Author: James Robertson
Date: 10:20:48 08/24/99
Go up one level in this thread
On August 24, 1999 at 10:05:53, Inmann Werner wrote: >On August 24, 1999 at 09:57:43, Robert Hyatt wrote: > >>On August 24, 1999 at 05:39:54, Inmann Werner wrote: >> >>>Hello all! >>> >>>I am again trying to tune my program, and came to some questions. >>> >>>1) >>>What to do with fail lows and hashing. >>>Put them in for move ordering? I think no. >>> >>>Put them in for hash hits? >>>I do, but I am not sure, it is good. >>>If I get a hash with fail low flag I check, if it is again a fail low and only >>>then I use it. >>>That makes a cuttoff for easy, not disturbing? >>>But in positions, i get differences, if I use fail low hash hits. Not much, >>>but...? >>> >>>What do you think about doing best? >>> >>> >>>2) >>>It disturbed me, that in some not clear positions the search often switches, and >>>that only for 1 point better (1/100 pawn) which is not real relevant, but costs >>>much time cause of the research. >>>So I thought about making the eval result not so perfekt (score=(score/2)*2). >>>Now it switches not so often, but in "normal" positions needs more nodes (less >>>cutoffs?). >>> >>>Is this idea dumb or worth thinking about it. >>>Makes a small evaluation, where much values of different positions give the same >>>value the search slow? >>> >>>Werner >> >> >> >>I don't quite understand, but you have only three cases to handle: > >Yes, I have always problems to say my problems in English :(( >> >>1. When you complete a ply, and the score you found was > alpha and < beta, >>you store the score, and EXACT. If you later get a 'hit' and find this >>position, assuming the depth is sufficient, you just return value without >>doing any more searching at all. >> > >Clear! > >>2. When you get a fail-high at a node, you store the value you got (which was >>>= beta) along with a flag LOWER (to note that this is a lower bound on the >>score, that it might actually be higher than this). When you get a hit on this >>type of entry, you only need to verify that your current beta value is < the >>bound stored in the table, and if so, you return the table value without >>searching further. >> > >clear! > >>3. When you get a fail-low at a node, you store the value (alpha or less) >>and a flag UPPER (this is the best you can do, the worst score possible could >>be even lower). When you get a hash hit, and your current alpha value is > the >>table bound, you just return the table bound with no further searching. >> >>That's all there is to it... > > >Then you say, fail-low = UPPER entrys in hash should be used for hash probes!? > >My question. Should these entries also be used for move ordering? > >Werner How do you use hash entries for move ordering? Does it help? James
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