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Let's study AlphaGo's opening book
http://lifein19x19.com/viewtopic.php?f=15&t=15310
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Author:  Uberdude [ Mon Feb 12, 2018 12:35 pm ]
Post subject:  Re: Let's study AlphaGo's opening book

Bill, we can indeed ask AlphaGo that as the position without the lower left approach-answer exchange is also in the teaching tool. It's 41% for black, so not quite as bad as with the exchange, but still pretty bad (-6% on the hanging connection version rather than -9%). So it contributes to the badness, but isn't most of it. I also wonder if part of the reason it likes the hanging connection version so much more is that it then views that approach exchange as good for black: if white then attacks the hanging connection group at k4 (a move given as balanced in the AG Lee review and the one An Youngil said was better in his review, but not in teaching tool) then there is a feeling f3 could become overconcentrated (if k4 already present and black approached I wonder if white would play a more territorially agressive move like b5 as black trying to punish that with invading the lower side is probably a bad idea with the hanging connection weak group too). I suspect worrying about playing too many stones on the lower side is a reason Lee went for the d10 instead of k4 pincer.

Edit: just to give a concrete example of how I could see f3 becoming overconcentrated. If black goes for quick life with hanging connection group (maybe not exactly now, but it's the idea) then 17-20 are locally cramped, but if you can live in sente and play a fast development it seems quite ok for black. Not sure about 21, maybe a is more AG style, is b greedy, or shimari top left?
Click Here To Show Diagram Code
[go]$$Wcm14
$$ +---------------------------------------+
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . X . . . . . . . . . . |
$$ | . . X , . . . . . , . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . 8 . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X . b . . . . . . . . . . . O . . |
$$ | . . . . . . . . . 7 . . . . . 2 3 . . |
$$ | . . a O . . . . . 1 6 . X . X , O . . |
$$ | . . . . . O . . . 5 4 . . X O O . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ +---------------------------------------+[/go]

Author:  Uberdude [ Thu Feb 15, 2018 10:47 am ]
Post subject:  Re: Let's study AlphaGo's opening book

Here's another nozomi I found. I was actually hoping to find one of my favourite openings, the black shoulder hit at j7 after white's d7 kosumi, but that's where they stop showing human moves and AG (surprise surprise!) wants to jump into 3-3, giving white sente to attack at 22. Then we get nozomi for 24, which black answers with m3 which surprised me. What's the plan if white p3? o3 clamp or p4 wedge? m3 does have the advantage of reaching out to the weak black group on the left and reduces white's scope for making eyes down there.

Click Here To Show Diagram Code
[go]$$Wcm22
$$ +---------------------------------------+
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . X . . . . . . . . . . . . . |
$$ | . . X X X O . . . . . . . . . . . . . |
$$ | . . O O O . . . . , . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . 1 . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . X . . |
$$ | . . . . . . . . . 5 . . . . . . . . . |
$$ | . . . O . X . 2 . . . . . . . . . . . |
$$ | . . O . . . . . . O . . . . . . . . . |
$$ | . . . . . . . . . . . . . . 3 . . . . |
$$ | . . . O . X . . . O . . X . . , . . . |
$$ | . . . . O X . . . . . 4 . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ +---------------------------------------+[/go]

Author:  johnsmith [ Fri Feb 16, 2018 3:04 am ]
Post subject:  Re: Let's study AlphaGo's opening book

Uberdude wrote:
answers with m3 which surprised me.
That's the only thing that surprised you? :D Nice sequence anyways.

Author:  Bill Spight [ Fri Feb 16, 2018 8:13 am ]
Post subject:  Re: Let's study AlphaGo's opening book

Uberdude wrote:
Edit: just to give a concrete example of how I could see f3 becoming overconcentrated. If black goes for quick life with hanging connection group (maybe not exactly now, but it's the idea) then 17-20 are locally cramped, but if you can live in sente and play a fast development it seems quite ok for black. Not sure about 21, maybe a is more AG style, is b greedy, or shimari top left?
Click Here To Show Diagram Code
[go]$$Wcm14
$$ +---------------------------------------+
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . X . . . . . . . . . . |
$$ | . . X , . . . . . , . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . 8 . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X . b . . . . . . . . . . . O . . |
$$ | . . . . . . . . . 7 . . . . . 2 3 . . |
$$ | . . a O . . . . . 1 6 . X . X , O . . |
$$ | . . . . . O . . . 5 4 . . X O O . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ +---------------------------------------+[/go]


Cramped vs. overconcentrated? Not much of a contest, eh? And Black lives in sente? Why does White play :w18: - :w20:, for gote, eh? After :b15: - :b17:, why not consider :w14: a success? :)

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