Author: Robert Hyatt
Date: 15:14:23 08/19/98
Go up one level in this thread
On August 19, 1998 at 08:43:30, Don Dailey wrote: > >>you might need some GM analysis. IE a couple of years ago, Roman called >>me one morning and said "Bob, I have played hundreds of games against >>crafty over the past month or so, and I've found one major problem that >>is hurting it... you apparently have too large a bonus for keeping the >>bishop pair." I was surprised he even knew what this was all about, but >>listened, and he went over some games and explained what was going on. I >>lowered the bonus... and he played some more and said "nope, still too high" >>as it will allow itself to get into a really ugly position rather than >>trade a bishop for knight. I kept reducing it until finally "this is >>right now... it keeps the pair when possible, but won't accept gross >>positional penalties to do so." >> >>The number he liked was .2, or 1/5th of a pawn... and over the next month >>or two I would bump it up and he would complain. I've left it there ever >>since... > >This makes sense to me. How does your basic bishop compare to your >basic knight? As I stated before, I sometimes wonder if a high >bishop pair bonus is ok, as long as you have compatible positional >terms? .2 might be right for your program, but maybe not for mine? >It may be we have to consider what typically happens during an >exchange of knight for bishop. Quite often a doubled pawn is >created, sometimes this is around the enemy king, other times >a majority is gained etc. The values these other terms have might >be a factor. > >We have a pretty high bishop pair bonus and sometimes we do give >up too much for it. It's all a bit of a black art isn't it? > > > > the numbers are pretty dynamic, but are roughly 3.3 each to start with, although a bishop on an open board is more like 3.6... Of course a knight can reach that value too if it is stuck in a hole (at e5, for example)... >>>I also do not believe 2 bishops = 2 knights + 1 pawn but a couple >>>of strong players (much stronger than me) have told me this was >>>not unreasonable. >>> >>>- Don >> >>I don't believe this either. In some cases, yes... but with all pawns >>on the same side, the two knights can actually be better, since they can >>gang up on a single weak pawn while two bishops can't...
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.