Author: Dann Corbit
Date: 16:20:08 06/25/04
Go up one level in this thread
On June 25, 2004 at 19:11:34, Stuart Cracraft wrote: >On June 25, 2004 at 17:46:37, Dann Corbit wrote: > >>On June 25, 2004 at 16:55:47, Stuart Cracraft wrote: >> >>>On June 25, 2004 at 16:46:31, Dann Corbit wrote: >>> >>>>What is your branching factor? >>>> >>>>The best programs have a branching factor between 2 and 3. >>>> >>>>If you already have a branching factor in that range, do not expect any more >>>>really dramatic speedups. >>> >>>This seems like a very useful measure to implement but I am not >>>sure how it might be done. >>> >>>Take the # of total legal moves searched at each node (prior >>>to cut) and divide by the total number of nodes searched across >>>all nodes? >>> >>>Time between iterations in mine goes up about 2x >>>to 6x per iteration but this is obviously a different measure >>>than what you are suggesting. >> >>That is close enough. Look at the deeper plies to see what sort of time ratio >>you are seeing. >> >>If those average around 2-3, there is not a huge amount of fat to trim. If they >>average around 5-6, then you will still see some huge speedups. >> >>Are you using a pvs search? That cuts a lot of nodes. >> >>IID gives better move ordering and sometimes cuts nodes because of that. >> > >What is IID? I have iterative deepening... Internal iterative deepening. http://www.chessbrain.net/beowulf/theory.html >>Without knowing what techniques you are using, it is hard to speculate about >>what sort of speedups you might see. > >Yes I use PVS though currently the pv is not searched first and I wonder >how much that will help. However, the best move found by the previous >iteration is searched first on the next iteration as a very >cheap approximation. Eventually I will walk the transposition table for >the PV. > >Briefly, it has: >o iterative deepening (hash table not cleared through iterations) >o history heuristic (thank you Jonathan) >o 1-tier 1M entry transposition table (algorithm: replace-always) >o null move with reduction factor R=3 >o quiescence search all caps MVV/LVA (no SEE though) SEE will probably help a lot. >o extensions: move in capture search to get out of check >o evaluation - just pc/sq at the present. > >There are no other search extensions, no fractional, extensions, no >futility, no razoring. > >So that's it. Bare bones. Just looking for big things I've missed >that won't take an arm and a leg to implement before the real >research can begin. Looking for double-digit improvement possibilities >that remain, if any. What is your fail high percentage? If it is below 90, then you can have a large improvement in fewer nodes searched by better move ordering. >I wonder if searching the PV first instead of just the PV's first move >first would make a big difference. Probably so. Can't think of much >else on my own presently. I assume that you use an aspriation window? It looks like most of what is left for improvment could be through razoring or other frontier pruning types of ideas. But they have danger, of course. What is your NULL MOVE set to for reductions?
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