Author: Robert Hyatt
Date: 20:18:32 10/24/99
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On October 24, 1999 at 16:02:34, Frank Schneider wrote: >On October 24, 1999 at 10:08:45, Robert Hyatt wrote: > >>On October 24, 1999 at 05:59:40, Frank Schneider wrote: >> >>> >>>I haven't tried the 'strings lapetite.exe', but I believe you that there are >>>lots of strings that were just translated. I agree that is strong evidence >>>that lapetite's I/O is based on Crafty. But is there any evidence that the >>>engine is still a crafty clone? >>> >>>Copying an engine is, from my point of view, much worse than reusing the >>>I/O stuff and structure of the userinterface. >>> >> >>Run the second test I mentioned: start "La Petite" under a debugger, and >>look for the area where all the 64 bit masks are in memory. You will find >>patterns like 80000000 00000000, 40000000 00000000, 20000000 00000000, etc. >>then look for the rotated masks which are like the above, but in a different >>order (64 bits, 1 bit set). Then compare to crafty.exe. Look at data.c to >>find the pre-initialized scoring array patterns. See if you can find 'em in >>La Petite. :) >> >>etc. >I don't have La Petite. > >But I have very similar bit masks in Gromit (only 16 bit, because Gromit >does not use bitboards) and I wonder how to write a bitboard-base program >without such bit masks. Is there anything special about the order of masks >in Crafty that is unlikely to be invented independently by others? there are 64 of the masks that are just 1 bit shifted right slowly but surely. I can't imagine why you would have such masks (notice that they are each 64 bits long) if you aren't doing bitmaps. I have another set that has one bit set in each 64 bit value, but the bit isn't in the 'sliding' pattern, as it is used to update the rotated-left-90-degree board. Another set of 64 for each of the two 45-degree-rotated boards. Those are pretty unique to my style of rotating... There are many other masks as well, including the compact-attacks array of values that _nobody_ would likely have without using the crafty engine (this was the code done by Mark Bromley). > >Do other bit board based programs use such masks? How do they look in >Inmichess? Insomniac (if it uses bit boards)? any bitboard program probably has the 64 masks with the sliding 1, but the other 3 sets are very unlikely, and the compact-attack stuff is probably impossible to reproduce exactly without copying, as there are so many different ways to do the same thing. > >I agree that it is something different if LaPetite uses the same scoring arrays. >Everyone uses them, but finding lots of identical scores would be surprising. > > >I'd really like to see a statement here, where G. Mueller gives her point >of view. > > >Frank So would I. Because it is so blatant. But G. Mueller didn't discuss voyager a year ago when she burst upon the scene with a program stronger than almost any new amateur, complete with parallel search... I doubt we will hear anything now...
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