Author: Sergei S. Markoff
Date: 03:30:13 10/22/03
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. 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? Best wishes, Sergei
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