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 Post subject: Re: A vague treatise on influence
Post #121 Posted: Fri Feb 24, 2012 3:24 pm 
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Thanks for the link perceval, reading!

I think the link may have messed with the page-formatting though...

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 Post subject: Re: A vague treatise on influence
Post #122 Posted: Fri Feb 24, 2012 4:17 pm 
Judan

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shapenaji wrote:
I don't see this as an example of non-linearity of influence,


Read the diagram captions! From them, you easily infer that influence is not proportional to the number of influence emitting stones.

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As far as the validity of the light model.


It fails to model connection, life and territory. What is it that it models at all? Proximity * #stones * sign_of_stone_colour. Not completely useless information, it suffices to roughly identify basic moyos and stone distance (regardless of whether the friendly stones are dead or alive...). That is pretty much what you can get from such a model. Too little! My model gives the same information and much more.

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I think the reason why the light model is a good place to start, is that light operates on a shortest path principle.


You forget that shortest distance to dead stones does not assess particularly useful strength of influence.

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The limitation of this approach is that it assumes continuity, rather than computing shortest paths on a grid,


Manhattan distance. Regardless of how light travels, my light-independent model does not have that problem of travel nature of influence and of considering light hurdles.

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But I think that kind of path-ing approach is a good start


It is a bad start because path (of influence particle travelling) is irrelevant. What matters are connection and life status. Simply speaking, go does not work like "Stone A sees (visible seeing along the movement of a light ray, whether straight or zig-zag) stone B and is therefore alive." but works like, e.g., "Stone A can connect to alive group B is therefore also alive.".

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 Post subject: Re: A vague treatise on influence
Post #123 Posted: Fri Feb 24, 2012 4:28 pm 
Judan

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perceval wrote:
your examples Robert, the influence map can be quite easily corrected


Correct it, then consider a particular intersection's influence and tell me what such an influence map says about black / white connection / life / territory.

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by tweaking the diffused influence if the stones are alive or dead


How do you want the tweaking to be defined?

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collaborative diffusion would take care of not diffusing the influence of a stone blocked by some others.


So that such influence spreads also beyond the surrounding of one player's independently alive stones? Failure! You need more tweaking...

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 Post subject: Re: A vague treatise on influence
Post #124 Posted: Sat Feb 25, 2012 2:44 am 
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i am quite mad because i lost a long post because i was not logged. :sad:

Here is what i want ot talk about:
perceval definition of the influence function:
a function B(x,y) on the coordinate of the go board such as:
    B(x,y)=1 if the intersection if an indisputable point for B
    B(x,y)=0 if the intersection if an indisputable point for W
    The sum of B(x,y) on the whole board gives the score difference at the end of the game

This can be losely interpreted as the probability that a given intersection will be B or W at the end of the gamebut this interpretation misses the case of a dead stone with some aji that will help make some point elsewere even if its dead.
you can disagree with that definition if you want but that is what i am going to talk about, it seems an interesting object as being able to compute it for all posistion would solve the game.

As i do not have a god complex i just want to throw some ideas to compute an [u]approximation [/u]of this function.

i agree with you that the influence obtained from a given shape should nto depend on what is on the inside (excpet for life ar death status). For example:
Click Here To Show Diagram Code
[go]$$c 23 black stones
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . O . O . O . O . O . O . O . . . . . |
$$ | . . O . . . . . . . . . . . . . . . . |
$$ | . O . X X X X X . , . . . O . , . . . |
$$ | . . . X X X . X . . . . O . . . . . . |
$$ | . O . X X X X X . O . . . O . . . . . |
$$ | . . . X . X X X . . . . O . . . . . . |
$$ | . O . X X X X X . . . . . O . . . . . |
$$ | . . O . . . . . . . . . . . . . . . . |[/go]

should have the same influence than:
Click Here To Show Diagram Code
[go]$$c 16 black stones
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . O . O . O . O . O . O . O . . . . . |
$$ | . . O . . . . . . . . . . . . . . . . |
$$ | . O . X X X X X . , . . . O . , . . . |
$$ | . . . X . . . X . . . . O . . . . . . |
$$ | . O . X . . . X . O . . . O . . . . . |
$$ | . . . X . . . X . . . . O . . . . . . |
$$ | . O . X X X X X . . . . . O . . . . . |
$$ | . . O . . . . . . . . . . . . . . . . |[/go]


This is what you mean by non linearity of influence (i think)

but more influence than the dead shape:
Click Here To Show Diagram Code
[go]$$c 24 black stones
$$ ---------------------------------------
$$ | . . . . . . . . . . . . . . . . . . . |
$$ | . O . O . O . O . O . O . O . . . . . |
$$ | . . O . . . . . . . . . . . . . . . . |
$$ | . O . X X X X X . , . . . O . , . . . |
$$ | . . . X X X . X . . . . O . . . . . . |
$$ | . O . X X X X X . O . . . O . . . . . |
$$ | . . . X X X X X . . . . O . . . . . . |
$$ | . O . X X X X X . . . . . O . . . . . |
$$ | . . O . . . . . . . . . . . . . . . . |[/go]


My point is thqt the algo in the link above take all this into account:
What you do is to define source for the function, here sources are the intersection where there is a B or W stones.
you define the value of B at those source and the algo compute the function on the whole board by spreading from those sources.

The algo has good properties for the issues above:
it "blocks" influence from inner stone from spilling out of a closed shape.
in addition, the "easy tweak" take live and death status is to seed the algo with value other than B=1 for stones that are not alive, and to go close to zero for dead black stones.

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 Post subject: Re: A vague treatise on influence
Post #125 Posted: Sat Feb 25, 2012 3:15 am 
Judan

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perceval wrote:
a function B(x,y) on the coordinate of the go board such as:
    B(x,y)=1 if the intersection if an indisputable point for B
    B(x,y)=0 if the intersection if an indisputable point for W


Whatever you define "indisputable" to be, such is too simplifying because it does not distinguish the intersection's degrees and in particular does not distinguish Black's connection status from White's connection status from Black's life status from White's life status from Black's territory potential from White's territory potential. By ignoring degrees and putting the three aspects in the same bowl, you only get a too rough approximation of the kind yes or no for "Black has non-negative and White has negative connection status there AND Black has non-negative and White has negative life status there AND Black has but White has not territory there". IOW, all that you get is a special case of my model.

Quote:
The sum of B(x,y) on the whole board gives the score difference at the end of the game[/list]


Wrong. Influence changes dynamically (at least) until the game end! You only get the score difference at the game end if the game end is already reached. For that, simpler models than yours suffice.

Quote:
This can be losely interpreted as the probability that a given intersection will be B or W at the end of the game


Who cares? Influence is relevant DURING the game and not for predicting which intersections score for whom at the game end. If you want that, then a territory definition similar to n-connected is useful: how often a player can pass while an intersection is still his territory.

Quote:
but this interpretation misses the case of a dead stone with some aji that will help make some point elsewere even if its dead.


Use my model and you get such information implicitly.

Quote:
you can disagree with that definition


The point is not that one would need to disagree with the definition but that it provides by far too little information!

Quote:
if you want but that is what i am going to talk about, it seems an interesting object as being able to compute it for all posistion would solve the game.


No. Too little information.

Quote:
As i do not have a god complex i just want to throw some ideas to compute an [u]approximation [/u]of this function.


You are too pessimistic. As a special case of my model along the thoughts outlined above, calculation is reasonably possible for human beings. Only PCs can have greater problems because they are in greater need of reducing computational complexity related to proof-play game tree exploration.

Quote:
should have the same influence than:


No. Not the same. One has a *-alive group. The other has a 2-alive group. For practical purposes, this is almost the same. Almost but not exactly.

Quote:
The algo has good properties for the issues above:
it "blocks" influence from inner stone from spilling out of a closed shape.


This is insufficient since some influence can spread from inside to outside.

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