Author: Dieter Buerssner
Date: 15:12:24 06/04/04
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On June 04, 2004 at 17:59:01, GeoffW wrote: >However when I went on to test this mod. it was significantly worse then before >? Same experience here. Allways replace (with a normal simple scheme, and a hash table, that can only store one score/bound/depth/draft per position) seems just better, than a depth preferred replacing scheme. My explanation: you will keep with a depth preferred scheme some useless entries too long. Window bounds changed inbetween. You keep that deep lower bound entry, that is basically worthless with the new window bounds. An upper depth entry would be nice, and possibly good for a cutoff. But you have already that lower bound entry with deep depth, that is useless - and difficult to overwrite. Sure, not a very scientifical description of what happens. I think, especially in real games (not just test positions, and with pondering) overwrite always will win vs. depth preferred. Of course, there are various ideas possible (and certainly implemented) to have a compromise. For example, one table, that will be overwrite always, and another one, that will be depth preferred. In reality, this can be easily be in the same table (and therefore will be more cache friendly). Just for example have for each position two entries. One, you will alsways overwrite, independent of depth, and the other one, you will only overwrite, when the new depth >= the already stored depth. Many people use the term "draft" instead of "depth", in my reasoning. Regards, Dieter
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