Hi everyone!

Since your answers to my last question have been most helpfull, I have another one for you:

In many books about go the technical terms "influence" and "over-concentrated" are used. I guess that I have a rough idea by now how an influential and how an over-concentrated group look like and what the consequences might be.

But, since both terms are used strictly speaking in a metaphorical way (nothing floats in an influential group and no chemicals are mixed in an over-concentrated one) I don't get the game mechanics behind all that. What I mean is:

Can anyone explain how the influential group works it's "magic" influence? And how exactly do over-concentrated stones obstruct each other?

Thanks again!

Influence is influential because it turns out that having those particular stones in that particular sort of shape affects the plans players may statistically successfully accomplish nearby, thereby encouraging particular other shapes and plans and affecting the likely direction of the game tree.

That is...it's really hard to explain in a useful way other than 'play games and see what happens'. People can comment on particular positions, but ultimately stuff like this isn't some precise reason but a set of general phenomena that you need to play to recognise and understand.

Do you have an example position, perhaps from one of your games, in which we could comment on the role of influence?



This one is easier to mathematically define. It isn't about obstruction (that would be, if anything, a question of shape), but instead efficiency. For instance, you could spend your first three moves surrounding a single point of territory in the very corner of the board, but their value would be 1/3 points each (plus some influence, but lets not get into that ). They are overconcentrated because this isn't enough points-per-stone to win the game; if you instead played a single stone on the 3-3 point it would almost certainly claim that single corner point by the end of the game - plus a few more - thereby being worth more like 5 points for the single stone plus much more influence than the 3 little corner ones.

That's what overconcentration means, though it's usually harder to clearly see than in this contrived example. In general, it refers to spending too many stones for too few points. Sometimes it's a natural result of a sequence, it's okay to be in a position that would normally be overconcentrated if you force your opponent to also take some disadvantage.

A more natural example would be if you build a really big wall, but then make a really small extension from it. This is normally overconcentrated because all those wall stones could safely support a really big extension, as the opponent can't easily invade since the wall would let you attack him strongly.

Again, if you have some actual game examples, it is easier to point out on a relevant way.

Before he starts posting a long dialogue on what you are asking for, I'll tell you that Robert Jasiek will be delighted to let you know which of his books will address the precise definitions of what you are looking for.

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Go is such a beautiful game.

Wow, you guys are fast! (Or bored with the other things you have to do )

Thanks!

I don't think "influence" is much of a metaphor - the presence of a large thick black group on the left-hand side of the board should indeed influence how white plays on the right-hand side. (A very simple example of this phenomenon: it may break a ladder. Another simple example: if white plays in such a way that allows black to deprive him of eyespace on the side and force him out to the centre, it's harder for white to run to safety. There are many indirect ways of influencing and being influenced.)

One of the most unique concepts in go is the following:
- The board is so big that it's possible to have several local "fights".
- Each move in one of those local "fights" have different consequences depending on the situation far away.

"Influence" is the name for "Situations that occur far from this place will be influenced favorably by this influence color.".

So, Influence is the effect* this position has on other distant positions. That's why you can be happy changing territory for influence if later that influence helps you make a more favorable exchange somewhere else that gets you more territory.


*:and never forget that among the "effects" influence can have on distant stones, a common one is "death". See, ladders.

Over concentration expresses the fact that one shouldn't judge a position only by its result, but also by its cost.

i.e.: If you get 10 points of territory with four stones it can be fine. If you surround those same ten points of territory with twenty stones, you're over concentrated.

Using the "Over-concentration" is a way of saying "It may be fine locally, but at such cost that I know it's bad somewhere else without even needing to go check."

Forcing someone to be over concentrated is like making him pay several times more money for the first item in an auction. Yes, he did get that item, but now he won't have money to bet in any other item.

In go, influence and territory have an expected cost in stones depending on the moment in the game. If you pay much more than that, you're overconcentrated. Enclosing a 3x3 corner with your first two stones may be fine, enclosing it with four isn't.

OK, I think I got a better idea now. The over-concentrated thing I obviously mistaked for "bad shape", but now I think I got it.

The influence part seems the harder one but I just found another tread with some examples.

So, thanks everyone for now.

Neither influence nor overconcentrated are metaphors. The basic idea of overconcentration is plain enough, but in practice it is an advanced concept, because recognizing overconcentration requires judgment. Influence is a Western concept, introduced by Zobrist in his computer program some 45 years ago. Again, the basic idea is plain enough. Stones exert influence on empty points and other stones. The problem is that there is no consensus on how to measure influence. Furthermore, modern Monte Carlo go programs make no use of it. The concept of influence may therefore be vague, but it is not metaphorical.

Click Here To Show Diagram Code

[go]$$ How many points?
$$ ----------------
$$ | . X . . O . O .
$$ | X X X X O O O .
$$ | . X . . O . O .
$$ | X X X X O O O .
$$ | . . . . . . . .[/go]

Not counting the surrounding region, how many points of territory does each player have in this corner? White obviously has 2 points, but what about Black?

Click Here To Show Diagram Code

[go]$$W White plays first
$$ ----------------
$$ | . X . 1 O . O .
$$ | X X X X O O O .
$$ | . X . 2 O . O .
$$ | X X X X O O O .
$$ | . . . . . . . .[/go]

If White plays , guarantees 3 pts. for Black. Similarly, if White plays at 2, Black at 1 guarantees 3 pts. (We say that 1 and 2 are miai.)

Click Here To Show Diagram Code

[go]$$B Black first
$$ ----------------
$$ | . X . 1 O . O .
$$ | X X X X O O O .
$$ | . X . 2 O . O .
$$ | X X X X O O O .
$$ | . . . . . . . .[/go]

If Black plays , guarantees that Black gets no more than 3 pts. Similarly, if Black plays at 2, White at 1 holds Black to 3 pts.

Click Here To Show Diagram Code

[go]$$ 3 points for Black
$$ ----------------
$$ | . X C . O . O .
$$ | X X X X O O O .
$$ | . X C . O . O .
$$ | X X X X O O O .
$$ | . . . . . . . .[/go]

We evaluate each of the points as 1/2 pt. for Black, for a total of 3 points.

Click Here To Show Diagram Code

[go]$$ Influence
$$ ----------------
$$ | . B a b W . O .
$$ | X X B B O O O .
$$ | . X . . O . O .
$$ | X X X X O O O .
$$ | . . . . . . . .[/go]

That means that the net influence of the and stones on "a" should be 1/2 pt. for Black, and the net influence on "b" should be 0. According to the theory that I am developing, the stones exert a total of 1 pt. if influence on each of "a" and "b", while the stone exerts 1 pt. of influence on "b" and 1/2 pt. of influence on "a". The net influence on each point is thus correct.

The measurement of influence is far from obvious, which is why there is no consensus.

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Influence: Stones are on the board such that they are useful for limiting the possible good outcomes for the opponent, and maximizing the possible good outcomes for yourself. Playing stones in a way that generates influence, therefore, is often an investment for the future. You can focus on getting immediate territory by surrounding points early in the game. But this doesn't necessarily help much in the future. Typically, influence is manifested in the form of stones that are in or around the center of the board.

Over-concentrated Stones: In the game of go, whenever you play a move, your opponent gets to play one, too. Therefore, efficiency becomes important. If you play 15 stones all in the same localized area, it's possible that none of the stones are really hurting that local area, but in investing all of these moves in a single location, you are negating your opportunity to play in other areas of the board. The more you negate the opportunity to play in other areas of the board by playing moves that have little use, the more opportunity your opponent has to gain an advantage. Over-concentrated stones are stones that are not maximizing their efficiency, often manifested as stones that are "too close together".

Bad Shape: Enumerating all possible board positions aside, certain formations of stones are efficient, flexible, and useful for making points and/or attacking the opponent and/or defending yourself. Such shapes are "good" in the sense that they commonly lead to good future outcomes. "Bad" shapes, on the other hand, are inefficient, and not as useful for making points, living, attacking, and the like. Despite the good/bad terminology, the idea of "good" and "bad" shape is a heuristic, and sometimes playing "bad shape" is the best move. Typically, however, before playing a move that works with bad shape, it might be good to try to see if there is a way to do so in good shape, so as to lead to greater efficiency and greater probability of having a good future result.

All of these terms are related to a common notion: efficiency. The game of go is about efficiency.

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My definition

"
A player's live (outside) stones have a greater impact on other intersections the more

easily friendly stones there can be connected and get life,
easily the player can make territory there,
difficult it is for opposing stones there to be connected and get life,
difficult it is for the opponent to make territory there.
"

might be sufficiently exact for your taste:) IOW, influence measures, for each intersection, the impact on either player's degrees of connection, life and territory.

I would say its like this...

Territory (think of it as cash):
-Sure points for now
-Cannot be reduced (for the most part)


Influence (think of it as power):
-Is not worth anything right now
-Can be used for helping your weak groups to escape or break ladders
-Allows you to invade the opponent's weak areas easily since you can always run out to the center if you have influence
-Allows you to extend much farther than normal because you have influence to help attack the opponent if they try to invade/cut
-Allows you to be more aggressive throughout the board because of the other mentioned things
-Sometimes, in certain cases, you may use influence to create a large "moyo" and either take more cash than the opponent will and win by points, or attack their invasion stones and make profit elsewhere

Basically.....

Points= Cash
Influence= Power

Remember..

Cash= Can help you win by having more points
Power= Can help you gain control of the game and take charge

Thank you for so many different yet interrelated views. Most helpfull!

And of course now I have the metaphor-thing right too: Life is a metaphor for go.