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Question for Bill
http://lifein19x19.com/viewtopic.php?f=13&t=14307
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Author:  Uberdude [ Fri Jun 16, 2017 4:14 am ]
Post subject:  Re: Question for Bill

This position under discussion reminds me of a decision I faced recently in the British Challengers' league vs Andrew Kay:
I was white and black had just connected at the marked point following my invasion of the lower side (full game at http://eidogo.com/1XbHEBGLq ). The two main moves I was considering were a, a prophylactic move for my centre group, and b, solidly completing the lower side shape and in theory meaning the 3-3 is killable but with bad aji along the right side. If I don't play a move there black c is quite annoying: if I then answer at b black can comfortably live in the corner, and if I hane in the corner my 5 stones can get in trouble so I didn't actually gain much from invading the lower side. Taking gote to finish off is I believe usually considered a good result for white who gained a lot of territory, the issue is how much profit can black make from them attacking/bullying the white centre group with the thickness I have him. My initial feeling was to defend the centre group with a move at a, but after some thought I decided I didn't like that as 1) black d was still sente and I couldn't find an answer better than e which felt slack shape (and d is useful for black against white invasion at f later) and 2) wantd to get real profit at lower right. I also thought about white d or attach, but didn't like either. So in the end I played b for cash, daring black to attack, which he did at d and I answered with a fancy-pants attach. I wasn't particularly happy with the shape I got in the game, what do people think would be best or am I already in trouble? Perhaps my invasion of the lower side was not good, or move 36 (e8) should have been one line further at e9.
Click Here To Show Diagram Code
[go]$$Bc British Challengers 2017 round 5: Andrew Simons (me) 4d white vs Andrew Kay 4d black.
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . O X . . |
$$ | . . . . . . . . . O . . O . . O X . . |
$$ | . . . X . . . . . , . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . X . X . |
$$ | . . . X . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . O . . |
$$ | . . . f . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . X . d . a . , . . . . . O . . . |
$$ | . . . . . . e . . . . . . . . . . . . |
$$ | . . X . O . . . . . . . . . . . . . . |
$$ | . X . . . . O . . . . . . . . . . . . |
$$ | . X O O O . . O . . . . . . . . O . . |
$$ | . O X X . X . . . B X X . . . . . . . |
$$ | O . O X . . X . . X O X O b . O . . . |
$$ | . O O X . . . . . X O O O X . c . . . |
$$ | . O X . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

Author:  RobertJasiek [ Fri Jun 16, 2017 4:51 am ]
Post subject:  Re: Question for Bill

John Fairbairn wrote:
White lost, and there were no special tactical excitements such as kos or captures, and no mistakes were mentioned. Instead, Black said, shortly after this position, "I was confident" and White said, a little later, "I thought the game was close but I just didn't have enough."

Of course White was only a Japanese 9-dan,


If we see the game sequence, we can replace such nullarguments and failure to point out mistakes by mentioning some.

Quote:
but I expect he and Black saw the bad aji on the lower side (where White got only 24 points


24 is expected.

Quote:
and Black got a huge right corner).


Of course, Black gets something from the still weak W groups.

Author:  Bill Spight [ Fri Jun 16, 2017 6:18 am ]
Post subject:  Re: Question for Bill

John Fairbairn wrote:
Quote:
Even the roughest count tells us W leads on territory. To maintain his lead...


But White lost, and there were no special tactical excitements such as kos or captures, and no mistakes were mentioned. Instead, Black said, shortly after this position, "I was confident" and White said, a little later, "I thought the game was close but I just didn't have enough."


In another thread recently, someone asked if pros had something analogous to the value network of AlphaGo, that directly gave a precise positional evaluation, noting that the pros relied upon counting territory a lot. I think that this indicates that the answer is yes, but the evaluation is not all that precise. At least before the endgame. :)

Author:  Bill Spight [ Fri Jun 16, 2017 6:56 am ]
Post subject:  Re: Question for Bill

Uberdude wrote:
This position under discussion reminds me of a decision I faced recently in the British Challengers' league vs Andrew Kay:


Click Here To Show Diagram Code
[go]$$Bc British Challengers 2017 round 5: Andrew Simons (me) 4d white vs Andrew Kay 4d black.
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . O X . . |
$$ | . . . . . . . . . O . . O . . O X . . |
$$ | . . . X . . . . . , . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . X . X . |
$$ | . . . X . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . O . . |
$$ | . . . f . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . X . d . a . , . . . . . O . . . |
$$ | . . . . . . e . . . . . . . . . . . . |
$$ | . . X . O . . . . . . . . . . . . . . |
$$ | . X . . . . O . . . . . . . . . . . . |
$$ | . X O O O . . O . . . . . . . . O . . |
$$ | . O X X . X . . . B X X . . . . . . . |
$$ | O . O X . . X . . X O X O b . O . . . |
$$ | . O O X . . . . . X O O O X . c . . . |
$$ | . O X . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


What do you think of a move at "d"? As you say, it is a natural point for a Black attack and if White plays there, White has follow-ups on the left side.

Author:  Uberdude [ Fri Jun 16, 2017 7:55 am ]
Post subject:  Re: Question for Bill

Bill, I replied in my study journal so we don't derail this thread.

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