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 Post subject: White to play (Elf comments on pro game)
Post #1 Posted: Sun Aug 12, 2018 6:14 am 
Judan

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White's move, I numbered the last few moves to help/distract you. Where would you play?

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


This is from a pro game today (Korean baduk league I think). White is Lee Donghoon 9p, black Hong Kipyo 8p. In the game Lee made the hanging connection at g15 which surprised me as I thought the other cut was bigger and the j15/16 stones fairly light as plastered against that black wall and open at the bottom (g15 does also help a bit against black's e16 c17 combo, so it's not so much about save the 2 stones as making good shape in that area and preventing black moves around there). h13 connect was my instinct. So I checked Elf v1 and it says h13 was a whopping 37% better (giving white a good game at 59%, expects black to then sabaki stones on left; whereas g15 gives black 79% with the h13 cut. I suppose Lee thought if black cut he would force from the left and gobble up the c14 stones (but Elf still sees some aji) and deal with the black centre later. Incidentally Elf says white 1 should have been at 3 which makes a lot of sense.

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 Post subject: Re: White to play
Post #2 Posted: Sun Aug 12, 2018 8:07 am 
Judan

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My first thought:

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


But then I asked myself, where would AlphaGo play, and came up with this:

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

:lol:

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 Post subject: Re: White to play
Post #3 Posted: Sun Aug 12, 2018 8:39 am 
Lives in sente

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I also thought in the direction of W5 in Bill's "AlphaGo"-style choice. I couldn't decide exactly where to play in that area, though. I was thinking of it as being common border of two big moyos so some move that reduces one and strengthens the other would be the way to play. In retrospect, it might be too thin with the center so open.

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 Post subject: Re: White to play
Post #4 Posted: Sun Aug 12, 2018 5:01 pm 
Tengen

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My pick was F12, but I'm guessing it was too lose to actually capture

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 Post subject: Re: White to play
Post #5 Posted: Mon Aug 13, 2018 2:55 pm 
Judan

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Nice sense of the centre Bill, though with the cut present Elf thinks it's a terrible move (-32%, not quite as bad as Lee's g15). It did like that area though a few moves earlier when there wasn't a hot cut for the taking. It then expects black to play t4 and q5 as sente yose on that white group and then (or directly after more playouts) to come into the left side, interestingly at c13 rather than c14 approach.

Attachment:
Donghoon centre1.PNG
Donghoon centre1.PNG [ 709.01 KiB | Viewed 522 times ]


But rewind a few moves to before white made the t8 exchanges to help that group and Elf changes where it wants to play in the centre: either shoulder hit or attach at the top. First of all, why is the last move at j11 not so good (-6%) now? It expects black to q5, r5, t7 and then tenuki to a 2-space jump to j8 or j14. Because j11 wasn't a contact move / shoulder hit it was easier for black to tenuki as there is no strong follow-up, and because white hadn't yet made the t8 exchange black has better play against that group (not a clean kill, but a more miserable ko-life for white).
Attachment:
Donghoon centre2.PNG
Donghoon centre2.PNG [ 721.28 KiB | Viewed 522 times ]


So how about the attach? Black extends solidly into white's moyo, white plays a light knight move, black tenukis to q5 again and white extends at the top, black invades (c13 not c14 again) and white make the s9 exchange which is telling (because white hasn't made the t8 exchange it is easier to sacrifice this group and still get some value from it and the r11 stones). Note if black didn't tenuki for 4 but hane at 5 then white counter hanes and lightly jumps to k12 (or even Bill's k9!) if black solid j14 atari.

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


After 20k playouts Elf moves away from the fancy light knight move and just goes for the simple solid extend, which black counters with an impressive attachment which somehow is a good exchange before the natural (to me at least) chasing knight move.

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


Playing the knight move directly was only a little (1%) worse, but the reason for the attachment becomes clear if you let it play out the sequence: it sets up the creation of a cut and a driving tesuji to help the chase of the centre group (white's cut might seem like falling for the bait but it is a big territory, the centre won't die, and to not cut would be slack). (It takes a lot of playouts to decide the shape-making move at m11 is better than the k9 jump).
Click Here To Show Diagram Code
[go]$$Bcm8 18 at a etc.
$$ +---------------------------------------+
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . X O O . |
$$ | . . . . . O . . . X . . . O . X X O . |
$$ | . . . O . . . . . . . . . . . X O O . |
$$ | . . . . . . . . X X . . . . . X O . X |
$$ | . . . . . . e . . O O . . . X X O O . |
$$ | . . . . . 5 d X . . . . . . X . X O . |
$$ | . . . X 1 4 6 7 . . . . . . . X X X X |
$$ | . . O O 2 3 8 9 . O . b . . . . O O . |
$$ | . . . , . f 0 a . , . . . . . , . . . |
$$ | . . . . . . c . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . X . |
$$ | . . . . . . . . . . . . . . . X X O . |
$$ | . . . . . . . . . . . . . . . X O . . |
$$ | . . . . . O . . . . . . . . . . . O . |
$$ | . O O O O X . . . , X X . . . X O . . |
$$ | . X X X X O O . . O O . . . . X X O . |
$$ | . . . X . X O . . . . . . . . . . . . |
$$ | . . . . X . . . . . . . . . . . . . . |
$$ +---------------------------------------+[/go]


How about the shoulder hit? Elf's instinct is to counter with another, at g16, but then decides pushing and taking sente for q5 again is best, and we get Bill's k9 spot and then the c13 (not c14) invasion.
Click Here To Show Diagram Code
[go]$$Wc
$$ +---------------------------------------+
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . X O O . |
$$ | . . . . . O . . . X . . . O . X X O . |
$$ | . . . O . . . . . . . . . . . X O O . |
$$ | . . . . . . . . . X . . . . . X O . X |
$$ | . . . . . . . . 1 2 . . . . X X O O . |
$$ | . . 6 . . . . . . . . . . . X . X O . |
$$ | . . . . . . . . 3 . . . . . . X X X X |
$$ | . . . O . . . . . . . . . . . . O O . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . 5 . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . X . |
$$ | . . . . . . . . . . . . . . . X X O . |
$$ | . . . . . . . . . . . . . . . X O . . |
$$ | . . . . . O . . . . . . . . . 4 . O . |
$$ | . O O O O X . . . , X X . . . X O . . |
$$ | . X X X X O O . . O O . . . . X X O . |
$$ | . . . X . X O . . . . . . . . . . . . |
$$ | . . . . X . . . . . . . . . . . . . . |
$$ +---------------------------------------+[/go]


P.S. hyperpape, yes f12 too loose, doesn't stop black's sabaki on the left with b11 or c11, and doesn't defend the cut either. Elf did like to attack them at c12 earlier though instead of the j16 peep, I guess Lee didn't like that as being too small scale.


This post by Uberdude was liked by 2 people: Bill Spight, lightvector
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 Post subject: Re: White to play
Post #6 Posted: Mon Aug 13, 2018 5:55 pm 
Judan

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Uberdude wrote:
Nice sense of the centre Bill, though with the cut present Elf thinks it's a terrible move (-32%, not quite as bad as Lee's g15).

:lol:

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