c8 area stronger, but also the wall is not so thick and has a cut/peep. Top one the black wall is thicker and has double hane if white tries to crawl along left side, so is probably a bit worse for territory but better thickness to top side but not left side.

So I think the key point is white is happy with either of these results (though perhaps one subtly better), so black won't allow that and will pincer on the top side, which means the fact kosumi has better shape for white to come out later is most important. Also from an efficiency standpoint c13 makes c12 look a bit odd.


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 Post subject: Re: questions on a position
Post #15 Posted: Fri Sep 22, 2017 9:45 pm 
Honinbo

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Uberdude wrote:
I think they key point here is you need to consider the pros and cons in the local continuations if black and white play first, and then look at the global position to see, given the expected flow of the game, who is likely to play first locally and who that's good for.


That's a pretty tall order :-) I appreciate your analysis. I might go as far as to evaluate some pros and cons of a local continuation with me playing first, but I rarely think of all combinations of who is playing first locally vs. the global position, the flow of the game, and who is likely to play first.

I guess I must be too lazy.


Uberdude wrote:
So I think the key point is white is happy with either of these results (though perhaps one subtly better), so black won't allow that and will pincer on the top side, which means the fact kosumi has better shape for white to come out later is most important. Also from an efficiency standpoint c13 makes c12 look a bit odd.


Nice thought process to get to that conclusion. Seems a bit daunting to me. Maybe this problem is just a bit too difficult for me to assess properly.

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 Post subject: Re: questions on a position
Post #16 Posted: Fri Sep 22, 2017 11:18 pm 
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Maybe just conclude that the connection on the 2nd line is more "shapely" than the third line, and make that your first choice move when assessing options. This choice comes up often, as the two space jump on the third line is an extremely common move.

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 Post subject: Re: questions on a position
Post #17 Posted: Sat Sep 23, 2017 1:16 am 
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Here is a related position I came across yesterday: go to move 51.



I have noticed that in such instances the pro typically plays the triangled move, leaving two cuts behind, whereas the typical amateur tends to opt for the safer aji of A. That aji is quite strong, actually, as after a cut at A White has a standard but good attachment at B, and that was even played in this game.

It seems very rare to see a comment on this choice and I have always assumed it's down to pros taking the trouble to "read" deeper whereas we tend to play with much less time and so take the safer options. I say "read" in quotes because it's usually not possible (as here) to read out specific lines, but there seems to be rather more envisioning of the future than just evaluating the position. (Incidentally that's one reason I don't have much truck with the school that makes a binary distinction between "you first evaluate a position" and "you must read out the next play." There is a hazy in-between.)

Anyhoo, I was surprised to see a comment on this move by the player, and he said that the triangled move at A would leave better aji for later but then the relationship with the area above would become "very different."

Unfortunately that's all he said, and it leaves some things hanging dreadfully: what are the relationships above, and why "very" different as opposed to different, and why no mention of the side relationships?

On the other hand, reading between the lines, we can infer from the lack of self-reproach in the comment that he was happy with his choice (and Black did win). There may be clues in the final position, but frankly, to me, Back's choice just seemed to help White get a big centre more easily. One reason for such moves in many positions is to take a liberty away from the opponent, but here move 51 still leaves White in a "five alive" liberty situation with no Black stones remotely in the offing, so I assume the choice was 100% strategic.

So what do you think Black saw in the position that made him choose 51 over A?

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 Post subject: Re: questions on a position
Post #18 Posted: Sat Sep 23, 2017 7:20 am 
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I have no idea, John. P2 seems better to me, too, but I must be missing something.

Locally, the move in the game "feels good" since it takes away liberty and is closer to the center. But as you point out, from the aji, black was sealed in anyway.

Maybe he had the option of giving up the corner? But he didn't.

I don't know.

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 Post subject: Re: questions on a position
Post #19 Posted: Sat Sep 23, 2017 7:43 am 
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I don't know the answer, but a few thoughts:

1) White's cut is nice for the outside, but it gives up some points.
2) Black is taking a liberty, which while not important now can easily become important later.
3) Black is locally alive, but White's hane in the corner may become sente later if he plays the "safe" move. If he plays as in the game and White cuts, there will never be any issues with living.

When I've played with this position before, I noticed that none of Black's potential moves are really satisfying: the second line move "feels" slow, the move played here leaves the cut, connecting in the corner leaves a soft outside.

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 Post subject: Re: questions on a position
Post #20 Posted: Sat Sep 23, 2017 9:18 am 
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John Fairbairn wrote:
I have noticed that in such instances the pro typically plays the triangled move, leaving two cuts behind, whereas the typical amateur tends to opt for the safer aji of A. That aji is quite strong, actually, as after a cut at A White has a standard but good attachment at B, and that was even played in this game.


I looked up the position in the lower-right corner (searching a 9x9 sized corner).
The 3rd line connection doesn't even appear once, it is mostly the 2nd line one (first choice), then tiger-mouth on the inside (2nd option).

Only when searching on 7x7 I get one game where the 3rd line move (like in the game you posted) appears, but there is an enemy stone nearby (and the game is quite advanced, as in many moves played) which may have influenced the choice.
(Obviously, I don't have the game you posted in my database).

So, what you call "the typical amateur move" is also the "typical pro move" in this case :-)

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