Search found 16764 matches

by bob
Mon May 07, 2007 5:17 pm
Forum: Computer Chess Club: Programming and Technical Discussions
Topic: Mysterious segfault
Replies: 18
Views: 14455

Re: Mysterious segfault

actually if you multiply two 32 bit ints, you get a 64 bit result. Always has been this way. But if you don't follow that with a divide, which also has a 64 bit dividend, then you lose the extra bits. This has been a hardware feature to prevent problems with things like a = b * c / d; if it was all ...
by bob
Sun May 06, 2007 1:34 am
Forum: Computer Chess Club: General Topics
Topic: New engine from Russia
Replies: 74
Views: 50684

Re: New engine from Russia

also note that fixed-depth matches are not very useful. Not everyone has the same "ply" concept. Programs that do reductions lose a lot of ground when using fixed (equal) depth when compared to a program that doesn't. The reduction program might be moving at 1 second/move while the non-reduction pro...
by bob
Sat May 05, 2007 5:05 pm
Forum: Computer Chess Club: Programming and Technical Discussions
Topic: Forty five years ago
Replies: 19
Views: 12716

Re: More on the IBM 7090

The machine Kotov used for development was an IBM 7090, first released in 1960. It was the transistorized revision of the earlier and quite popular IBM 709, a vacuum tube machine. Computer time on a 7090 was available at the rate of about US$100 per hour. A picture: http://www.cozx.com/~dpitts/pix/...
by bob
Sat May 05, 2007 4:59 pm
Forum: Computer Chess Club: Programming and Technical Discussions
Topic: Interesting position from Jouni Uski
Replies: 27
Views: 22256

Re: Interesting position from Jouni Uski

Hi Bob I am intrigued now, lets have another peek at what is going on with Crafty on my setup. (Single CPU P4, WinXp, Chess Arena 1.1) I know the later Chess Arena betas, have fen bugs, but as far as I am aware 1.1 is OK. I forget which version of Crafty I originally tried so I downloaded it again....
by bob
Sat May 05, 2007 12:10 am
Forum: Computer Chess Club: Programming and Technical Discussions
Topic: Why is Core 2 Duo prefered for chess programming?
Replies: 11
Views: 10521

Re: Why is Core 2 Duo prefered for chess programming?

A single core-2 processor (just one CPU) is more than twice as fast as a single PIV 2.8ghz xeon. My office machine using both cpus hits 1.5-2.0M nps. My 2.0ghz core-2 laptop hits 5-6M nps. the comparison is startling... Note that the xeon box in my office is 32 bit, while my core-2 is 64 bit and I'...
by bob
Fri May 04, 2007 8:22 pm
Forum: Computer Chess Club: Programming and Technical Discussions
Topic: Programmer bug hunt challenge
Replies: 32
Views: 27878

Re: Programmer bug hunt challenge

Well, as the e.p. square here is only used to decide if the following move is legal, and not for determining if positions are different for hashing or applying the 3-rep rule, it is not a bug to consider that e.p. rights exist when no Pawn is present to enjoy these rights... Yes, precisely. Note it...
by bob
Fri May 04, 2007 8:20 pm
Forum: Computer Chess Club: Programming and Technical Discussions
Topic: Programmer bug hunt challenge
Replies: 32
Views: 27878

Re: Programmer bug hunt challenge

Well, as the e.p. square here is only used to decide if the following move is legal, and not for determining if positions are different for hashing or applying the 3-rep rule, it is not a bug to consider that e.p. rights exist when no Pawn is present to enjoy these rights... It's maybe not a "bug",...
by bob
Fri May 04, 2007 8:19 pm
Forum: Computer Chess Club: Programming and Technical Discussions
Topic: Programmer bug hunt challenge
Replies: 32
Views: 27878

Re: Programmer bug hunt challenge

I do not understand the bug There was no enpassent capture possible in the end of the first game so I do not see how clearing enpassent square between games could be relevant. There was no black pawn at b4 in the final position of the game. Uri some programs incorrectly (IMHO) set an EP target when...
by bob
Fri May 04, 2007 8:17 pm
Forum: Computer Chess Club: Programming and Technical Discussions
Topic: Interesting position from Jouni Uski
Replies: 27
Views: 22256

Re: Interesting position from Jouni Uski

I have tried again with the same commands posted above and obtained the same result you posted (i.e. correct mate found)... who knows what I did when I tried that for the first time! :shock: OK. To the best of my knowledge I haven't had an EP bug in many years. Except for the cases where a GUI fail...
by bob
Fri May 04, 2007 8:15 pm
Forum: Computer Chess Club: Programming and Technical Discussions
Topic: KQKB and KQKN heuristic for bitbases?!
Replies: 2
Views: 3265

Re: KQKB and KQKN heuristic for bitbases?!

For those kinds of endings, I don't think you even need 'em. KQKR is more difficult than either of those, and a simple "drive the king to the edge/corner and keep the kings close together is more than enough to force the win with kqkr. With kqkb or kqkn it is even easier...