Author: Vincent Diepeveen
Date: 10:13:37 10/22/03
Go up one level in this thread
On October 22, 2003 at 06:30:13, Sergei S. Markoff wrote: >Hello All! > >DS - is a term for using some features of classical evaluation that consists of >two parts - material and positional. >There are a lot of positions in that for one side material evaluation is >0 but >positional evaluation is <0 or vice versa. The root of big part of mistakes made >by modern engines is underestimating of positional eval because the positional >evaluation is constructed of several "atomic" factors. The _sum_ of this factors >frequently isn't good positional evaluation (anyway there are a lot of >"palliative" methods to avoid this problem like evaluation the relationship >between several factors). We can't fully trust positional evaluation and that's >why most of modern programs using a small values for a lot of factors. In 1990 your statement would have been true. However in 2003, i know very little modern programs with small values for the positional factors. Perhaps diep is one of them in some sense, yet the quantity makes the total positional score overrule any material reality. >The idea of DS is to use disagreement between positional and material >evaluation. There are a lot of ways how to use it. For example we can check >nodes in which sum_eval < alpha, but positional eval is large (for example we >sacrificed a pawn for attack e.t.c.). For this nodes we can: >1. Rebuild quiescence to include checks e.t.c. >2. Extend search >3. Change eval for the case of losing pawn or quality (trade bishop or knight >for rook) for big passed pawn / king attack eval. >4. Do assymetric eval. >5. Something else? > >Do you have some ideas in this area? In case you forgot, the evaluation can just return 1 score and that's a total score it can't return 2 scores for either positional or tactical matters. The reason for this is somehow you must combine at some point in history the 2 scores to trigger a decision. Using those decision rules you can just as well return 1 integer score. Best regards, Vincent >Best wishes, >Sergei
This page took 0.01 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.