Author: Sune Fischer
Date: 09:55:58 01/20/04
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On January 20, 2004 at 11:55:20, Robert Hyatt wrote: > >OK. Multiply the above by 100x and turn that into times. It takes how long >to copy a complete cache line from memory to cache and back? That is 32 words >which is longer than _most_ PVs. Do that 100 times you can't even measure it >over the rest of the search expense. :) You are not adressing the other issues, the termination stuff and the added code. It's not the copy-cost that mainly keeps me from doing it. >>The fundamental principle in chess programming is never to do any work that is >>not needed. >>That's why I think it is a bit silly to update a PV a few hundred times (in >>particular in qsearch) and then only print it out the last one. >> >>If you need the pv for search related things I can understand, but if you only >>want it to look at it then it is nothing more than eye-candy. > >Sorry, but we disagree. A chess engine has more than one function. If all it >did was play chess, then I'd get rid of the PV myself although I might change >my mind based on move ordering. IE at the end of an iteration I stuff the PV >into the hash to make sure there are no "fishy" moves left there, and not doing >that will impact the search space a bit. Doesn't that worry you then, that you have to do this at all? It might be an indication something isn't optimal if your hash is losing important entries that easily. >But a chess engine does other things. IE analyze positions and give scores and >PVs for the moves. Who would want an annotated game that just suggested a move >and score, with no indication of why the move played was bad or the move >suggested was good? I'm not sure you will care for my opinion on the value of computer annotated games :) Speaking as a chess player, I think there are better ways to analyze a position than to look at a PV. Just consider how often the it fails to guess the right ponder move, that's like 40% of the time perhaps? Now what's the probability it can guess the 3rd move correctly? It turns into nonsense real fast, so for a serious player it can't be of much value. >And, again, what about debugging? Right, nothing debugs the hash better :) -S.
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