Author: William Bryant
Date: 15:26:42 08/27/00
Go up one level in this thread
On August 27, 2000 at 17:33:15, Tom King wrote: >Hi all, > >a question for programmers on fail highs. > >what do you do in your program if a fail high is encountered, which on the >research fails low? > >I've ignored this issue, because it doesn't seem to happen all that often (in my >program). So if my program finds a move which fails high, even if the research >indicates that it maybe shouldn't have failed high, it thinks the move is good. >Maybe this is bad? At the WMCCC recently, I noticed a couple of these fail high/ >fail low moves cropping up at critical, complex positions. Often I was unhappy >with the move my program chose in these cases. Perhaps these fail high/ fail low >moves need to be treated with suspicion? > >Cheers, >Tom Tom, I've had the same problem and asked the same question. Here is a nice detailed explination that I saved, posted here about a year ago. The original poster was Bob (Dr. Hyatt). " A root move fails high, but then fails low on the re-search. I keep the fail-high move. You can probably eliminate the fail-low by simply searching with -inf,+inf, but it will be slower, and due to hash overwrites/draft problems this fail-high/fail-low problem will happen without this large window. And with the large window you might fail high on bound X, but get a score back that is < X ... It is mainly an artifact of null-move search and hashing..." Hope this helps. I keep the move, and go onward to the next iteration... William wbryant@ix.netcom.com
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.