Author: Peter McKenzie
Date: 03:31:59 06/20/01
Go up one level in this thread
On June 20, 2001 at 05:26:48, Daniel Clausen wrote: >Hi > >On June 20, 2001 at 04:36:44, Uri Blass wrote: >>I use the perft command in crafty in order to debug my move generator. Good to hear you are writing a chess program Uri, you'll have alot of fun! >> >>I found that perft 4 gave me correct result when perft 5 does not give me >>correct result and I got 4865621 instead of 4865609. >> >>After finding it >>I calculated the perft 4 after every legal move and found that perft 4 does not >>give correct result after 1.d3 >> >>After finding it I checked perft 3 after d3 to see where my program is wrong >>and found that after 1.d3 c5 I got 15972 instead of 15971. >> >>I now need to continue in this way to check where is the error. > >Personally I found the position/numbers given in KiwiPete's finger notes on CCC >to be extremely useful to debug my move generator: Nice to hear that someone still finds that useful! > > 6: The following position is a move generation test. Listed are the number > of different games from that position to ply 1,2,3,4, and 5. > 7: r3k2r/p1ppqpb1/bn2pnp1/3PN3/1p2P3/2N2Q1p/PPPBBPPP/R3K2R w KQkq - > 8: 48; 2,039; 97,862; 4,085,603; 193,690,690 > >The position includes all move-types I could think of, which the initial >position obviously doesn't. (ie promotion, castling after 5 plies) Obviously a >'setup position' feature is needed to use this though.. Yeah, I wanted a position where all the funny moves would come up within a few ply. > > >>Is there a faster way to debug the move generator? Plenty of asserts certainly help. It would be better if you could get the node counts at say 1 ply and 2 ply for all the positions in a test suite. Then you could diff them with the known results and hunt down errors much faster. A bit of hacking to crafty and you could probably do this, but in the same time you could also probably debug your move generator too... It sounds like you are doing it the 'hard way', in that you are trying to calculate legal moves statically without using search to figure out anything. I do this in my program, and it is a fun thing to do, but it is definitely more difficult than letting search figure out if a move leaves you in check or not. If you are doing it statically, beware of the following scenario: BK a4, BP e4, WK h8, WR h4, WP d2 Now, if white plays d2-d4 your move generator might think it can play exd4 en passant because the pawn on e4 is not pinned! > >Yes. Test more frequently instead of writing the whole generator and _then_ >test. ;) > >Regards, > >Sargon
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