Author: Vincent Diepeveen
Date: 23:25:44 07/20/99
Go up one level in this thread
On July 20, 1999 at 23:57:13, Dan Homan wrote: >On July 20, 1999 at 20:35:49, Vincent Diepeveen wrote: > >>On July 20, 1999 at 11:25:07, Dan Homan wrote: >> >>>On July 20, 1999 at 08:52:18, Vincent Diepeveen wrote: >>> >>>> >>>>Let's however write down some facts why my prog is unhappy with MTD. >>>>It's up to others to generalize it to their progs: >>>> >>>> - the huge number of researches needed. In DIEP my evaluation is nowadays >>>> in 1/1000 of a pawn. For a long time i had 1/200 of a pawn (in the time >>>> i experimented with MTD), but now i have 1/1000 of a pawn. So a drop >>>> of 0.20 pawn, which is a normal drop in DIEP, is in fact a drop of 200 >>>> points. Happy researching! >>> >>>Even if the score dropped a whole pawn (1000 points in DIEP), this would >>>only be 10 or 11 zero-width searches (2^10 = 1024) assuming that you >>>bound the score in an efficient manner. Also, I can understand having >>>a high resolution within the eval routine itself, but does it really help >>>to have the output of the eval be in 1/1000 pawn units? I wouldn't trust >>>the sum total of any eval routine to 0.001 pawns! Maybe you could >>>output the total eval in units of 1/100 of a pawn (or even less). >>> >>>Actually, that is an interesting question. Does anyone know what the >>>optimum eval unit is for searching? I am talking here only about what >>>the eval outputs - not the unit used internally for calculating the eval. >>>I know that most programs use the same unit for both purposes, but I >>>wonder if that is really optimum. >> >>Every time i get to a draughts tournament i have to laugh a little when >>playing a certain program. It has a stone at 1000 points worth, >>yet he has no positional eval in 1/1000 of a stone. Only in 1/10 of a >>pawn. So he's either at +0.100 or -0.100 or a multiple of that. >> >>If you only count material in chess >>you can of course simply use 10 for a pawn. >>a pawn = 1, knight=3,bishop = 3, rook=5, queen=10 >>and you're ready. MTD will rock i bet. >>Start with window 0 from root, >>and end the game with a window -100. >> >>Hope that answers, as your question is kind of retoric. > >My question was serious. I have a way of going from one idea >to another - sorry about that. I started by pointing out that >you didn't need to do as many researches as you thought, to >wondering what benefit you got from using 1/1000 of a pawn >during your search, to the general question of whether it >is a good idea to use different eval resolutions internal >to the eval routine and when you return a value to the search. > >I wasn't suggesting anything as crazy as setting the eval >resolution as coarse as one pawn. What I was curious about was >whether the search was improved by having you eval output results >in 1/1000ths of a pawn. I can understand the benefit of having >1/1000 internal to the evaluation routine - this way small >positional benefits can add up to something significant, but >might is it useful to return the value to the search with >less resolution than 1/1000th? Do you see what I mean here? > >Lets say the eval works in 1/1000 units. Add all the scores >up for pawn structure, king safety, piece placement, etc... Now >we have a total score in 1/1000 units of a pawn, but do we trust >this total score to this accuracy? Should we return this raw score >directly to the search or should we round it down to 1/100 of a pawn >or perhaps even less? Is there benefit in keeping the 1/1000 >resolution when we return the total score to the search? Is there >benefit to the searching routines in rounding the score down to a >coarser resolution? > >I don't know the answers to these questions. I tried it briefly with >my program (which works in 1/100 of a pawn normally) by simply >bit shifting the eval result so the resolution was 1/25 of a pawn. >I noticed a (small) speed-up in the search, but I worried that this >resolution was too coarse and took the changes out. before my eval returns to the search i can obviously lose knowledge by shifting my score of 1000 pawn units to 10 pawn units, but it won't play well then. Idem for 100 > - Dan > >> >>Sorry to bother you, forgot the name of your program and the number of >>nodes a second you get with it. >> >> >> >>> - Dan
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