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 Post subject: Handling groups in the center - KataGo's vs Shodan vision
Post #1 Posted: Sat Nov 06, 2021 4:26 pm 
Oza
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When analyzing my games with KataGo, one of the patterns is that KataGo can handle weak groups in the center by maintaining an overall pressure on the surrounding positions which is non-trivial. In this game, at move 89 it gives me a lead by komi. At move 104 I'm trailing by komi, at 114 I'm already 40 behind and by 134 I'm 80 behind, due to a large dragon ending up with only one eye, while it's not so easy to see with my shodan eyes where and why I have made capital mistakes.

I invite you to read below a sgf analysis starting at 89.

Although stronger players will probably recognize these mistakes, we may also consider earlier, smaller mistakes or even choices which turned the game into such a fragile position for White.

For these you can return to 38, 44, 60 and 62.



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 Post subject: Re: Handling groups in the center - KataGo's vs Shodan visio
Post #2 Posted: Sun Nov 07, 2021 1:00 am 
Gosei
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Reminds me of this post: https://lifein19x19.com/viewtopic.php?p=262899#p262899

JF wrote:
To put this in stark terms, and allowing myself a smidgeon of hyperbole to make a point, if you imagine ten groups on the board early in a typical game and ask amateurs which ones are weak, most would say one or two. A higher dan would say 3 or 4 and (as an expression of his fuzzy suspicions) "maybe a couple more". A good professional would say 9. A bot might say "10 at the moment, 12 in a few moves time."

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 Post subject: Re: Handling groups in the center - KataGo's vs Shodan visio
Post #3 Posted: Sun Nov 07, 2021 4:08 am 
Oza

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I haven't changed my thinking on that, and have in fact tried to move on from there. I haven't come to firm conclusions, but an idea I am wrestling with at the moment is how we define the centre.

I believe most players, perhaps even pros, think of the centre as that space in the middle of the board. I have a sense that AI is inviting us to see it differently, and certainly not as an empty space. My feeling now is that AI "sees" an area in which weak groups exist and, because they are weak, there is an inter-relationship between them all. By their nature, what we call the corners and sides (having board edges in their support) tend not to be inherently weak and so do not have weak groups within their (fuzzy) boundaries. Groups outside this area, on the other hand, are predisposed to be weak. Rather than considering this outside area to be the empty centre (as we do), I think the bots effectively "see" instead a lerger "weak-group domain", which may occupy all or part of the geographical centre, and may even also include portions of the sides and even corners.

Within this weak-group domain a bot is able to exploit the inter-relationships in a way that is mostly beyond us, except for utterly simple cases such as ladder-breakers.

However, I see hope in the old Chinese concept of zhaoying, or call & response. Having been brought up on the local tale of Grace Darling, a fantastically brave lighthouse-keeper's daughter, I prefer to think of this concept in terms of lighthouses. A move in the centre (or as I would now more strictly say, in the weak-group domain, i.e. the perilous ocean) that shines out and offers succour to storm-lashed boats in the offing can have inestimable value. Of course it works differently in old Chinese go, because such moves have value not just in saving groups but in connecting them, which pays off handsomely in terms of avoiding group tax.

Since immersing myself in Chinese go for the Museum of Go Theory project, I have kept a weather eye open for such moves in modern go. They do occur (with less value perhaps, because of the absence of group tax, but still a significant value) but they tend not to be mentioned, and if they are, they are talked about in vague and inconsistent ways - e.g. "lends a helping hand" or "looks towards his group below." There is no concept word, no equivalent to zhaoying.

My intuition is that there should be, and that it should imply (as zhaoying does) that there is a weak-group domain. Indeed, as I write that, it occurs to me that the word for 'centre' is rare in old Chinese commentaries, and I will now pause for a moment to check....

Ta da! In my corpus of old Chinese go texts, zhaoying occurs a whopping 33 times. The word for centre appears zero times. There is no word for weak-group domain either, of course, but that is implied in the call & response meaning.

As I said, my thoughts are still in a formative stage, but already I can see value in thinking about, say, shoulder hits in terms of how they interact with a WGD rather than with just the centre. I have in mind, in particular, Go Seigen's comment that usually, when a shoulder hit is answered with a push up, the best follow up is usually not a heavy nobi (making a potentially weak group), but a jump. And if to comes to that, thinking of a jump as a barrier, in the Chinese way, rather than as a jump, has value, too. But, of course, learning to identify a WGD allows you also to make repairs, or prophylactic moves. Such moves feature heavily in AI and pro play, and often not at all in amateur play. When amateurs do play them, it seems to me it's often a case of monkey see, monkey do rather than with true understanding (as with josekis). And when there is some understanding, it is limited to one weak group rather than the weak-group domain. There is no call & response - just a response.


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 Post subject: Re: Handling groups in the center - KataGo's vs Shodan visio
Post #4 Posted: Sun Nov 07, 2021 5:18 am 
Dies with sente

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A very nice lesson which could almost fit with the extended whole-game examples in the Ishida Akira/James Davies book 'Attack and Defence". I hope you consider making this a series.

I think a six group game is hard to play ( as the proverb warns:"Five Groups Might Live But The Sixth Will Die")- so you're setting yourself a hard challenge in this game (or your opponent skilfully encouraged you into it).

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 Post subject: Re: Handling groups in the center - KataGo's vs Shodan visio
Post #5 Posted: Sun Nov 07, 2021 5:21 pm 
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The reading in such games is very difficult and really needs to be done far in advance. Some of the sequences from KataGo shown look like white is lucking into something that works. Maybe the lesson from KataGo is "do not try this at home"?

The small lead that white has in exchange for having to defend the two groups is probably just too small. If you can pull the same thing off with a lot larger margin it would be much easier to handle these groups. At least that is my opinion. The bots seem to handle any adverse situation somehow without affecting the score but the rest of us just can't do the same.

One mistake is that white doesn't play high stones to contest the center. There is K6 but that is the only high stone and it can (and did) become the target of black's attack. It can be a style choice to play low stones but it does make it harder to just play normal moves later, for example if white had just a few more high stones black would not be dominant in the center and it would probably only be one group for white to handle. Not necessarily better moves but for example, I think move 34 could have been the keima to the 4th line and the invasion on the top side could start from J16 because it doesn't have to be that white creates a low group between high black stones.


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 Post subject: Re: Handling groups in the center - KataGo's vs Shodan visio
Post #6 Posted: Sun Nov 07, 2021 5:37 pm 
Oza
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dust wrote:
A very nice lesson which could almost fit with the extended whole-game examples in the Ishida Akira/James Davies book 'Attack and Defence". I hope you consider making this a series.

I think a six group game is hard to play ( as the proverb warns:"Five Groups Might Live But The Sixth Will Die")- so you're setting yourself a hard challenge in this game (or your opponent skilfully encouraged you into it).


It's a series of sorts. See previous posts (I find it hard to link in this archive) and the raw material at https://senseis.xmp.net/?DieterVerhofst ... OfMistakes

Depending on encouragements like these I may find the energy to turn it into something valuable.

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 Post subject: Re: Handling groups in the center - KataGo's vs Shodan visio
Post #7 Posted: Sun Nov 07, 2021 5:46 pm 
Oza
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kvasir wrote:
The reading in such games is very difficult and really needs to be done far in advance.


While better reading is the key to better Go, I do think there are heuristics to be drawn from such analyses. I'm working on a second example where the key understanding is which group(s) of the surrounding position should be pressured so as to keep it a two way struggle. My learning objective here is to play a sharper game and make better positional judgment, not to mimic KataGo's depth of reading. At the surface it looks like KataGo finds random ways to get out of trouble. I'm trying to dig below that surface. Not saying I will be instantly able to. But it seems I have even failed to articulate the potential conceptual learning.

Not a rhetorical question: Is it harder for White to live than for Black to kill? Is there a narrow path to life while Black's options to kill or otherwise profit allow for more error?

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 Post subject: Re: Handling groups in the center - KataGo's vs Shodan visio
Post #8 Posted: Sun Nov 07, 2021 6:25 pm 
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Knotwilg wrote:
Not a rhetorical question: Is it harder for White to live than for Black to kill? Is there a narrow path to life while Black's options to kill or otherwise profit allow for more error?


I guess the answer depends on how you set the baseline for the possible profit. In many situations one is happy to just gain anything when attacking but in others one struggles to gain enough. Often it is even possible to gain while defending.

I feel that the situation in the game you posted is that it is much easier for black. Black has control in the center and is under little pressure. White's only opportunity is to spot, understand and use the two cuts and the 15 move variations that follow. If we put it like this: what if black just plays on autopilot, doesn't white still have to think very hard for 30-50 moves? I'd say that is pretty much the case in that game.

I agree it is interesting how the bots manage to handle such groups, but they also make it look so easy by declaring who is ahead. Just trying to point out that it looks much harder than the KataGo variations maybe indicate.


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 Post subject: Re: Handling groups in the center - KataGo's vs Shodan visio
Post #9 Posted: Mon Nov 08, 2021 2:59 am 
Dies with sente

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Stylistically, I personally find the 22 and 24 (tenuki) combination hard to play. Although in theory it's fine, after the tenuki you have to worry about black reinforcing at the bottom first and getting a large strong territory - and, if you're not careful, your own 'light' stones coming under attack. In this game, I personally wouldn't be happy with from return on investment from this combination (though KataGo is happy with it).

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 Post subject: Re: Handling groups in the center - KataGo's vs Shodan visio
Post #10 Posted: Mon Nov 08, 2021 4:43 am 
Oza
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dust wrote:
Stylistically, I personally find the 22 and 24 (tenuki) combination hard to play. Although in theory it's fine, after the tenuki you have to worry about black reinforcing at the bottom first and getting a large strong territory - and, if you're not careful, your own 'light' stones coming under attack. In this game, I personally wouldn't be happy with from return on investment from this combination (though KataGo is happy with it).


Click Here To Show Diagram Code
[go]$$ Position at move 24
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . O . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . B . . . . . . . . . . . . . . . . |
$$ | . O X . . . . . . . . . . . . . . . . |
$$ | . O X . . . . . . O . . . . . . O . . |
$$ | . O X . . . . . a . . . . . . . . . . |
$$ | . . O X . . . . X O X . . . . O . . . |
$$ | . . O X . . . . . b X . . B . . O . . |
$$ | . . . . . . . . . . . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

White's reduction stone is quite beautifully placed right above Black's sector line. With endgame, the bottom will become ~ 25 points. White has about 15 in both corners, has komi of 6,5 and took sente to play the upper right. Having sente for a 4 point disadvantage is equivalent to being 2 points ahead. Both Black's left stick and White's reduction stone exert some influence but Black is a bit stronger. On the other hand White's bottom right corner can still expand.

White could indeed exchange A for B and then tenuki but I think that's mostly a matter of timing. If Black plays A ...


Click Here To Show Diagram Code
[go]$$ Position at move 24
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . O . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . B . . . . . . . . . . . . . . . . |
$$ | . O X . . . . . . . . . . . . . . . . |
$$ | . O X . . . . . 4 O . . . . . . O . . |
$$ | . O X . . . . . 1 2 . . . . . . . . . |
$$ | . . O X . . . . X O X . . . . O . . . |
$$ | . . O X . . . . . 3 X . . B . . O . . |
$$ | . . . . . . . . . . . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

... White gets to play a powerful turn.

If Black captures a stone ...


Click Here To Show Diagram Code
[go]$$ Position at move 24
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . O . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . O . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . , . . . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . B . . . . . . . . . . . . . . . . |
$$ | . O X . . . . 4 . . . . . . . . . . . |
$$ | . O X . . . . . . O . . . . . . O . . |
$$ | . O X . . . . . 2 1 . . . . . . . . . |
$$ | . . O X . . . . X O X . . . . O . . . |
$$ | . . O X . . . . . 3 X . . B . . O . . |
$$ | . . . . . . . . . . . . . . . X . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


... then White can probably take sente again, or take more influence in the center.

As to "light stones coming under attack", this is by definition not a problem. Light stones are easily disposable in exchange for more outside influence or sente.

In summary, I think the 22-24 combo is quite a classic example of Black responding to a reduction and White playing elsewhere.


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