Author: Inmann Werner
Date: 07:05:53 08/24/99
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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
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