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Atsui

 

Old Atsui
   

Here you can find the discussion on influence, thickness and atsumi. It has been WikiMasterEdit-ed into thickness. It should be noted that we previously thought that atsui meant 'thickness', whereas it means 'thick' and atsumi means 'thickness'.

DieterVerhofstadt

In Go, several balances are to be maintained throughout the game. One of those is the balance of territory against influence. Influence is also referred to as thickness. Both terms, which have a slightly different feeling, can be a translation of the Japanese atsumi .

Understanding thickness is key to the game of Go, and the author of these lines certainly does not want to state that he does so. Here, an attempt is made to describe thickness.

We say that a group is thick if it has no defects. The stones belonging to the group are connected in a major way, and have sufficient potential for eye-space. Since one doesn't have to worry about this group, all actions that take place in the immediate neighbourhood favour the owner of the group. The group is said to have influence on that area. Here is an example:

[Diagram]
Diag.: Thickness arising from a [Sansan]invasion

Black has the hoshi stone and the marked stone in place. White approaches with the keima kakari at 1. Black answers with the pincer at 2. White jumps into the corner with 3, and up to 8 the sequence is very common. White has thus taken territory but Black has created a group, consisting of a wall 4-6-hoshi, virtually connected to 2 and 8. The marked stone provides for sufficient space to make eyes for the group. The black configuration is regarded as thick and influences the center and the right side.



If the marked stone in the previous diagram is not in place, Black might block the san-san invasion from the other side, in order to create thickness.

[Diagram]
Diag.: Thickness arising from a [Sansan]invasion

Again, Black builds a wall. The marked stone is now closer to the wall, but because a white stone is already in the area, this makes perfect sense. This configuration is again regarded as strong, and influences the center and the lower side.

--DieterVerhofstadt



See also: PlayAwayFromThickness


HolIgor: Comment. I think that it is reasonable to distinguish between influence and thickness. Influence is the effect the stone has on the game flow. It is long range effect, because a ladder stopper changes balance in in the opposite corner. Thickness is absence of weak points. Quite often kikashi is played to create influence. These stones are treated lightly, are usually quite thin, but make their influence on the game.


DieterVerhofstadt: True. Maybe we should make a separate section for influence, where we say each stone has a certain influence on the game, and that major influence comes from thick groups.


MortenPahle: (Tongue-in-cheek-comment going slightly off-topic) So, you could say that kikashi played against thin positions to create influence end up making the opponent thicker and themselves stay thin :-)

Getting back to topic, I agree that there is a significant difference; thickness to me is more local than influence. I also think that influence is more dynamic: you can erase the opponents influence, but a thick position will stay thick. I think I've seen thickness described as 'without local defects' somewhere.

Does the Japanese 'atsumi' mean both these concepts at once or do they have other concepts that are used for respectively thickness and influence as well?


HolIgor: In reply to Morten's (tongue-in-cheek-comment). I am afraid that this technique is well above my level. As usual there is an obscure proverb that gives an advise to treat kikashi stones lightly. There are some examples from professional games. But when I look at the examples my heart sinks. I would never play like this.


AlainWettach: I would define thickness as the local property of a group of stones to stand on its own. The ultimate thickness being the group living regardless of what the opponent plays in the neighbourhood. In that sense, a group which is alive if you answer kikashis by the opponent is not as thick as a group which _hasn't (Thanks Dieter ;-)) to answer kikashis.

Influence or power is a more relative concept because it measures the effect of thickness in a specific position. Influence depends on the degree of thickness of the group, but also on the neighbouring positions. The influence of a group with two eyes (the ultimate thick group!), for instance can be zero if the group is completely surrounded.

Kikashi and influence

As to Morten's considerations on kikashis, I think that there is a close relation between thick/thinness and kikashis. This brings us to the complex question of good and bad forcing moves (usually only the good forcing moves are called kikashis). A real kikashi shouldn't make the opponent's thin group thicker. Kikashis are usually played against strong groups. Just an example:

[Diagram]
Diag.: A good kikashi

This is a common takamoku (5-4 point) joseki and the marked stone is a good kikashi. Black should answer it at the marked point.

It doesn't make the black group thicker, since white couldn't cut anyway and it has some influence for white (it might break a ladder for instance) even if the marked stone cannot be considered as "thick". So this shows that even "weak stones" or, in this case "light stones", have influence. Here white wins 1 in terms of influence and loses 0 in terms of potential.



[Diagram]
Diag.: A bad forcing move

In this position, black 1 would be a bad forcing move (a thank-you move). Of course, the stone is not completely wasted since it exerts some influence (it could be a ladder breaker for instance), but black could and should have cut. This means that the peep makes white thicker since he won't have to worry about beeing cut whatever black plays in the area. One could say that black 1 wins 1 in influence and loses a lot in terms of potential.



I have just updated the Kikashi entry, duplicating with Alain's examples above. And I still think that atsumi, which we translate as thickness, is a measure of influence AND strength (invulnerability). A surrounded living group has no influence, well, then I couldn't call it thick. Otherwise, the proverb PlayAwayFromThickness makes no sense. But that amounts to a discussion about the gender of angels, I suppose. Once this discussion has settled down, some work has to be done in order to present the atsumi/influence/thickness and Kikashi entries in a nice and consistent way, no ?

-- DieterVerhofstadt


Alain: A group which is alive if you answer kikashis by the opponent is not as thick as a group which does not have to answer kikashis, and A real kikashi shouldn't make the opponent's thin group thicker.

I agree with both these statements, but there is an inconsistency between them, no? If the group which has a kikashi played against is thick enough to ignore the kikashi, we agree that the kikashi was just a wasted move. But, if the group is so thin that it needs to answer the kikashi, the group will, per definition, become thicker afterwards. So I think that a kikashi will always make the 'kikashi'ed group thicker. Of course, a good kikashi should gain more than it loses, but I think that this assessment is very difficult to make sometimes (and very rarely 'black and white'). See also my comments on the Kikashi page.

Anyway, like Dieter said, someone will need to WikiMasterEdit these pages when the discussion dies down - good luck :-)

-- MortenPahle

Morten, you are right, it might seem contradictory. In a way, even good kikashis make the opponent "thicker". What I wanted to point out is that forcing moves which kill potential on "really thin" groups (those you might want to attack later) should not be played. Another concept which should also be taken into consideration is light/heaviness.

It is often a good idea to refrain from playing forcing moves if you think that, by doing so, you lose potential you might use later in the game. A good example for this is the peep on an ikken tobi.

[Diagram]
Diag.: 2 forcing moves possible

In this example, black might peep at a or b, but it is impossible at this stage to say which one is better. So, it is better not to play either a or b and to wait the right moment.



[Diagram]
Diag.: Thicker, but also heavier

White 2 is a classical example of a forcing move on a more or less "thin" group in order to make it heavier (but also thicker).

In some cases, the border between thick and heavy is very difficult to see, even by the pros!

AlainWettach



This is a copy of the living page "Old Atsui" at Sensei's Library.
(C) the Authors, published under the OpenContent License V1.0.