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Subject: Re: Ten years later: revising EPD/FEN/PGN

Author: Heiner Marxen

Date: 06:52:45 09/10/03

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On September 09, 2003 at 23:11:08, Steven Edwards wrote:

>On September 09, 2003 at 22:22:32, Dann Corbit wrote:
>>On September 09, 2003 at 18:33:22, Steven Edwards wrote:
>
>>>5. The centipawn evaluation  operand type probably needs to be deprecated and
>>>replaced with a pawn evaluation operand type with a provision for sub-pawn
>>>decimal resolution.
>
>>perhaps ced instead of ce.
>
>Yet not everyone uses centipawn units.  The SPCT (Steven's Portable Chess
>Toolkit) uses micropawns for all internal operations except for a centipawn
>mapping for transposition table entry storage.  At the moment I'm thinking of
>using "pes" (pawn evaluation score) and reporting it as a real (i.e., with radix
>point) value.

What about a binary (hex) notation for reals?
Some programs use a fix point implementation, e.g. pawn=128 or 256.
Another option may be a rational number like: 320/100 or 410/128.

Anyhow, a real number is a good idea.

>Side note:
>
>The SPCT has classes for both scores and for the alpha beta scoring window.
>Here's a snippet from the CTScore class header file:
>
>// Special score values
>
>#define CTSValNInf ((CTScoreValue) 0x80000001) // Negative infinity
>#define CTSValPInf ((CTScoreValue) 0x7fffffff) // Positive infinity
>
>#define CTSValBust ((CTScoreValue) 0x80000000) // Broken
>#define CTSValEven ((CTScoreValue) 0x00000000) // Balanced
>
>#define CTSValLose (CTSValNInf + CTMatePlyLen) // Active color is checkmated
>(lose in zero moves)

A code for this is missing in the current ce-coding for mate values
(it is used for "illegal").
The new coding should provide a code for "this is mate".

Heiner



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