Computer Chess Club Archives


Search

Terms

Messages

Subject: Re: EGTB: Better algorithm

Author: Tony Werten

Date: 06:57:35 04/08/01

Go up one level in this thread


On April 08, 2001 at 08:41:19, Uri Blass wrote:

>On April 08, 2001 at 06:47:56, Aaron Tay wrote:
>
>>On April 08, 2001 at 06:14:44, José Carlos wrote:
>>
>>>On April 07, 2001 at 11:18:34, Urban Koistinen wrote:
>>>
>>>>I have written down a algorithm for computing endgame tablebases that should be
>>>>about 10 times quicker than the Nalimov algorithm and requires much less ram.
>>>>It is similar to the Arlazarov&Futer algorithm of 1979 but is more general as it
>>>>does not require a pawn.
>>>>It might be too technical for most here,
>>>
>>>  Thank you. Too technical algorithms are not for a crowded-of-programmers forum like this. We wouldn't understand anything.
>>>
>>>  José C.
>>
>>Hey , be nice. He's new here.
>>
>>He is just feeling a little fustrated after posting at r.g.c.c and getting only
>>one response. Knowing the high level of general technicial expertise here, I
>>suggested to him  that he should post here.
>>
>>So what do the experts think? Is the algorithim as good as he claims? Layman
>>like me want to know!
>
>1)I tried to explain the paper in more words in order to understand it and the
>first part that I did not understand was the sentence:
>"t4 depends on t3 and d"
>It seems to me that t4 is dependent also on t1.
>
>Here is an example of position in t4

Why is this an example of t4 ? Might be t100, white has just captured a queen.
Or t99, black has taken the other white queen.

Counting the number of moves for the 50 move rule has nothing to do with
distance to mate. ( Or I really don't get it )

BTW with pawns on the board, t100 and t99 will almost be the only tables with
any information.

cheers,

Tony

>
>[D]2k5/8/2K1Q3/8/8/8/8/8 b - - 0 1
>
>The position after Kb8 is in t3 but the position after Kd8 is in t1.
>
>I prefer not to try to understand the rest of the paper before I understand this
>point.
>
>
>
>2)Here is my explanation of the part that I did understand:
>
>
>I call capturing or pawn move in the same word conversion.
>
>tables ti are clear
>They include all the positions when it is a win for white but white need i plies
>to get the conversion.
>
>Table d include only legal positions that are not stalemate and black cannot
>save itself by conversion.
>
>We want to find positions that are win for white.
>other positions are not intereting because it is obvious that they are not win
>for white.
>
>It is clear that t1 depends on t0 and previous tables that can be reached by a
>conversion(a position is in t1 only if white wins by conversion or by checkmate
>in 1 ply).
>
>t2 are positions when black is to move.
>The position is legal and black cannot save itself by conversion and it means
>that t2 is included in d.
>If black try to play a move that is not conversion it gets to position in t1 so
>it depends also on t1.
>
>t3 are positions when white is to move.
>White cannot win by conversion otherwise the position is in t1.
>White can get by a move that is not conversion to position in t2.
>
>This is the reason that t3 is dependent on t2 and t1.
>
>Uri



This page took 0.01 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.