Author: Rafael Andrist
Date: 02:40:56 04/24/01
Go up one level in this thread
On April 24, 2001 at 03:57:54, Tony Werten wrote: >On April 23, 2001 at 11:12:55, Rafael Andrist wrote: > >>In my chessprog, I'm using an Alpha-Beta-Search with an infinite window. After >>adding a hashtable, only half of the nodes need to be searched, but I get still >>a branching factor around 9. The use of Iterative Deepening didn't change much. >>So now my question is what can I do to improve the search? Should I try to >>improve the move-sorting? Or is it necessary to use other pruning techniques >>like Nullmove? > >The use of iterative deepening doesn't nescesairy help the BF. It's advantage is >that you don't need to decide on forehand how deep you are going to search. > >If you decide to search 10 ply and you run out of time, without ID you have >nothing, with ID you have the best move of ply 9. I know, but I hoped that it helps sorting the moves too. It really does that too, but only a little bit. > >BF of 9 is a bit too high but not too much if you don't use nullmove. There are >a couple a reasons why it could be this high: > >Are you using killermoves ?(you should, noncaptures only) Now I do :) and the BF has gone to 7. >Is your evaluation a bit intelligent ? (it should, at least material and passed >pawns) Yes, my eval is little bit intelligent, I get good results in games with fixed dephts. >Do you store bestmoves in the hashtable (you should) ? Yes. >Do you store bestmove if score is <=alfa ? (you shouldn't) No. Why is this bad? >How do you orden capturemoves (to start with, use MVV/LVA, most valuable victim, >least valuable attacker ) >Have you tried history tables ? (should help at lower depths ) > my move ordering: - Hashmove - 2 Killers (just implemented) - checking moves - capturing moves (sorted like you discribed above) - history heuristic - castling (if there are moves with equal scores, castling should be favoured) - moving piece (pawns first, king last) - square onto which the piece move (center, near the opponent is good) The history heuristic doesn't seem to work well, I may have to improve this too. Thanks Rafael B. Andrist >Have fun trying out, > >Tony >
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.