Author: Uri Blass
Date: 20:08:23 10/04/03
Go up one level in this thread
On October 04, 2003 at 22:22:33, Omid David Tabibi wrote:
>On October 04, 2003 at 18:57:18, Vincent Diepeveen wrote:
>
>>On October 04, 2003 at 18:40:08, Russell Reagan wrote:
>>
>>Just put next in your engine:
>> - checks in qsearch at the first ply (or when you already did them
>> just stick to what you did now; in diep i do them at any ply in qsearch
>> btw, but most have problems controlling that so i do not mind it if you
>> just try 1 ply)
>> - nullmove search with window alfa,beta = -mate+1000,
>> so you'll find 100% sure a mate threat
>>
>> - if you see a mate threat you extend that position by 1 ply and store
>> in hashtable this position got a mate extension.
>>
>> - now you extend moves double sometimes. So recapture that gives extension,
>> you extend. If the same move also gives opponent a check, another extension.
>> So you can extend 2 plies then.
>
>2 plies extension at once? What if you detected a mate threat and played a move
>which is a recapture and also checks the opponent? Extend by 3 plies?!
>
>Seems a little frightening! But will try it tonight...
>
>Looking at Fritz's parameters, the default values are selectivity=2, and
>futility pruning activated. So, we can assume that Fritz is using R=2. However,
>looking at its analysis it rapidly reaches very deep while not ignoring any
>significant tactical threats. That's also the case with Shredder, which uses
>selectivity=-1 (it is not a typo, -1 ?!) and futility=2.
>
>Falcon's tactical strength is somewhat superior to that of Crafty, but comparing
>it to other null-movers, Fritz and Shredder, it is way behind in tactics...
>
>BTW, when in quiescence you detect that one side is in check, do you do the
>following:
>
>int quiesce(int alpha, int beta) {
> ...
> if (checked)
> return search(alpha, beta, 1);
> ...
>}
No
This is going to allow very long check escape sequences because my qsearch look
for checks of the side to move at least in the first plies.
Everything is done inside the qsearch and if enough plies were done in the
qsearch I do not extend checks.
I have a special function qsmall and when I get there checks that are not
captures are not considered and after some plies there even reply to checks are
not considered.
Uri
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