Author: Bruce Moreland
Date: 00:25:46 12/30/00
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On December 29, 2000 at 06:52:51, Steve Maughan wrote: >Currently in my program I generate all of the moves then loop through looking >for the hash move, giving it a 'high' move order score went found. This works >well and is simple to implement. It would be (much) better to not generate all >of the other maoves and simply take the hash move and play it first, generating >all the other moves if a cutoff is not forthcoming. > >This give rise to a problem - how can I be sure that the hash move is legal? > >It could be the case that I have a hash collision - yes I use a 64 bit key but >it's still possible - and no doubt it would happen in the final round of the >World Championships just as I was about to slaughter Shredder 8 (;-)) yes in my >dreams I know!!). > >I guess I have a series of options: > >1) Ignore the possibility and realise that I'll never get to the last round of >the WMCCC. >2) Perform a full legal move check (expensive!) >3) Check that the piece to move is on the expected square >4) Do (3) and check that the destination square is reasonable for the piece to >move but don't bother about checking for sliding peices being blocked. > >At the moment I'm favouring (4) as this could be accomplished with a simple >lookup table. > >What do others do? Any advice appreciated! > >Regards, > >Steve Maughan > >PS I use a x88 structure. Mine uses a move table, so I just store a pointer to the move table element for the best move in the hash table. When I generate moves I will notice if that move is generated, and I will search it first. bruce
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