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 Post subject: Which side would you prefer given this start and why?
Post #1 Posted: Sun Nov 27, 2016 9:33 pm 
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I came across this opening situation today and it gave me pause for thought. I thought my friends here would enjoy having a look, then sharing which side they'd like to play and why.

Q. Black to play. Do you take Black or White given this board?
Click Here To Show Diagram Code
[go]$$B
$$ +---------------------------------------+
$$ | . . . . . . . . . . . . . . . . X . . |
$$ | . . . . . . . . . . . . . X O X . X . |
$$ | . . . O . . . . . . . . O X O O X . . |
$$ | . . . , . . . . . , . X O X X O X . . |
$$ | . . . . . . . . . . . . O . X X O O . |
$$ | . . . . . . . . . . . . . . O O . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . O . . . |
$$ | . . . X . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ +---------------------------------------+[/go]


Spoilers below:
This looks very painful for White to me, but evidently Nie Weiping felt otherwise as he seems to readily abandon those 4 white stones in the lead-up to this position. In the end the game was close: 1984-05-24 China-Japan Go Exchange, round 1
Cho Chikun 9p (Black) vs. Nie Weiping 9p (White) B+3.5 (5.5 komi)
http://www.go4go.net/go/games/sgfview/40431

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 Post subject: Re: Which side would you prefer given this start and why?
Post #2 Posted: Mon Nov 28, 2016 3:52 am 
Oza

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My first reaction is white.

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 Post subject: Re: Which side would you prefer given this start and why?
Post #3 Posted: Mon Nov 28, 2016 3:58 am 
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This early in the game I like having walls and potential to do stuff more than sitting on solid territory with no access to the center (plus black's corner is not that big), so I'd probably choose white here. What's bothering me is black's sente...

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 Post subject: Re: Which side would you prefer given this start and why?
Post #4 Posted: Mon Nov 28, 2016 4:20 am 
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Feels like a trick question heh - that the instant "oh black has killed a bunch of white stones so he's ahead!", is supposed to be wrong. But yeah, I still like black. That white influence feels very thin - can't black just cut fight? So I'd feel ahead as black and behind as white.

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 Post subject: Re: Which side would you prefer given this start and why?
Post #5 Posted: Mon Nov 28, 2016 5:37 am 
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I think the position is pretty much equal. The result in the upper right corner is a joseki so, assuming pro players, it is likely to be an equal result. Black has corner territory in the lower right and sente, possibly to approach the upper left corner or finish the lower right corner. The upper side is open at the bottom so it can easily be reduced by Black. I'd prefer, myself, to be playing Black.

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 Post subject: Re: Which side would you prefer given this start and why?
Post #6 Posted: Mon Nov 28, 2016 5:53 am 
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I got curious and got a look at the commentary of this game in Go World 37,
White 8-28. The Kajiwara joseki. Probably 70% of professionals would prefer Black's profit to White's influence, but no mere mortal can really say which side does better in the exchange.


This post by Shenoute was liked by: Drew
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 Post subject: Re: Which side would you prefer given this start and why?
Post #7 Posted: Mon Nov 28, 2016 6:55 am 
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Interesting that CS (phone version, not the strongest) prefers black here (51%, but it favours white to begin with so by this black has caught up + more), mostly because I feel it tends to go for influence over profit.

How common is this pattern, since it's a joseki?

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 Post subject: Re: Which side would you prefer given this start and why?
Post #8 Posted: Mon Nov 28, 2016 7:39 am 
Oza

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If it was white's sente then white, but with black to move not sure.

Majordomo wrote:
Feels like a trick question heh - that the instant "oh black has killed a bunch of white stones so he's ahead!", is supposed to be wrong. But yeah, I still like black. That white influence feels very thin - can't black just cut fight? So I'd feel ahead as black and behind as white.

If black immediately cuts then white gets the very pleasing 2nd line atari in sente, so I think you want to save the aji for later when a fight is profitable. Black could turn there but then you trade territory for thickness so the cut is less interesting. The peep on the right side cutting point is annoying too though (as black's corner is super-solid the endgame value of that descent is reduced, so I think you'd rather have it as solid connection, but then of course you wouldn't end up here).

Majordomo wrote:
How common is this pattern, since it's a joseki?

I don't think it's common anymore (if it ever was): I'd forgotten about this joseki and haven't seen it for years in my following of the current pro scene (I did play it on OGS once years ago). Checking ps.waltheri there are 21 hits, with black winning 14. It was most popular in the 70s to early 80s, with just 3 occurences since (2001, 2002, 2015). Here's one of those of Chang Hao going extreme moyo style against a young Gu Li:
http://ps.waltheri.net/database/game/581/
And this one from last year has the immediate cut, but that makes more sense here because of black's thickness (which I think also explains white's choice of the shoulder hit elephant jump to try to counter black's moyo):
http://ps.waltheri.net/database/game/70941/

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 Post subject: Re: Which side would you prefer given this start and why?
Post #9 Posted: Mon Nov 28, 2016 8:41 am 
Judan

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I prefer Black, but not by much. White's wall is wraparound, but definitely has chinks in its armor. The orphan Black stone still has some influence, which is what tips the balance for me.

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 Post subject: Re: Which side would you prefer given this start and why?
Post #10 Posted: Mon Nov 28, 2016 10:14 am 
Oza

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While my first thought is white, on second glance, I'd be inclined to like white more if the upper left wasn't on the awkward 3-4, allowing black a good approach there in the future. Between that, the cracks in white wall, and sente, I'm inclined to think it's fairly even.

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 Post subject: Re: Which side would you prefer given this start and why?
Post #11 Posted: Mon Nov 28, 2016 10:53 am 
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I like white.

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 Post subject: Re: Which side would you prefer given this start and why?
Post #12 Posted: Mon Nov 28, 2016 7:39 pm 
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Majordomo wrote:
Interesting that CS (phone version, not the strongest) prefers black here (51%, but it favours white to begin with so by this black has caught up + more), mostly because I feel it tends to go for influence over profit.


Your comment led me to run the same analysis with Leela. After 1mil simulations it:

* gave a 51.4% win probability to Black immediately cutting at O14 and overwhelmingly supported this variation
* gave a 50.03% win probability to Black pincering the bottom right at R7
* gave a 49.5% win probability to Black approaching the upper left at D15, which is what Cho Chikun did in the actual match

Interesting stuff!

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