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Subject: Re: Foregoing positional eval in qsearch

Author: John Scalo

Date: 16:29:59 11/20/97

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On November 20, 1997 at 19:12:54, Edward Screven wrote:



>On November 20, 1997 at 18:49:17, John Scalo wrote:

>

>>Q- Is it acceptable to run through the qsearch without ever evaluating

>>the position? In other words only the material balance is considered. It

>>sure is a lot faster and most positional eval's don't include a term

>>worth more than half a pawn. But there are some obvious dangers such as

>>ending up with a king in the middle of the board open to attack, etc. I

>>suppose it's a tradeoff of speed/quality of play. Is the speed worth it?

>

>i tried this once.  my program not only played worse, but it scored

>lower on test suites.  but you should try it for yourself -- it should

>be easy to implement.



I'm actually moving in the opposite direction -- I currently do not
consider the positional eval and I'm considering doing so, but not
looking forward to the speed hit.



>

>i think a better direction is to work on forward pruning to reduce your

>branching factor.  for example, do you use a static exchange evaluator

>to nick losing captures?  how about razoring and futility cutoffs?

>also, you might try lazy evaluation.

>



Yes in some part to all of these, except for the s.e.e. I currently sort
by capture net gain (i.e. pawn takes king goes first, king takes pawn
goes last). I'm looking for pointers on doing a s.e.e. for better
sorting but my use of bitboards is currently limited and I understand
this is a critical tool in making a fast s.e.e.



Thanks,

-j



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