Author: Will Singleton
Date: 16:27:00 04/10/02
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On April 10, 2002 at 16:38:49, Gian-Carlo Pascutto wrote: >On April 10, 2002 at 00:27:54, Keith Evans wrote: > >>When Hsu designed the move generator for Deep Blue he added extra hardware so >>that he could generate checking (even discovered checks) and check evasion moves >>more quickly than his first move generator could. (Compare the diagrams for the >>square transmitters and receivers in the IEEE micro article to those in his >>thesis and to those describing the Belle generator.) He could have generated >>these moves without the extra hardware and design time by iterating through >>moves and throwing away moves which didn't meet the criteria, but apparently he >>thought that the performance of the move generator was important enough in these >>cases to justify adding the complexity. >> >>What's the general opinion on this? Was this time well spent, or was it a waste >>of time? I searched for information on what programs typically do during qsearch >>and couldn't find much of anything directly related. It seems like he would have >>simulated this before commiting to design, and perhaps discussed it publicly >>with some top programmers. > >In the qsearch, being able to generate only capture moves fast is >a nice speed advantage. If you want to do checks/check evasions too, >you'll have to generate these moves somehow. If you have to fall >back to your standard movegen, that'll come with a speed loss, so >it makes sense to try to avoid that. > >Since qsearch tends to amount to a large % of the nodes searched, >this sounds like an understandable decision. > It's possible that a large reported qsearch is either the result of counting nodes differently than other progs, or doing checks, or both. I count nodes in make_move, and test for checks only in the first ply of qsearch, which results in about 50% qsearch vs internal nodes. It's odd, but I think if people aren't aware of differences caused by how nodes are counted, they may spend time trying to fix things that aren't broken, or vice-versa. Will
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