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Subject: Re: Sort Order for Moves in Full-Width/Quiescence

Author: Don Dailey

Date: 13:50:18 01/28/98

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Hi,

I noticed from my discussions with other programmers that there are lots
of small variations of the same thing.

I have had others claim to use killer captures.  I never store a killer
if it's a capture and consider them a separate class.  My ordering is
basically the same as Stuart's.  Centrality is an improvement I've used
in the past and for some reason have not implemented it.  My program
does not respond to the history heuristic for some reason.   Even this
algorithm has some variations in how it might be implemented which
should be explored.  Do you give each move equal weight or differ based
on distance from root?

- Don


On January 28, 1998 at 13:25:11, Robert Hyatt wrote:

>On January 28, 1998 at 12:30:15, Stuart Cracraft wrote:
>
>>I am curious what others are using for a
>>move selection order in the full-width
>>and quiescence parts of their program's search.
>>
>>Mine has the current following order for full-width
>>
>>	move from the hash table
>>	captures based on MVV/LVA
>>	killer moves
>>	history heuristic
>>	centrality
>
>I handle captures differently.  I look at winning captures ordered by
>my Swap() function, then even exchanges as confirmed by the Swap()
>function, but I stop there.  I defer the losing captures (those not
>chosen by the two above steps) until after killers and history moves.
>
>However, I get a 10% improvement in tree size when using Swap as opposed
>to MVV/LVA with no other changes.  But using MVV/LVA means you can't
>easily
>recognize losing captures and defer them until after the killers and so
>forth.
>
>
>
>>
>>For quiescence
>>
>>	captures based on swap-off routine, ties broken by MVV/LVA
>>	promotions based on promoted piece value
>
>I simply use Swap and ignore ties.  The extra tests you do might
>actually
>hurt.
>
>
>>
>>Notes:
>>  - Doesn't search checks in the quiescence unless the move
>>    happens to be a capture or promotion.
>>  - Doesn't use swap-off to order captures in full-width due to
>>    tests not producing any improvement
>>
>>Thanks for any comments.
>>
>>--Stuart



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