Author: Leen Ammeraal
Date: 05:50:55 03/05/01
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On March 05, 2001 at 08:29:28, Bas Hamstra wrote: >On March 05, 2001 at 07:26:28, Leen Ammeraal wrote: > >>I understand that it is usual to have at most >>one entry in a hashtable for a given position. >>Clearly, an entry with a higher (depth) draft >>should replace one with a lower draft, >>while a new candidate with a lower draft >>should be ignored. >>Therefore, in the rest of this discussion, >>let us assume that the draft >>of the existing entry is equal to that of >>the entry that may replace the older one. >>It seems clear to me that a tighter bound (higher >>value in the case of LOWER and a lower value >>in the case of UPPER) should have precedence. >>If a lower bound has been stored and >>the new candidate is an upper bound >>with the same score, then I replace the LOWER >>flag with the EXACT flag. >>The situation is similar with lower and upper >>exchanged in the last sentence. >>But what if these scores are unequal? >>Is a lower bound more valuable than an >>upper bound, or is it the other way round? >>Remember, we are talking about equal draft, >>unequal scores and one flag being LOWER and >>the other UPPER. >>Leen > >What I do in case of equal draft is simply replace the older one, without any >further consideration. Almost all records are bounds. Purpose of alphabeta is to >move alpha up and beta down, until they intersect. Basically it's the same >thing. One important difference, though, is that LOWER type hashrecords have a >useable bestmove and UPPER type not. > > >Bas. The last sentence of your answer may be very important in relation to move sorting. I will change my program accordingly. Thanks. Leen
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