Author: Sune Fischer
Date: 10:17:15 09/21/02
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On September 21, 2002 at 12:20:24, scott farrell wrote: >I was just fiddling with my move ordering (as we all do from time to time). > >I found that my MVVLVA code worsened (is that a word?) my move ordering, and >slow my searches significantly. > >I altered it to just simply ordering the capture by the size of the material it >is to take, disregarding the size of the piece to perform the capture. > >As far as I know current wisdom for move ordering is something like this: >1. from hastable first >2. killers next >3. winning captures ordered by MVVLVA >4. other moves >5. losing captures > >My updated move ordering is: >1. from hastable first >2. killers next >3. all captures, ordered by the size of the captured piece (largest first), and >ties broken by size of attacker only >4. other moves >5. losing captures I disagree with conventional wisdom then, I hardly ever get a cutoff on the non-captures & non-killers, but maybe I have a bug or something. Here is a bit of statistics. Type of move / % of these moves in search / % cutoffs by these moves: hash.......: 0.44% 93.35% null.......: 27.91% 76.20% wcap.......: 3.39% 67.11% ecap.......: 0.45% 60.75% lcap.......: 3.87% 22.38% kill.......: 3.10% 22.34% ncap.......: 60.84% 0.50% (only the first column should sum to 1). As you can see even the losing captures produce relative more cutoffs than non-captures (excl. the killers), it is debatable if killers should go before losing captures by these stats, it's probably worth a try. I use two killers and sort captures by SEE, but I do suspect there is a bug (winning captures are not a lot better than equal captures?). I get only a 90% move ordering with this scheme, and I'm not counting nullmoves since those are not real moves, nor do I (obviously not) count transpositional or draw cuts, so I think I'm counting 'correctly'. -S.
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