Author: Gian-Carlo Pascutto
Date: 13:17:07 09/18/00
Go up one level in this thread
On September 18, 2000 at 15:37:47, Uri Blass wrote: >It is possible that the program will prune lines like 1.xx yy 2.zz tt 3.ww aa >4.rr uu 5.ff because of the fact that 5.ff is not a threat of 3 plies when 5.ff >is an important move because it is a threat of 5 plies and if you search 16 >plies without pruning you will find that 5.ff is good. This is just the same as what happens with standard nullmove. Dynamic nullmove is even better here, because it is more carefull when searching smaller depths. >>Probably true. However Dan is right about the fact that extensions are >>gambling. Sometimes they see it, sometimes they don't. Using a large >>standard search always sees it, save the nullmove/razoring failures, which >>are really small. > >Not extending is also gambling because you can miss a long tactical idea. >I prefer the gambling of extensions and programmers know that extensions are >productive. > >Chess is a tactical game and I am almost sure that 14 plies with extensions are >better than 16 plies without them. I am not so sure. There is a certain depth above which tactical threats get less and less important and positional play takes over. I believe 16 ply to be over that depth. Also, I didn't totally disable extensions, just reduced them. Normal Crafty also reduces extensions if the search goes above a certain depth compared to the nominal depth i.e. it will start getting more carefull extending if it is on ply 32 when the search was only 16 ply to start with. I think this 32 ply may be a bit too much, because of the exponential nature of the search. Almost all programs extensions are tuned to a certain 'expected' ply depth. If hardware continues to improve, I'd be not surprised if people started making programs with less, or smarter extensions. I believe this is necessarry because extensions don't scale well by nature. -- GCP
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.