Exemplar of thickness

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John Fairbairn
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Exemplar of thickness

Post by John Fairbairn »

The Chinese master Zhou Heyang described Yi Ch'ang-ho's next move in the diagram below (against Ma Xiaochun) as "the exemplar of a thick move".

What was it? Black's last move is marked. If you need to count to make your assessment, White has two prisoners.

If I judge there's likely to be enough interest, I may do a thread later on what thickness really is.
Click Here To Show Diagram Code
[go]$$ Thickness question - White to play
$$ ---------------------------------------
$$ | . . . . . . . . . . O O X . . . . . . |
$$ | . . O X . . . X O . O X X O . . . . . |
$$ | . . O . . X . . X O O X X O . . . . . |
$$ | . . . O . . . X . O . O X O . X . . . |
$$ | . . . . . . . . . O . O X . . . X . . |
$$ | . . O . . . . X . . O . . X . X . . . |
$$ | . . . . . . . . . . . . . . . X O X . |
$$ | . . O . . . . . . . . . . X O O X X . |
$$ | . . . . . . . . . . . . . X . . O . . |
$$ | . . X , . . . . . , . . . . X , O . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . O X . . . |
$$ | . X X . . . . . . . . . . . O . O . . |
$$ | . O X . . X . . . . . . . O . . O . . |
$$ | . O X . . . . . . . . . X O . X O . . |
$$ | . X O O . . . . . , . . X . . X X O . |
$$ | . O O . . O . . O . X . O X X O O . . |
$$ | . . . . . . . . . . . . . . Y . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]
Click Here To Show Diagram Code
[go]$$ Thickness answer
$$ ---------------------------------------
$$ | . . . . . . . . Q . O O X . . . . . . |
$$ | . . O X . . . X O . O X X O . . . . . |
$$ | . . O . . X . . X O O X X O . . . . . |
$$ | . . . O . . . X . O . O X O . X . . . |
$$ | . . . . . . . . . O . O X . . . X . . |
$$ | . . O . . . . X . . O . . X . X . . . |
$$ | . . . . . . . . . . . . . . . X O X . |
$$ | . . O . . . . . . . . . . X O O X X . |
$$ | . . . . . . . . . . . . . X . . O . . |
$$ | . . X , . . . . . , . . . . X , O . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . O X . . . |
$$ | . X X . . . . . . . . . . . O . O . . |
$$ | . O X . . X . . . . . . . O . . O . . |
$$ | . O X . . . . . . . . . X O . X O . . |
$$ | . X O O . . . . . , . . X . . X X O . |
$$ | . O O . . O . . O . X . O X X O O . . |
$$ | . . . . . . . . . . . . . . X . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]
Not only does this move bear no resemblance to what most western amateurs think of as thickness, it doesn’t seem, at first sight, to do much more than give White two eyes. A second glance reveals that Black’s group to the left of it now becomes rather thin. But what Yi also saw, with X-ray eyes, was that it ended Black’s aspirations to make any further significant territory, as White now has no weak groups. Like a boa constrictor, White would gently squeeze the weak Black group. But unlike the hungry reptile, Yi would be satisfied with not killing the group, but just with the tasty morsels of territory he picks up on the way, quite literally the hors d’oeuvre.
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Re: Exemplar of thickness

Post by Apoah »

This is similar to some examples I have seen called thickness in reviews of my own games. I don't quite understand the principal, but effective thickness seems to apply a lot of times to a group with small life (2-4 points) but with a tiny break-out into larger territory. <---- clumsy articulation.
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RobertJasiek
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Re: Exemplar of thickness

Post by RobertJasiek »

The aspects of thickness shown by the example moves add little or no influence but are:

- eye value (in the examples: increment from fewer than two to two eyes)
- thick shape
- board division lines
- potential fighting usage

Thick corner or edge shapes facing only the edges and being without significant further impact on the middle game form a contrast by having every other aspect of thickness except for significant additional usage.
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Bill Spight
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Re: Exemplar of thickness

Post by Bill Spight »

So near, and yet so far! ;)

My sealed move:
Click Here To Show Diagram Code
[go]$$Wc
$$ ---------------------------------------
$$ | . . . . . . . 1 . . O O X . . . . . . |
$$ | . . O X . . . X O . O X X O . . . . . |
$$ | . . O . . X . . X O O X X O . . . . . |
$$ | . . . O . . . X . O . O X O . X . . . |
$$ | . . . . . . . . . O . O X . . . X . . |
$$ | . . O . . . . X . . O . . X . X . . . |
$$ | . . . . . . . . . . . . . . . X O X . |
$$ | . . O . . . . . . . . . . X O O X X . |
$$ | . . . . . . . . . . . . . X . . O . . |
$$ | . . X , . . . . . , . . . . X , O . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . O X . . . |
$$ | . X X . . . . . . . . . . . O . O . . |
$$ | . O X . . X . . . . . . . O . . O . . |
$$ | . O X . . . . . . . . . X O . X O . . |
$$ | . X O O . . . . . , . . X . . X X O . |
$$ | . O O . . O . . O . X . O X X O O . . |
$$ | . . . . . . . . . . . . . . X . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]
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— Winona Adkins

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HermanHiddema
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Re: Exemplar of thickness

Post by HermanHiddema »

Bill Spight wrote:So near, and yet so far! ;)

My sealed move:
Click Here To Show Diagram Code
[go]$$Wc
$$ ---------------------------------------
$$ | . . . . . . . 1 . . O O X . . . . . . |
$$ | . . O X . . . X O . O X X O . . . . . |
$$ | . . O . . X . . X O O X X O . . . . . |
$$ | . . . O . . . X . O . O X O . X . . . |
$$ | . . . . . . . . . O . O X . . . X . . |
$$ | . . O . . . . X . . O . . X . X . . . |
$$ | . . . . . . . . . . . . . . . X O X . |
$$ | . . O . . . . . . . . . . X O O X X . |
$$ | . . . . . . . . . . . . . X . . O . . |
$$ | . . X , . . . . . , . . . . X , O . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . O X . . . |
$$ | . X X . . . . . . . . . . . O . O . . |
$$ | . O X . . X . . . . . . . O . . O . . |
$$ | . O X . . . . . . . . . X O . X O . . |
$$ | . X O O . . . . . , . . X . . X X O . |
$$ | . O O . . O . . O . X . O X X O O . . |
$$ | . . . . . . . . . . . . . . X . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]
Exactly my move :lol:
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gowan
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Re: Exemplar of thickness

Post by gowan »

hanekomu wrote:I'm happy to say that Yi Chang-ho's move was also my first choice, because it concerns two groups that do not have definitive (two-)eye shape yet. So this move seems like the only move that concerns the stability of groups, as opposed to merely making or preventing territory.

Afterwards White can fight to the fullest extent without looking having to look back.

John - a deeper discussion about what thickness actually is would be most welcome. I remember that you already talked about this in rec.games.go in a thread about the book 実力五段囲碁読本　厚く打つ ("True-strength 5-dan Go reading book - playing thickly"). I have that book now but the Japanese text is quite over my head.

On the first page various nuances are mentioned, like 厚い ("atsui"), 厚み ("atsumi"), 厚さ ("atsusa"), 厚い形 ("atsui kei", or "atsui katachi"?), 厚い碁形 ("atsui gokei") and 厚い形勢 ("atsui keisei") - sorry I can't translate them, but that's exactly the problem: translating them all using "thickness" seems witless.

It talks about center-facing atsusa and profitable atsusa, but again - the text is way over my head. I realize that '-sa' makes an adjective into a noun, like "high" -> "height", but that's only the beginning.

Any light you could shed on this would, I'm sure, make for an interesting discussion.
Much of this discussion of "thickness" is also on several pages in Sensei's Library, starting with this: http://senseis.xmp.net/?Thickness and continuing on pages linked from there.
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RobertJasiek
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Re: Exemplar of thickness

Post by RobertJasiek »

hanekomu wrote:the hane gives Black a better chance to get eyeshape than the sagari, doesn't it?
Yes.
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