Author: Stuart Cracraft
Date: 18:20:42 12/28/05
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On December 28, 2005 at 16:25:08, Roman Hartmann wrote: >On December 28, 2005 at 16:04:28, Tord Romstad wrote: > >>On December 28, 2005 at 15:31:55, Roman Hartmann wrote: >> >>>On December 28, 2005 at 15:27:34, Dann Corbit wrote: >>> >>>>How are you calculating mobility? >>>>A 10:1 loss in speed is very traumatic. >>>>Unless you are only counting wood in your evaluation, you should not see that >>>>traumatic of a degradation. >>> >>>Several problems: >>>-outdated board design 10x12 >> >>16x12 may be slightly more convenient, but 10x12 isn't outdated >>at all. There is no reason why mobility evaluation should be expensive >>on a 10x12 board. > >I only learnt recently about the 0x88 move generation sheme on Bruce Morelands >nice site. I guess I mainly wrote that in order to talk myself into rewriting >the movegenerator. > >>>-legal move generator instead of pseudo legal >> >>You shouldn't generate moves at all when evaluating mobility. This >>is almost certainly the main reason why you see such a big slowdown. >>When you generate moves, you do a lot of work which is not necessary >>when you just want to evaluate mobility. You don't need the moves >>at all, just the number of moves. > >If the mobility thing pays out, I will definitely take care of that problem by >adding a second move generator that only counts the moves but doesn't store >them. > >>Perhaps you can even omit some >>piece types. I don't evaluate pawn or king mobility at all (in my >>experience, there are better ways to evaluate king activity), and I >>have never seen any measurable difference in strength when I >>switch queen mobility on or off. > >Thanks for that info. >So far the version with mobility scores 228/300 in WAC (5s per move) while the >non-mobility version scores 254/300. But that doesn't tell much about the >positional play, of course. And probably I also didn't found the right weighting >for the mobility-factor yet. > >Roman > Mine is about 262/300 on WAC at 5 seconds per move with no mobility and about within 1% of that on the downside for mobility. That is close enough for me to take mobility especially considering that my mobility counter is still storing the moves unnecessarily. Once that is gone, the speed will be much higher with a better result. Stuart >>Tord
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