# Computer Chess Club Archives

## Messages

### Subject: Re: likelihood instead of pawnunits? + chess knowledge

Author: Ingo Lindam

Date: 11:33:13 10/26/02

Go up one level in this thread

```On October 26, 2002 at 10:28:07, Bob Durrett wrote:

>This is to check to see if I understand your idea:
>
>One could go to a very large collection of high-quality master games [Megabase]
>and do some research on patterns.  For each pattern, one could first identify
>all games in which that pattern occurred.  Then, in each game, one could
>estimate your three probabilities at the point in the game where that pattern
>first occurred.

I would rather say to estimate the probabilities over all the games the pattern
"occurs" (you define that in several ways, denpending on whether you are
interested just in static patterns or also in patters just occuring in a single
position or just in pattern occuring after move 15 or just occuring in
midgame,...)

>Repeat for all patterns of interest, to produce a table of
>data.  The first column of the table might be a name of the pattern and the
>statistical information such as confidence levels.  Each row would be for a
>different pattern.

The pattern might have just a representation without a name at first stage.

>Am I on track so far?

You are on the track. Ofcourse it might be possible to have a very limited
class/set of pattern first that occur very often and then enlarge the set of
pattern by generating more special/complex pattern that occur less often
offering more significant probabilities.

>One could extend this idea to identify degree of correlation between a new
>pattern [which unexpectedly occurs in a game being examined or played] and one
>of the patterns in your selected set of patterns.  There would have to be
>criteria and a method for computing the correlation numbers.  [This could get
>messy.]

Yes, that could get messy... and I dont like the idea of evaluating pattern (too
much) that I don't have seen in my data base. The main idea of using pattern is
to use the experience of million of games to evauate positions that I have never
seen, but that are "similar" (at least in some pattern) to a sufficient number
of games.

>The next logical step would be to compute the probabilities for the new
>position.  This set of probabilities [a probability vector?] might be regarded
>as being a function of the similar positions.  Generally, one would expect that
>there would be several or many positions in your position database which would
>be regarded as being similar enough to be considered.

Yes there should be a lot of patterns in most positions I have to evaluate that
I can evaluate by the experience of data base.

>Am I still on track?

You are!

>Incidentally, the programmers have the trivial [? : )] task of figuring out how
>to make all this work.

Certainly not trivial. And certainly some work to do for the computer, but
atleast I may be sure there are pattern saying something about the position (we
use a lot of them in every game... perhaps not in every game)

>Back to the idea:
>
>All of this must be done for each move.

Not generating the pattern and estimating their probabilities, but estimating
the probabilities of the positions I want to evaluate, yes!

>Would you still have search algorithms?

Yes, ofcourse!

>If so, then all this maybe would have
>to be done at each move in a string of moves being evaluated by the searching.
>This all appears very interesting for the future computers where there might be
>millions or billions of microscopic microprocessors on a single chip.  One >could have each of these microprocessors dedicated to a single pattern in your
>database of patterns.

Well, ofcourse I have to do a lot of evaluation for the positions I want to
evaluate this way... but ofcourse the is also a lot of work that is of use more
than one time in the search tree... and I dont think of using complex patterns
for all positions of current search trees. It is possible to use them just for
within a certain scope in order to get a very valuable pruning of the tree. But
ofcourse if you are right with your optimistic look into the future of computer
development I could do much more.

>Well, my wife is hollering for me to come eat breakfast, so that's it for now.

Ok, lets return to real life... for me it will be dinner soon. I will bake  some
pancakes for my wife before she comes home from work. I guess they will be much
more appreciated than my weird ideas. ;-)

Ingo

```