Computer Chess Club Archives


Search

Terms

Messages

Subject: Re: Tablebase Questions

Author: Dieter Buerssner

Date: 16:38:52 03/19/02

Go up one level in this thread


On March 19, 2002 at 13:40:54, bob o wrote:

I give a slightly different answer:

>4. Is it possible for a program to need just one of the tablebase files instead
>of the pair? For instance, let's say that you had an endgame of: white- ke1 pawn
>e2, black- ke8. And suppose you only had kpk.nbw.emd. Is it possible for the
>program with white to say, "Ok I know that I have a mate in N moves." Then it
>makes a move. Then black says "I can't find the correct TB file. But I found
>kpk.nbw.emd. Now let me search every possible black move for me and white's best
>reply, and leave him in the worst possible position." It seems that if this is
>possible, then you could cut the storage space in half by doing a quick 2-ply
>search.

Yes this, or similar methods (just do a normal search, probe after each
capture/promotion, and also one half move later - the one half move later is not
needed when allways both TBs are present) are possible. I tried it (because on
my Fritz 6 CD I only had one of the KPPKP). The (not so surprising) result: it
makes the nodes/s faster (because Cache can be used more effeciently). It can
make (with the method I used) find the engine find some moves at one depth
later. All in all, it was not really clear to me, if it is a win or a loss on my
computer. Most modern computers have more memory than mine, and perhaps it is
allways a loss there, to miss one of the pair.

Most engines are probably not prepared to handle the case, that only one of the
nbw/nbb pair is present.

>5. I'm not quite clear on what info is in which TB file. For instance, let's say
>we have a series of kqkr endings. In which files are the following (kqkr.nbb or
>kqkr.nbw)

I am not totally sure, but I think:

>  1. white's queen vs. black's rook, white to move

kqkr.nbw

>  2. white's queen vs. black's rook, black to move

kqkr.nbb

>  3. white's rook vs. black's queen, white to move

kqkr.nbb

>  4. white's rook vs. black's queen, black to move

kqkr.nbw

Regards,
Dieter




This page took 0 seconds to execute

Last modified: Thu, 15 Apr 21 08:11:13 -0700

Current Computer Chess Club Forums at Talkchess. This site by Sean Mintz.