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Subject: Re: Parallel algorithms in chess programming

Author: Josť Carlos

Date: 13:14:02 04/17/01

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On April 17, 2001 at 15:16:46, Tony Werten wrote:

>On April 17, 2001 at 09:21:42, Josť Carlos wrote:
>>On April 17, 2001 at 03:08:42, Tony Werten wrote:
>>>On April 16, 2001 at 18:15:52, Dieter Buerssner wrote:
>>>>In a different discussion, Vincent wrote the following:
>>>>>It is not difficult to implement the form of parallellism as used by
>>>>>Rudolf. Invented by a frenchman who couldn't spell a word english and
>>>>>who wrote an impossible article for JICCA (did anyone proofread it at
>>>>>the time as i'm pretty sure they didn't get his parallel idea?).
>>>>>At the time when i read the article i was pathetically laughing about it
>>>>>actually as i also didn't get the idea of the frenchman. But it appears
>>>>>everyone who can make a chessprogram work under win2000 can also get
>>>>>within an afternoon his program parallel to work. Then some debugging
>>>>>and a day later it works cool.
>>>>I'd be very interested in this algorithm, that can be implemented at an
>>>>afternoon :-)
>>>>Could you point elaborate on this.
>>>>BTW. In Paderborn, Roland Pfister also told me, that he knows this from Rudolf
>>>>Huber, and he even started to explain it to me. Somhow, we (or me) got
>>>>distracted, and I cannot remember the essential things.
>>>>What I remember is, that the time consuming work, of making your
>>>>search/evaluation routines free from all those global variables is not needed.
>>>I haven't tried parallelism yet, but my (very) simple approach would be:
>>>Since my program spends most of its time in eval(), split it in evalblack() and
>>>evalwhite(). No need for many changes. Haven't got a clue what the speedup would
>>>be, but it's easy to try.
>>  Are you sure you spend most of your time in eval? My problem is inCheck()
>>since ever. That's where my prog spends most of the time.
>Then you're doing something wrong.
>Take the last move. To make it easy: If it's a special move do your normal check
>If it's not look if the fromsquare is a queenmove from the king. If not it
>cannot be a discovered check else walk from to king in the direction of that
>square and look if there a checking piece. Stop if blocked.
>Do the same for the to square.

  I'm trying something like that in my new rewrite, but it's much more
complicated. Consider en passant captures (which removes an enemy pawn), a
promotion (which makes a new pice to appear on the board), castling, captures...
  You must check for _many_ special cases.
  That's my approach now, but I'm really far from finishing it, because the more
I implement, the further I realize I'm from catching all cases.
  Anyway, I can very well be wrong, and actually be very close to the end... I
hope so :)

  Josť C.

>If this takes more than 5% then it's time to make your evaluationfunction
>>  The good thing is that, everytime I want to improve the speed of my program, I
>>know exactly where to focus on :)
>>  I suggest you to profile your program to know exactly where the time is spend,
>>although probably you've already done this.
>>  Josť C.

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