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Subject: Re: Move ordering ideas

Author: Ulrich Tuerke

Date: 08:17:18 03/08/01

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On March 08, 2001 at 10:37:36, Miguel A. Ballicora wrote:

>On March 08, 2001 at 06:51:13, Ulrich Tuerke wrote:
>
>>On March 08, 2001 at 06:26:05, Ed Schröder wrote:
>
>>>
>>>The second idea to sort "the remaining moves" by a piece_square table
>>>has been in Rebel from the very early start. Last time (about 2-3 years
>>>ago) I removed the algorithm (just to satisfy my curiosity) Rebel's
>>>performance in ply-depth decreased with a factor of 2. Surprised by the
>>>outcome I quickly activated the algorithm again.
>>>
>>>Ed
>>
>>Thanks for the sharing your precious experience.
>>In the old gnuchess (IIRC), it wasn't just a piece-square table, but something
>>like the "net result" of the positional evaluation (weak field, king safety,
>>...) had been attributed to the square. Also creation of a doubled pawn for
>>instance resulted in a penalty for this move regarding move ordering.
>>Using solely a piece-square table instead may be a good alternative without
>>serious performance penalty.
>>
>>Uli
>
>How all these ideas would compare to history table?

IMHO, these ideas are completely independent of the history table. Both ideas
can be used simultaneously.

>That seems to work very well for me. It looks like it is incompatible.
>History table is very easy to implement and there is almost no overhead.
>I would recommend this one first to try to a beginner like me.
>
>BTW, I haven't tried too hard, but it looks like killers do not work for me.
>Is that possible?

I obtain slightly larger trees if I omit the killer moves. So, they seem still
to be useful though I guess that they have lost some importance when
transposition tables are present.

Uli

>
>Regards,
>Miguel



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