Author: Ed Schröder
Date: 06:34:32 08/16/03
Go up one level in this thread
On August 16, 2003 at 09:24:42, Uri Blass wrote: >On August 16, 2003 at 09:13:25, Ed Schröder wrote: > >>On August 16, 2003 at 03:24:47, Johan de Koning wrote: >> >>>On August 15, 2003 at 04:03:32, Gian-Carlo Pascutto wrote: >>> >>>>On August 15, 2003 at 02:03:28, Johan de Koning wrote: >>>> >>>>>The job of an engine is to search a position, >>>> >>>>The goal of an engine is to play chess games. >>>> >>>>A user may use it to analyze positions. In that case, not being >>>>able to remember analysis when moving throughout the variations >>>>is a weakness, not a strength. >>>> >>>>>and the result should depend only >>>>>on that position. Like the power of a car engine should depend only on its RPM, >>>>>not on how fast the car moves or how fast the car moved 1 minite ago. >>>> >>>>Power doesn't mean anything. It's an internal parameter >>>>that only indirectly relates to real world performance. >>>>Acceleration or speed does. They do depend on past situations. >>>> >>>>>Sticky TT (or reorderd piece lists :-) cause the engine to have a mind of its >>>>>own. Things with a mind of their own, like cats and (wo)men, are unreliable and >>>>>don't make a good tool. >>>> >>>>You sound like a kid that believes in Santa Claus. >>>> >>>>Nondeterminism is something you can live with. Forget about getting >>>>the engine working on multiprocessor if you don't. >>> >>>So far you sound like someone trying to mimic Vincent. :-) >>> >>>I listed predictability as the first of 7 reasons to clear the TT. I did not >>>list any reasons to preserve the TT, though they do exist (else there wouldn't >>>be any discussion). >> >>But he wants to hear the 8th reason :) >> >>Here is my guess, you are marking all kind of positions in the HT to extend that >>position the next time (iteration). It's the reason why you can not afford to >>have a big HT and why you must clear it, otherwise the tree would explode. >> >>Am I close? >> >>Ed :) >I do not understand the reason that you give. > >I see no reason that you have to mark all position in the hash tables and >I see no reason to extend all positions in the hash tables for the next >iteration. Singular Extensions comes to mind, you mark a move as singular in the HT and search it 1 ply deeper the next iteration. There are plenty of other possibilities, dangerous pins, threats, mate threats, or any other information you can extract from the search paths. Ed >I also do not think that big hash tables influence the extensions decisions >in a negative way and I guess that it is possible to check it by comparing >chessmaster with 256 mbytes and chessmaster with smaller hash tables(I will be >surprised if 256 mbytes make chessmaster significantly slower at 120/40 because >of extensions). > >Uri
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