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Subject: Re: Tablebases and 50 moves rule

Author: Andrew Dados

Date: 05:55:55 09/15/01

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On September 14, 2001 at 19:09:40, Roy Eassa wrote:

>On September 14, 2001 at 18:26:24, Bruce Moreland wrote:
>
>It's hard for me to understand calling a game a draw when in reality it is a
>win.  The tables do not take sides -- they reflect the actual truth of the
>positions in question.  A fully pre-announced forced checkmate in 51 (w/o pawn
>moves or captures) is now to be a draw??

 Side note:
 It is believed that Thai chess is closest to 'original' chess. And in Thai
chess, when one side has lone King, the other side has some maximum number of
moves given to deliver mate.

That number depends on material balance and eg for KRR vs K is just four(!)
moves.  If 'winning side' can't mate in required number of moves then the game
is pronounced as draw. That rule gives 'losing side' some interesting
possibilities in far endgames.

btw.. there are more Thai players then chess players worldwide....

-Andrew-

>
>
>
>>On September 14, 2001 at 17:40:00, Roy Eassa wrote:
>>
>>>On September 14, 2001 at 12:32:38, Bruce Moreland wrote:
>>>
>>>>The endgame databases don't contain values that are in accord with the FIDE
>>>>rules.
>>>>
>>>>Some have proposed that the FIDE rules be changed, but FIDE seems insistent >that the tables be changed.
>>>>
>>>
>>>Huh??
>>>
>>>
>>>>Some programmers have suggested that the rules be changed for tournaments.
>>>>
>>>>I think that the FIDE rules are fine.
>>>
>>>You're joking, right?
>>
>>There have been a couple of times that people have shown that certain endings
>>must take longer than 50 moves to win.  The first one was KP vs KNN, which was
>>the subject of some remarkable work by Troitsky, well before the advent of
>>computers.
>>
>>As a result of this work, there was a special exception to the 50-move rule for
>>this ending.  This was all a long time ago.
>>
>>When Thompson did his 5-man table work, and someone else (one of the ICCA guys,
>>I think Jaap van den Herik) did work with KRP vs KBP with a pawn ram, it was
>>shown that these endings took longer than 50 moves, and exceptions were written
>>for them.
>>
>>I have a 1986 edition of the FIDE rules, and it mentions that three basic ending
>>classes are extended to 100 moves:
>>
>>1) KRB vs KR.
>>
>>2) KNN vs KP, if the pawn is blocked and not beyond a certain square, which
>>varies with the file of the pawn.
>>
>>3) KRP vs KBP, with an a2/a3 ram.
>>
>>It became obvious that there were more exceptions, for instance KBN vs KN.  That
>>one can take over 50 moves, too.
>>
>>I think that at some point the chess players said enough.  KRB vs KR, for
>>instance, has some pathological cases requiring more than 50 moves, which are
>>not likely to be encountered in actual play.  The other exceptions were getting
>>hard to manage and there were getting to be more endings that would require
>>exceptions.
>>
>>So finally they just canned all of these exceptions.  Now you get 50 moves,
>>period, so the data in KRB vs KR, for instance, is not in accord with FIDE
>>rules.
>>
>>I am in favor of the 50-move rule as it stands now.  I think that if someone
>>wants to use tables, they should put up with this problem or fix it.
>>
>>This issue is a threat to come up at players' meetings at computer tournaments.
>>People who use the tables want the rules changed to accomodate them.  I think
>>that is unfair to those whose programs play in accord with FIDE rules, meaning
>>everyone who doesn't use tables.
>>
>>bruce



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