Author: Vincent Diepeveen
Date: 15:57:18 10/04/03
Go up one level in this thread
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.
Of course this all is very expensive but you'll solve any mating trick instantly
now. Be sure to not put dumb limits at your extensions, like so many have a
limit of at most 2 ply, that's no good at all.
>On October 04, 2003 at 18:15:07, Omid David Tabibi wrote:
>
>>I remember that GCP has tried ABC and posted an interesting result of a problem
>>solved quickly using ABC. I wonder whether he is using ABC as Deep Sjeng's
>>backbone algorithm now.
>
>I also remember (maybe we're thinking of the same thing) an instance where he
>solved a problem using a PN2 search in Sjeng, IIRC.
>
>
>>Null move...I think Chess Tiger too.
>
>I don't think Christophe uses null move. At least, if he does, I don't think
>it's the "main algorithm" contributing to Chess Tiger's strength. I remember
May i beg your pardon?
Without nullmove you can go home.
>posts where he said things like, "and that's why Crafty is consistently 100 ELO
>points lower than the top engines," in reference to Crafty using null move,
>which indicates to me that he either doesn't use it, doesn't think very highly
>of it, or he has other things that impact the playing strength to a greater
>extent.
>
>
>>Junior and Rebel use knowledge based extensions/reductions. An especially
>>interesting engine is Hiarcs, which finds some very deep tactical combinations
>>after only a few iterations.
>
>And let's not forget The King, which finds those mate in 20's at ply 1 in zero
>seconds :)
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