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 Post subject: Efficiency
Post #1 Posted: Sat Dec 04, 2021 4:03 pm 
Gosei
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Click Here To Show Diagram Code
[go]$$ Position at move 50
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . X . . |
$$ | . . X , . X . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . 2 . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . , . . . . . , X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X . O . . . . . . . . . O . O O . |
$$ | . O X . . . . . . . . . . . . . O X . |
$$ | . O . O . X . . O X . . . . X X O X . |
$$ | . . O , X . X . X O . O . O . O X . . |
$$ | . O X X . 1 O O X O . X . O . O X . . |
$$ | . . . . . . . . X O . . . . O X X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


In Ian Butler's "Murdered by a 2d" KataGo makes a big deal of this position. Black has played the :b1: to capture the 2 stones. White left to attack the right side.

Click Here To Show Diagram Code
[go]$$ Better play by Black
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . X . . |
$$ | . . X , . X . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . , . . . . . , X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X . O . . . . . . . . . O . O O . |
$$ | . O X . . . . . 1 . . . . . . . O X . |
$$ | . O . O . X . 2 O X . . . . X X O X . |
$$ | . . O , X . X 3 X O . O . O . O X . . |
$$ | . O X X . . O O X O . X . O . O X . . |
$$ | . . . . . . . . X O . . . . O X X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


Black should have played this way to take a firm grip on White's stones and make it difficult for him to take profit in the center.

Click Here To Show Diagram Code
[go]$$W White's opportunity
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . X . . |
$$ | . . X , . X . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . , . . . . . , X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X . O . . . . . . . . . O . O O . |
$$ | . O X . . . . 5 3 . . . . . . . O X . |
$$ | . O . O . X . 2 O X . . . . X X O X . |
$$ | . . O , X . X 1 X O . O . O . O X . . |
$$ | . O X X . B O O X O . X . O . O X . . |
$$ | . . . . . . 4 6 X O . . . . O X X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


White can force this way. Black uses 3 stones to capture 3 stones, while White is strong on the outside.

This is a fairly easy sequence to see. However, what is more insightful is that KG prefers this by far to playing elsewhere. The whole sequence is almost forced.


Click Here To Show Diagram Code
[go]$$W Black's alternative
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . X . . |
$$ | . . X , . X . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . 6 . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . , . . . . . , X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X . O . . . . . . . . . O . O O . |
$$ | . O X . . . . 5 3 . . . . . . . O X . |
$$ | . O . O . X 7 2 O X . . . . X X O X . |
$$ | . . O , X 9 X 1 X O . O . O . O X . . |
$$ | . O X X . B O O X O . X . O . O X . . |
$$ | . . . . . . 4 8 X O . . . . O X X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


Black can play away at this point. KataGo evaluates this approximately even but less "natural", taking the previous diagram as the main one to explore.

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 Post subject: Re: Efficiency
Post #2 Posted: Mon Dec 06, 2021 4:14 am 
Lives with ko

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IGS: kvasir
Click Here To Show Diagram Code
[go]$$ Better play by Black
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . X . . |
$$ | . . X , . X . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . , . . . . . , X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X . O . . . . . . . . . O . O O . |
$$ | . O X . . . . . 1 . . . . . . . O X . |
$$ | . O . O . X . 2 O X . . . . X X O X . |
$$ | . . O , X . X 3 X O . O . O . O X . . |
$$ | . O X X . . O O X O . X . O . O X . . |
$$ | . . . . . . . . X O . . . . O X X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


:b1: is also remarkable for the impact it has on the game. Black gets to defend the shape and also starts looking at capturing the white cutting stones as well as moving out the black cutting stones. I'd argue it is not efficiency that matters here but rather effectivity (or should one say effectiveness or impact?).

In my experience efficiency matters a lot more for points and in endgame-ish games than it matters for fights. Effectivity matters the most in fights and can take precedence over efficiency in many situations but the most effective move is often not the best move because in the end it is a game decided by points.

Really good moves are both efficient and effective, like :b1:, but I think it is interesting to make a distinction.

Btw my b40 KataGo slightly prefers to play this way. I think this is because the power of :b1: is is really that it handles the cutting stone and white now needs to mind his own weakness. It is a complete reversal from the game move that gave white opportunity to become strong and begin to capture the cutting stones on a large scale which is also efficient.

Click Here To Show Diagram Code
[go]$$ Better play by Black
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . X . . |
$$ | . . X , . X . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . , . . . . . , X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X . O . . . . . . . . . O . O O . |
$$ | . O X . . . . . 1 . . . . . . . O X . |
$$ | . O . O . X . 3 O X 2 . . . X X O X . |
$$ | . . O , X . X . X O . O . O . O X . . |
$$ | . O X X . . O O X O . X . O . O X . . |
$$ | . . . . . . . . X O . . . . O X X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


I think :b1: really stands out for being effective, it would be a turning point in the game. The efficiency takes secondary role in this position. That is my opinion or observation.

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 Post subject: Re: Efficiency
Post #3 Posted: Mon Dec 06, 2021 4:44 am 
Gosei
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Posts: 1976
Location: Ghent, Belgium
Liked others: 296
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KGS: Artevelde
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Online playing schedule: UTC 18:00 - 22:00
Thanks. To dwell on terminology: with effective you mean "purposeful" (regardless of the way the purpose is achieved) while efficient means "in a good way" (regardless of the purpose)?

That useful distinction is a meaningful comment on the intention of my post. I was indeed suggesting that the reduced efficiency of Black's stones was enough to overcome the possibly higher purpose of a tenuki. You refute that argument by saying it's really the purpose of the moves at the bottom that make them preferable over what happens on the right side.

Still, it matters if you can achieve the same purpose with few moves or more moves. In between Black's atari and the game move is the simple solid connection, which would reduce the temperature to zero.

I find it interesting that this remains a hot place, even if Black has played a move to capture the stones.

(Just reflecting here, need to think more). Appreciate your thoughts and diagrams.

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 Post subject: Re: Efficiency
Post #4 Posted: Mon Dec 06, 2021 5:45 am 
Gosei
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I'd say that move A is more efficient than move B if both moves achieve the same purpose(s), but move A allows to make more points (for instance because it leaves fewer weaknesses, or exposes a weakness of the opponent, or expands further, etc.). Whereas in your example, move A has a double purpose and move B a single purpose.

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 Post subject: Re: Efficiency
Post #5 Posted: Mon Dec 06, 2021 7:12 am 
Lives with ko

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I think what I mean is close to the dictionary definitions in Merriam-Webster:

Effective: "producing a result that is wanted"

Efficient: "capable of producing desired results without wasting materials, time, or energy

In the game position there is a single move that stands out as most efficient and most effective, but I think in many positions it is not clear.

I tried to come up with a situation when black would play differently in the game position, but I realized that this won't work because black is practically capturing cutting stones. I say "practically" because white can escape but is not going to do that. If I change the position it is likely that black will prefer to capture the cutting stone or just not play locally at all.

Capturing the cutting stone changes the balance of power in the center even if white replies locally. White defends locally because the follow-ups are painful. Efficiency is also important, I just wanted to point out that this might be secondary in this case that, I think, is more about the huge impact (or effect) that this play has.

When black connects, just for comparison with the diagram (in previous post) when black captures.
Click Here To Show Diagram Code
[go]$$ -3 pts error
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . X . . |
$$ | . . X , . X . . . , . . . . . , . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . 3 . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . , . . . . . , X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X . O . . . . . . . . . O . O O . |
$$ | . O X . . . . . . . . . . . . . O X . |
$$ | . O . O . X . . O X 2 . . . X X O X . |
$$ | . . O , X . X 1 X O . O . O . O X . . |
$$ | . O X X . . O O X O . X . O . O X . . |
$$ | . . . . . . . . X O . . . . O X X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]

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 Post subject: Re: Efficiency
Post #6 Posted: Mon Dec 06, 2021 8:40 am 
Gosei
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Posts: 1976
Location: Ghent, Belgium
Liked others: 296
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Rank: KGS 2d OGS 1d Fox 4d
KGS: Artevelde
OGS: Knotwilg
Online playing schedule: UTC 18:00 - 22:00
jlt gives a good angle to my skewed analysis: Black's correct move is double purposed; when he captures the wrong way, White can still squeeze out some purpose out of the captured stones

Click Here To Show Diagram Code
[go]$$
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . , . . . . . , X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X . O . . . . . . . . . O . O O . |
$$ | . O X . . . . . B B . . . . . . O X . |
$$ | . O . O . X . W O X W . . . X X O X . |
$$ | . . O , X . X B X O . O . O . O X . . |
$$ | . O X X . . O O X O . X . O . O X . . |
$$ | . . . . . . . . X O . . . . O X X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


Click Here To Show Diagram Code
[go]$$
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . O . . . . . , . . . . . , X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . . X . O . . . . . . . . . O . O O . |
$$ | . O X . . . . W W . . . . . . . O X . |
$$ | . O . O . X . B O X . . . . X X O X . |
$$ | . . O , X . X W X O . O . O . O X . . |
$$ | . O X X . B O O X O . X . O . O X . . |
$$ | . . . . . . B B X O . . . . O X X . . |
$$ | . . . . . . . . . . . . . . . . . . . |
$$ ---------------------------------------[/go]


If you look at the results side by side, the difference in the usefulness of the stones becomes really apparent.

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