Author: Uri Blass
Date: 16:22:57 03/05/04
Go up one level in this thread
On March 05, 2004 at 17:30:53, Dann Corbit wrote: >On March 05, 2004 at 17:09:43, Uri Blass wrote: >>On March 05, 2004 at 16:37:16, Dann Corbit wrote: >>>On March 05, 2004 at 16:05:37, Uri Blass wrote: >>>>On March 05, 2004 at 14:18:24, Dann Corbit wrote: >>>>>On March 05, 2004 at 09:12:39, Mathieu Pagé wrote: >>>>>>On March 04, 2004 at 15:25:53, Dann Corbit wrote: >>>>>>>On March 04, 2004 at 15:16:43, Mathieu Pagé wrote: >>>>>>> >>>>>>>>Hi, >>>>>>>> >>>>>>>>I've just change my minimax algorithm for an AB one. (Yes I know i should have >>>>>>>>done this long long time ago, but i did want to keep it simple until it could >>>>>>>>play a complete game and understand _all_ the chess rules). >>>>>>>> >>>>>>>>As expected my engines can search deeper (3-4 more plys) than the old version in >>>>>>>>the same time, but the NPS drop dramatically, going from 3.6M nodes/s to a >>>>>>>>little bit over 2M nodes/s. It's about 44 % decrease. >>>>>>>> >>>>>>>>I think it is normal that the nps of Minimax was greater then AB's one because >>>>>>>>in AB lot of move are generated, but not searched (so they are not add to the >>>>>>>>number of nodes) >>>>>>>> >>>>>>>>but i think that going from 3.6M to 2M is a big difference. >>>>>>>> >>>>>>>>Is this behavior normal or did I put an unusual overhead in my algorithm (For >>>>>>>>now, i have carefully revised my code and can not see what it is) ? >>>>>>>> >>>>>>>>TIA :) >>>>>>>> >>>>>>>>Mathieu Pagé >>>>>>> >>>>>>>How do you count nodes? >>>>>> >>>>>>Each call to AB, I count it as a node. (I have no quiescence or other fancy >>>>>>things) >>>>> >>>>>Then I would expect what you are seeing. >>>>> >>>>>>>Does your perft calculation give a different rate now? >>>>>> >>>>>>No, my perft is as fast as it was (over 4 millions nodes per seconds) >>>>> >>>>>I would not worry about it then. >>>>> >>>>>>>I suspect the difference is that you spend more time in the search and less time >>>>>>>in the move generator. But that is only a guess. >>>>>> >>>>>>I guess you mean more time in the move generation less in the search. did you ? >>>>> >>>>>No. If you spent more time in the move generator, you would be closer to the 4 >>>>>million NPS. You spend more time in the search and call the move generator less >>>>>often. That is generally a good thing. You will see the same thing when you >>>>>strengthen your evaluation, because it will spend more time in eval and less in >>>>>move generation. For an experiment, strap on an evaluation that does nothing >>>>>but count wood. Probably, you will see something very high in NPS like one >>>>>million and stupendous depth. But it will play like crap. >>>>> >>>>>>Note that i still have no ordering except a primitive LVA (without MVV ??) move >>>>>>ordering is the next step on my TODO >>>>> >>>>>Hash next. The most important thing for move ordering is hashing, by far. >>>> >>>>I do not think that it is the most important thing for move ordering. >>>> >>>>I guess that you get more speed by good captures first and history tables and >>>>not by hash after you already have the basic things. >>>> >>>>I do not know about hash when you have nothing but there are many positions that >>>>are not in the hash tables so I do not think that hash alone can be more >>>>productive than what tscp does >>> >>>The most important thing for alpha-beta move ordering is to search the best node >>>first. >> >>No >> >>It is only important to search move that is good enough to produce fail high >>first. > >But if the second move in the move list also fails high? >And the 3rd? >And the 5th? >And the 13th? > >That would be very bad. In that case there is not going to be a big difference in the tree. With pruning like null move there are good chances that best move is going to generate a smaller tree but we are not talking about a program that has null move or different pruning. Uri
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