Evaluation of a corner sequence

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golem7
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Evaluation of a corner sequence

Post by golem7 »

Hi everyone!
I have some trouble with the evaluation of a corner sequence I never encountered before from a recent kgs game. It would be nice if some stronger players could comment on this. Although the result was not bad for me, it still somehow feels as if my opponent got away easy.

It started from here (I'm white):
Click Here To Show Diagram Code
[go]$$W Starting position.
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . , . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . 1 . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X , . . . . . , . . . . . , O . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X X . . . . . . . . . . . . . . . |
$$ | . . O X . . . . . . . . . . . . . . . |
$$ | . . O , . . . . . , . . . . . X . . . |
$$ | . . . O . O . . . . . . . X . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]
My idea was this (5 could also be at a):
Click Here To Show Diagram Code
[go]$$W The plan.
$$ ----------------
$$ . . . . . . . |
$$ . . . . . . . |
$$ . 2 . . 4 . . |
$$ . . . X . 3 . |
$$ . . . . . . . |
$$ . . 5 . 1 . . |
$$ . . . . . . . |
$$ . . . a . . . |
$$ . . . . . . . |
$$ . . . , O . . |
$$ . . . . . . . |[/go]
Instead it went like this, which felt good for w:
Click Here To Show Diagram Code
[go]$$W Black overplay?
$$ ----------------
$$ . . . . . . . |
$$ . . . . . . . |
$$ . 2 . . 7 . . |
$$ . . . X . 3 . |
$$ . . . . . . . |
$$ . . 5 . 1 . . |
$$ . . . . . . . |
$$ . . 6 . 4 . . |
$$ . . . . . . . |
$$ . . . , O . . |
$$ . . . . . . . |[/go]
Now black surprised me with 1. In retrospect, I think I should have resisted strongly with a. In the game I wanted to keep things simple but it seems white can handle the fight.
Click Here To Show Diagram Code
[go]$$B unusual...
$$ ----------------
$$ . . . . . . . |
$$ . . . . . . . |
$$ . X . . O . . |
$$ . . . X . O . |
$$ . . . . 1 . . |
$$ . . O . O a . |
$$ . . . . . . . |
$$ . . X . X . . |
$$ . . . . . . . |
$$ . . . , O . . |
$$ . . . . . . . |[/go]
continuation:
Click Here To Show Diagram Code
[go]$$B conclusion
$$ ----------------
$$ . . . . . . . |
$$ . . . . . . . |
$$ . X . . O . . |
$$ . . . X . O . |
$$ . . . 5 1 2 . |
$$ . 9 O 3 O . . |
$$ . . 7 4 6 . . |
$$ . . X 8 X . . |
$$ . . . . . . . |
$$ . . . , O . . |
$$ . . . . . . . |[/go]
The result is very peaceful (maybe too much so?). White is not small and has swallowed the marked stone while black has considerable thickness, but white has sente. I probably should have played at a next. Instead I wanted too much with b and got seperated while facing blacks aforementioned thickness. Won the fight with a bit of luck though...
Click Here To Show Diagram Code
[go]$$W Whole board end position.
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . a . . . . . . X . . O . . |
$$ | . . . O . . . . . , . . . . . X . O . |
$$ | . . . . . . . . . . . . . . . X X O . |
$$ | . . . . . . . . . . . . . X O X O . . |
$$ | . . . . . . . . . . . . . . X O O . . |
$$ | . . b . . . . . . . . . . . X O B . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X , . . . . . , . . . . . , O . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X X . . . . . . . . . . . . . . . |
$$ | . . O X . . . . . . . . . . . . . . . |
$$ | . . O , . . . . . , . . . . . X . . . |
$$ | . . . O . O . . . . . . . X . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]
What is your opinion? Is this result equal? Should white fight with a as mentioned in the 4th diagram? Are there other options for either player?
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HermanHiddema
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Re: Evaluation of a corner sequence

Post by HermanHiddema »

This is joseki:
Click Here To Show Diagram Code
[go]$$W
$$ --------------------+
$$ . . . . . . . . . . |
$$ . . . . . . . . . . |
$$ . 8 . . 4 . . 7 . . |
$$ , . . . . . X . 5 . |
$$ . . . . . . . . . . |
$$ . . . . . 3 . 1 . . |
$$ . . . . . . . . . . |
$$ . . . . . . . 2 . . |
$$ . . . . . . 6 . . . |
$$ . . . . . . , O . . |
$$ . . . . . . . . . . |[/go]
In the game sequence, you can resist like this:
Click Here To Show Diagram Code
[go]$$B resistance
$$ ----------------
$$ . . . . . . . |
$$ . . . . . . . |
$$ . X . . O . . |
$$ . . . X . O . |
$$ . . . 2 1 . . |
$$ . . O . O . . |
$$ . . . . . . . |
$$ . . X . X . . |
$$ . . . . . . . |
$$ . . . , O . . |
$$ . . . . . . . |[/go]
Now, black will have two groups to deal with.

The end result from the game is simple, and doesn't look bad for either player, IMO. Given the influence, a follow-up to neutralize the influence would indeed have been better
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flOvermind
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Re: Evaluation of a corner sequence

Post by flOvermind »

golem7 wrote:
Click Here To Show Diagram Code
[go]$$W Black overplay?
$$ ----------------
$$ . . . . . . . |
$$ . . . . . . . |
$$ . 2 . . 7 . . |
$$ . . . X . 3 . |
$$ . . . . . . . |
$$ . . 5 . 1 . . |
$$ . . . . . . . |
$$ . . 6 . 4 . . |
$$ . . . . . . . |
$$ . . . , O . . |
$$ . . . . . . . |[/go]
A little side-note:
Click Here To Show Diagram Code
[go]$$W
$$ ----------------
$$ . . . . . . . |
$$ . . . . . . . |
$$ . 2 . . 7 . . |
$$ . . . X . 3 . |
$$ . . . . c . . |
$$ . . 5 . 1 . . |
$$ . . . . . . . |
$$ . . 6 . 4 a . |
$$ . . . b . . . |
$$ . . . , W . . |
$$ . . . . . . . |[/go]
:b6: does not cut :w1: and :wc:, you can connect by attaching at 'a'. The joseki move of :b6: at 'b' does cut ;)

That doesn't really change the way you should play in this position, but it's useful to know for evaluating the position. Even if black hadn't made the mistake of :b8: at 'c', you'd still be slightly better than joseki :)
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Re: Evaluation of a corner sequence

Post by Redundant »

flOvermind wrote:
golem7 wrote:
Click Here To Show Diagram Code
[go]$$W Black overplay?
$$ ----------------
$$ . . . . . . . |
$$ . . . . . . . |
$$ . 2 . . 7 . . |
$$ . . . X . 3 . |
$$ . . . . . . . |
$$ . . 5 . 1 . . |
$$ . . . . . . . |
$$ . . 6 . 4 . . |
$$ . . . . . . . |
$$ . . . , O . . |
$$ . . . . . . . |[/go]
A little side-note:
Click Here To Show Diagram Code
[go]$$W
$$ ----------------
$$ . . . . . . . |
$$ . . . . . . . |
$$ . 2 . . 7 . . |
$$ . . . X . 3 . |
$$ . . . . c . . |
$$ . . 5 . 1 . . |
$$ . . . . . . . |
$$ . . 6 . 4 a . |
$$ . . . b . . . |
$$ . . . , W . . |
$$ . . . . . . . |[/go]
:b6: does not cut :w1: and :wc:, you can connect by attaching at 'a'. The joseki move of :b6: at 'b' does cut ;)

That doesn't really change the way you should play in this position, but it's useful to know for evaluating the position. Even if black hadn't made the mistake of :b8: at 'c', you'd still be slightly better than joseki :)
Note that the connection at a implicitly offers 5 as sacrifice.
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Re: Evaluation of a corner sequence

Post by pwaldron »

flOvermind wrote: The joseki move of :b6: at 'b' does cut ;)
If this is the joseki you're talking about, white still has a connection at 'a' if necessary. It's not usually played, but it's there.
Click Here To Show Diagram Code
[go]$$B
$$ ----------------
$$ . . . . . . . |
$$ . . . . . . . |
$$ . X . . O . . |
$$ . . . X . O . |
$$ . . . . . . . |
$$ . . O . O . . |
$$ . 5 . . . . . |
$$ . . . a X . . |
$$ . 3 . 1 . . . |
$$ . . 4 2 O . . |
$$ . . . . . . . |[/go]
golem7
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Re: Evaluation of a corner sequence

Post by golem7 »

Thanks for your thoughts so far. Indeed I know the joseki you showed, but I thought it only applies in case black has the marked stone already. Without this stone, after 8, white settles easily on the right while black's stones have no base. If black plays something on the right instead of 8, his stones on the top will come under severe attack while at the same time he will still need another move on the right side to completely subdue the white stone. That's why I thought black overplayed. Am I missing something?
Click Here To Show Diagram Code
[go]$$W
$$ --------------------+
$$ . . . . . . . . . . |
$$ . . . . . . . . . . |
$$ . 8 . . 4 . . 7 . . |
$$ , . . . . . X . 5 . |
$$ . . . . . . . . . . |
$$ . . . . . 3 . 1 . . |
$$ . . . . . . . . . . |
$$ . . . . . . . 2 . . |
$$ . . . . . . 6 . . . |
$$ . . . . . . , O . . |
$$ . . . . . . . . . . |
$$ . . . . . . . B . . |
$$ . . . . . . . . . . |[/go]
Btw, herman I never even thought about the move you suggested. Gotta study and add it to my repertoire.
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flOvermind
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Re: Evaluation of a corner sequence

Post by flOvermind »

pwaldron wrote:
flOvermind wrote: The joseki move of :b6: at 'b' does cut ;)
If this is the joseki you're talking about, white still has a connection at 'a' if necessary. It's not usually played, but it's there.
Click Here To Show Diagram Code
[go]$$B
$$ ----------------
$$ . . . . . . . |
$$ . . . . . . . |
$$ . X . . O . . |
$$ . . . X . O . |
$$ . . . . . . . |
$$ . . O . O . . |
$$ . 5 . . . . . |
$$ . . . a X . . |
$$ . 3 . 1 . . . |
$$ . . 4 2 O . . |
$$ . . . . . . . |[/go]
Interesting... Now that you post it, it's obvious, but I have always thought white is cut here ;)
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