Author: Antonio Dieguez
Date: 15:10:48 10/20/01
Go up one level in this thread
On October 20, 2001 at 16:17:09, Tony Werten wrote: >On October 20, 2001 at 10:14:24, Antonio Dieguez wrote: > >>On October 20, 2001 at 06:04:54, Tony Werten wrote: >> >>>On October 19, 2001 at 18:41:10, Antonio Dieguez wrote: >>> >>>>On October 19, 2001 at 17:05:37, Tony Werten wrote: >>>> >>>>>On October 19, 2001 at 13:21:55, Christophe Theron wrote: >>>>> >>>>>>On October 19, 2001 at 03:02:28, José Carlos wrote: >>>>>> >>>>>>> Ok. It seems we agree in the background, but disagree in the surface. Software >>>>>>>is much better now, true. Hardware has helped software developement, true. The >>>>>>>point we disagree in can (I think) be said in a line: >>>>>>> I believe that, if Frans would have back then the kind of hardware we have >>>>>>>now, Fritz 3 would be much stronger, much closer to Fritz 7. And for the same >>>>>>>reason, if we had now exactly the same machines as at that time, we couldn't >>>>>>>have done many of the things we do now. That's all. >>>>>> >>>>>> >>>>>> >>>>>>Many improvements in software do not involve having a better hardware, they just >>>>>>involve having time to work on the program, having ideas and having time to >>>>>>implement them. >>>>>> >>>>>>It just takes time to imagine the new search algorithms and to work out all the >>>>>>cases where your evaluation fails. For example it takes time to evaluate better >>>>>>the passed pawns, and I can tell you it does not involve having a better >>>>>>computer... >>>>>> >>>>>>Fritz3 is pretty poor at evaluating passed pawns. Frans did not need a better >>>>>>computer to solve this, he just needed more time to work on the program, and >>>>>>that's why Fritz4 was better in this regard, then Fritz5 was better and so on. >>>>> >>>>>I agree about needing time, but I don't think this is a good example. A couple >>>>>of years ago, memory was quite limited, so no place for pawnhashtables. Without >>>>>hashtables, evaluating pawnstructures is quite a hard job so it was kept simple. >>>>> >>>>>Passed pawns ( with other pawn stuff) is IMO an example of where hardware >>>>>improvements improved the precision of the evaluation, more than just speed it >>>>>up. >>>> >>>>Hi. >>>> >>>>How you do it? >>>> >>>>I don't have implemented yet pawn hashtables(in part because I don't believe >>>>they would help me more than a bit, if), but how do you use it to handle passed >>>>pawns? I suppose you store only the score? >>> >>>No, I just use it to identify some characteristics. >>> >>>>if so, how you do it to not calculate >>>>passed pawns anyway in eval to see if it is obstructed or supported? >>> >>>You still have to do some work, but you can reduce it. >>> >>>My pawnhashtable consist of a lot of bytes where a bit is set if there is a >>>passedpawn, doublepawn, backwardspawn or anypawn on that file. (so 4 bytes times >>>2 colors) >>> >>>This is quite expensive but on average I can take it out of the hashtable 99.9% >>>of the time. So basicly I can do whatever I want in my pawnstructure code. >>> >>>Isolated pawns I dont store because they can be calculated by: >>>onepawn[player] and not((onepawn[player] shl 1) or (onepawn[player] shr 1)) >>> >>>Further I hash the kingsafety left and rigth for both sides,( absence of pawns) >>>and a score if the pawn is defended by other pawn etc. >>> >>>In my pawn evaluation I just and the line of the pawn with the byte to see what >>>kind of pawn it is, then I look for the other stuff. >>>So fe: >>>if passedpawnbyte[color] and (1 shl (pawnfile))<>0 then //check if there is a >>>piece in front of this pawn etc. >>> >>>If kingfile>E1 then safety[player]:=kingsafetyright[player]*weightedmateral >>>if kingfile<D1 then .. >>>else // king still in the middle >>> if onepawn[player] and (1 shl kingfile)=0 then //your on a semiopen line >>> if onepawn[oppo] and (1 shl kingfile)=0 then //even worse it's open >>>etc >>> >>> >>>>by the way >>>>also the material on the board would be hashed?... >>> >>>No, only pawns. Your pawn hitrate would go down too much if you include it. >>> >>>Material is a different hashtable in my program(I have 5 in total) This has the >>>funny sideeffect that my speed on ply 10 is about 5 times that of ply 2-3 ( >>>still filling the tables) on testpositions. In game the difference is smaller >>>but still noticable. >> >>Hi Tony! >> >>Not that I understand all what you wrote, but thanks for taking the time to >>explain! > >Just ask. I'm not a teacher but I don't explaining to interested people. I guess you mean "I don't matter explaining to interested people" :) >>I have thunk about implementing the pawn hashtable but thought that storing it >>only a part of it and also tweaking it later would make my code more messier and >>not faster. > >In my program, filling this table is a different procedure and can be used as a >black box. ok... >>And always prefer to think more time about the eval itself, and also >>exponential improvements, not linear anyway. > >Me too, but at a certain point the exponential ones are finished and you should >go on with the linear ones. the exponential ones finished? I meant the search and killers and prunning and stuff, how can you finish that?? since when Xinix outsearch Fritz? :) I think you mean when you just can't advance via this way then try with the other, and change track next time when you have the same problem again. >>By the way, 5 hashtables... wow :) I have only 2, the eval and the normal, by >>the way I have 59% of ram for the eval one, I know that other programs destinate >>much less for that, well, I hope enough ram is used. > >Way too much. ( My experience, not the absolute truth ) may be. I only tried a small set of positions(just 5!) and set it to search to depth 9 and taken the total time used. Next time I will more and more variated positions. I guess this is the way to test this? is a fact that hashtable data affects search in the next move too in a game but the normal and the eval hashtable as well so I hope this cheap way is enough... Thanks for all and good bye.
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