Author: Omid David Tabibi
Date: 20:35:00 10/04/03
Go up one level in this thread
On October 04, 2003 at 23:08:23, Uri Blass wrote:
>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.
But what about doing the above only in the first ply of quiescence?
>
>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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