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Subject: Re: EGTB question

Author: Mike Hood

Date: 05:27:37 09/28/01

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On September 19, 2001 at 04:23:39, Les Fernandez wrote:

>Has anyone tabulated the total win-lose-draw-broken positions for first the 3
>then 4 and then the 5 piece sets?  I know that the information is available on
>Bobs ftp site but hoping that someone has already done it for both WTM and BTM
>so I dont have to do them one by one.
>
>ie:
>
>EGTB     WINS     LOSE     DRAW     BROKEN
>
> 3
> 4
> 5

This is theoretically possible, but not very sensible at the moment. Most of the
TBS files on Robert Hyatt's ftp server are defective, probably due to a bug in
TBSTAT.

For instance:

krrk.tbs -- On black's move there are 1032 positions that lose in 16, but on
white's move the longest mate is Mate in 7.

kqrkr.tbs -- On black's move there are 60 moves that are Mate in 5, but there
are ZERO moves that are Mate in 4.

kbpk.tbs -- On white's move there is 1 position that is Mate in 31, but there
are ZERO moves that are Mate in 30.

In most of the TBS files the number of broken positions is not listed.

Over 50% of the TBS files are obviously defective, and I can't vouch for the
validity of the others. And, to ask a naive question, shouldn't the number of
Mates/Losses/Draws in a pawnless tablebase always be divisible by 4?

I've reported the bug to Eugene by email a few weeks ago, but it hasn't been
fixed yet.

Mike

**** Dansez de la apusul pana la rasaritul soarelui ****




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