Author: Heiner Marxen
Date: 21:11:12 11/22/01
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On November 22, 2001 at 19:41:30, Robert Hyatt wrote: >On November 22, 2001 at 15:52:22, Uri Blass wrote: > >>The times of my program in calculating perft(number of legal games of fixed >>number of plies) are not bad. >> >>I get on p800 33 seconds for finding perft 6=119060324 in the initial position >>and also 33 seconds for finding perft 5=193690690 in another known position >> >>this is not a mistake and my program needs similiar time because it generates >>only legal moves so it needs less nodes to calculate perft 5. >> >> >>[D]r3k2r/p1ppqpb1/bn2pnp1/3PN3/1p2P3/2N2Q1p/PPPBBPPP/R3K2R w KQkq - 0 1 >> >> >>I am interested to know what is the speed of the best free or commercial program >>in calculating perft. >> >>Yace is the fastest free program that I know. >>I do not know about a commercial programs with this function. >> >> >>My move generator is not 100% correct because it has some probelms with the en >>passant rule that I did not care to fix but it finds the right numbers and it is >>clear that fixing the errors is not going to change significantly the speed of >>the program. >> >> >>yace is slightly faster than my program in caculating perft 6 in the initial >>position(32 seconds) but has no chance in the second position and I plan to >>improve the algorithm(there wer important things that I did not do because of >>more important things). >> >>The main improvement that I worked about in the last days was improvement in >>generating moves(my previous version generated only piece go to square when I >>started from the target square and now I start from the piece except checks). >> >>second improvement that I found was a mistake of generating move twice when I >>did not need to do it. >> >>I calculate perft 4 in the following ways: >>1)generate all legal moves >>2)make a3 >>3)generate all legal moves >>4)make a6 >>5)generate all the legal moves >>6)make a4 >>7)generate all the legal moves and add their number into perft > >The original idea behind perft was to measure move generation _and_ make/unmake >speed. IE if you do perft 4, a program would generate and make every move up >to 4 plies deep. > >You are cutting off the last ply of make/unmake, which is ok, but it isn't >comparable to the original intent of this. Otherwise everybody will go faster >by dumping the last layer of make/unmake which is expensive... While I do understand your original intent (do I?), I have objections: that way the resulting number is as meaningless as every other NPS number, i.e. comparable between different versions of the same program, but not at all between different programs. On the other hand, computing that exact resulting number (from perft) is a well defined job. Yes, it has not much to do with the normal job of a chess program, but it really _is_ well defined. Computing it, just that number, is quite independant of the methods and circumstances to generate moves and to do/undo them in any program. Hence, it is a candidate for a number to be comparable among different programs. IMHO. Back to the facts... here are my numbers from Chest. I do not execute the last ply, just count the number of moves in the generated move list, which does contain just the legal moves. Also, executing a move in Chest is expensive, and prepares the next questions/functions which may follow. I do this on a K7/600 (without any hash table). From the initial position: FEN: rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - Counting width of legal tree, 6 plies deep... Time (user) = 40.57 sec dep #nodes quot sum nodes 0 1 [ 0.000] 1 1 20 [ 20.000] 21 2 400 [ 20.000] 421 3 8902 [ 22.255] 9323 4 197281 [ 22.161] 206604 5 4865609 [ 24.663] 5072213 6 119060324 [ 24.470] 124132537 The other position provided: FEN: r3k2r/p1ppqpb1/bn2pnp1/3PN3/1p2P3/2N2Q1p/PPPBBPPP/R3K2R w KQkq - Counting width of legal tree, 5 plies deep... Time (user) = 41.12 sec dep #nodes quot sum nodes 0 1 [ 0.000] 1 1 48 [ 48.000] 49 2 2039 [ 42.479] 2088 3 97862 [ 47.995] 99950 4 4085603 [ 41.749] 4185553 5 193690690 [ 47.408] 197876243 At least, we agree on the resulting numbers :-) Cheers, Heiner
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