Author: Robert Hyatt
Date: 21:02:56 06/07/02
Go up one level in this thread
On June 06, 2002 at 20:57:14, Vincent Diepeveen wrote: >On June 06, 2002 at 20:35:03, Robert Hyatt wrote: > >I wrote 20 pages of explanation with examples what >is completely impossible to do in bitboards very >fast in my evaluation, about a year ago (bit less). >Then you said: "well i don't need that info for my >evaluation, so bitboards is ok for me". > >That's a choice you make. But please don't do as if you have >forgotten again those 20 pages. If you don't need a better >evaluation, but only a very elementary basic bean counter >evaluation, then that's your choice. > >My choice is doing more in evaluation, and i can't use >bitboards for that. > >Best regards, >Vincent Vincent, 5 years ago you explained why I couldn't do a "decent" mobility in Cray Blitz using vector hardware. I responded by showing you how I first computed the "worth" of each square on the board, and then with clever vector operations I _could_ sum up these square values to have something better than a simple "number of squares attacked" sort of mobility. There is _nothing_ bitboards can't do.. They are simply an alternative data structure approach that is computationally equivalent (in terms of capability) to _any_ chessboard representation around. Nothing more, nothing less. You should realize that because _you_ can't do it doesn't mean nobody else can either. And just because _you_ do do something does _not_ mean that something must be done by everyone or else their programs suck. My "approach" must be doing something right based on ICC results between our two programs... > >>On June 06, 2002 at 19:47:14, Vincent Diepeveen wrote: >> >>>On June 06, 2002 at 10:25:25, Robert Hyatt wrote: >>> >>>>On June 05, 2002 at 17:31:45, Gerd Isenberg wrote: >>>> >>>>>On June 05, 2002 at 13:22:30, Vincent Diepeveen wrote: >>>>> >>>>>>On June 05, 2002 at 04:14:41, Gerd Isenberg wrote: >>>>>> >>>>>>Gerd, a 33% speedup isn't much if you first slow down 2 times. >>>>>>Right now the crafty datastructure is exactly 2 times slower doing >>>>>>what i can do without bitboards. >>>>>> >>>>> >>>>>Vincent, if, as you claim, bitboarders are two times slower per se on 32bit >>>>>hardware, then i expect a speedup of >= 100% with bitboards on 64bit hardware. >>>>> >>>>>Gerd >>>> >>>> >>>>This argument goes in circles, because he also claims they are not very >>>>good on 64 bit machines either... >>> >>>Not really. the problem is the bitboarders have a different goal it seems. >>>If all you want is a Sum(squaresattacked) as mobility function, then sure >>>bitboards are an interesting thing to use at 64 bits processors. If you want >>>more, then bad luck with bitboards. Factor 2 slower. >> >>based on what? Your lack of experience with them or proof that there are >>some things that bitboards can't do? I know the latter is not true... >> >>Why do you want to waste so much time trying to explain why this approach >>is bad, when you have not tried it yourself. It takes time to get used to >>it. once you do, you discover that a lot of those "problems" are imaginary >>only. >> >> >> >>> >>>At 64 bits processors 33% faster, still like 1.6 times slower. >>> >>>Best regards, >>>Vincent >> >> >>Again, what single cpu machine at 1ghz can run crafty at 1.5 M nodes per >>second? Absolutely none unless we go to a Cray. Or a Mckinley 64 bit >>processor...
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