Distributed Chess Theory Was: Re: [rc5] v3

Skip Huffman SHuffman at Atl.Carreker.Com
Tue Oct 28 14:14:52 EST 1997

On Tue, 28 Oct 1997 11:38:13 -0700, Sebastian Kuzminsky wrote:

>   Slight optimization:  you never need more than 5 bits to encode the
>destination, and usually less.  The piece with the highest number of
>possible moves is the unobstructed queen.  This piece has max 28
>possible places to go.  The rooks and bishops never have more than 14
>places to go.  The knights and kings have no more than 8 places to go,
>and the pawns have one or two.

That does save one bit, but it significantly complicates the design of
the client.  The client now has to keep a separate table for each type
of piece so as to translate its "move code" into a board destination. 
The trade off may or may not be worth it.  Also it would make pawn
conversions more complicated because a pawn that has reached the eighth
rank may have become any of several pieces with different movement

Lets say a pawn has moved to the eighth rank last round.  Lets call
this pawn Piece 1.  It is currently in square 64.

A command comes in to move that pawn: 1  1  (Apply a Type One move to
Piece One)

If the command is relative, a Type One move could be "move one square
left" if the ex-pawn is now a queen, or "move one square diagonally
down left" if the ex-pawn is now a bishop, or "move two squares left
and one down" if the ex-pawn is now a knight.

If the command structure is absolute, then a Type One move always means
move the piece to Square One.  No ambiguity.  ( We are still unsure
what the ex-pawn has become, either a bishop or a queen, but it really
does not matter.)

Skip Huffman
Atlanta Office
Quality Group
"A penny saved may be a penny earned, but it's a waste of
 a deposit slip and it really pisses off the tellers."

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