Author: J. Wesley Cleveland
Date: 17:43:30 12/06/00
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On December 06, 2000 at 12:45:30, Leen Ammeraal wrote: >I have the impression that most chess programmers >use their hashtables to store >only one evaluation value, along with a flag >denoting Lower, Upper, or Exact. >Why not store both a lower and an upper bound, >where lower = -inf or upper = +inf if only one >real bound is available? A flag is then >superfluous, since this follows from >the two bound values. >For example: >LB UB Flag value (not stored) >-inf 100 Upper >-20 +inf Lower >30 30 Exact >This also offers the possibility to store >two different bounds at the same time, as in >LB = -50, UB = 70. There may be a problem here. What do you do when you have a upper bound and a lower bound with different depths? Crafty appears to store these in two different hash table entries. >This is the way I do it, but, unfortunately, >my program is weaker than most others. >Could this be because this idea of storing >two bounds and no flag is wrong? >Leen Ammeraal
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