Computer Chess Club Archives


Search

Terms

Messages

Subject: Re: Improving 6 men index scheme

Author: Vincent Diepeveen

Date: 14:24:50 09/10/02

Go up one level in this thread


On September 10, 2002 at 16:53:36, Heiner Marxen wrote:

>On September 10, 2002 at 15:09:10, Vincent Diepeveen wrote:
>
>>On September 10, 2002 at 14:28:51, Guido wrote:
>[snip]
>>>It is not necessary to have a table for 1891 positions and one for 1128
>>>position.
>>>The 62*61/2 table can be used for all the case N*(N-1)/2 with N <= 62.
>>>All these tables are contained inside the biggest. So 62*61/2 is the
>>>biggest table because kings are already positioned.
>>
>>I do get the idea i could reuse it somehow but i don't understand it
>>completely.
>>
>>suppose i have a chess board sized table [5][5]
>>for a board of 5x5 to place 2
>>pieces. lefttop = 0 of course. and entry 0 is illegal
>>because 2 pieces cannot be on the same square and
>>also second piece is at a higher square than the first:
>>
>
>>Now suppose i use this table to index it for 2 similar pieces
>>after 1 piece has been put already on the board.
>>
>>then i do not see how i index into this table
>>anymore.
>
>Try this one (or a transposition of it):
>table[5][5] = {
>  {-1, 0, 1, 3, 6},
>  {-1,-1, 2, 4, 7},
>  {-1,-1,-1, 5, 8},
>  {-1,-1,-1,-1, 9},
>  {-1,-1,-1,-1,-1} }

I see, that solves the problem completely indeed.

>It also can be computed efficiently on-the-fly with a small table of
>binomial coefficients.

I am very interested in formula's doing that, because
of 5 of the same men i won't put in a table.

Already some mathematical stuff (with correction even!!) from Simon Finn
gave me some great insights here that it should be possible.

>Cheers,
>Heiner



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.