Author: Vincent Diepeveen
Date: 04:53:45 03/26/02
Go up one level in this thread
On March 25, 2002 at 18:41:52, TEERAPONG TOVIRAT wrote:
>
>Hi,
>
>I've a few questions.
>
>1. When we extend searching depth,which one should be
>stored as hashtable->depth depth or depth+extension?
>
>
>Search(alpha,beta,depth)
>{
>
>Probehash()
>if(check) extension+=...
>
>-Search(-beta,-alpha,depth+extension-1)
>
>Storehash() => here with depth or depth+extension ???
>
>}
this position is from depthremaining = depth, so obviously
you are forced to store depth here.
the reason why it works better is transpositions!
the right word here is extend *after* you escape from a check,
don't fiddle with search depth before you escape from the
check. obviously don't add extra depth for no reason too to the
depth to store in hashtable. it is not correct and not working
either.
>
>2.After I add Extended Futility Pruning,cutting off at prefrontier
>nodes, to my program,it miss mate in 1.
>How to fix this?
Do without futility, where do you need it for?
Just write some chess specific code which moves to try in qsearch.
At normal search depths forward pruning shouldn't be rewarding.
>3.Recapture extension makes my program much slower.
>How much benefit do we gain from it?
Throw them outside. nowadays hardly anyone can use them.
the reality is that if you do near to shit in qsearch (futility,
lazy eval and such) and
forward prune a lot last few plies, that recaptures seem
not a major problem to now and then to extend.
for sure if you have a pretty consequent search near the end
of the search, you can do without.
>Thanks for any comment,
>Teerapong
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