Author: Mridul Muralidharan
Date: 23:14:40 03/22/04
Go up one level in this thread
On March 22, 2004 at 16:55:23, Dieter Buerssner wrote: >On March 22, 2004 at 12:11:19, Heiner Marxen wrote: > >>I have not yet looked at fruit source, but from my own recollection how >>to do ETC... in Chest I restrict the usage of ETC to non-trivial depths. >>If the expected work without ETC probing is too small, the overhead of >>ETC is does not pay off. May be fruit does restrict it in such a way, >>that even the additional overhead of move make/undo is small compared >>to the potential savings. > >Are you using any search extensions in Chest? I think, this is a real problem >for a normal playing engine. Assume some "mate threat extensions" (decision for >such an extension for example by doing a shallow search after a null move). I >see no method, to keep the extensions consistent for ETC, without doing that >search again. And now, this is not only a makemove, but a real search with many >makemoves ... > >Already keeping normal extensions (that do not depend on a new search, only on >the position and previous moves) consistent seems not easy, for a "grown" >engine, that did not think of encapsulating search extension decisions in a >function, but rather has it all over the place in a long search routine. > >It might still be an idea that works, when some special searches are included to >calculate extensions. > >Cheers, >Dieter Hi Dieter , One of the ideas that I played around with to improve hashtable efficiency was (not sure whether this is ETC itself !) this : Basic Idea : In move ordering , if the hash signature of the resulting position after a MakeMove of this move is already present in the hashtable - increase the move ordering score. Even assuming that this does nto lead to immediate cutoff, you will hopefully get better branching factor since there would be a hashmove from the table that will help you search better. There can be different optimisarion techniques to this to improve its efficiency , when / when not to use it , etc ... but I found the basic idea quiet useful. Mridul
This page took 0 seconds to execute
Last modified: Thu, 15 Apr 21 08:11:13 -0700
Current Computer Chess Club Forums at Talkchess. This site by Sean Mintz.