Search found 16819 matches

by bob
Tue May 08, 2007 12:41 am
Forum: Computer Chess Club: Programming and Technical Discussions
Topic: Programmer bug hunt challenge
Replies: 32
Views: 28750

Re: Programmer bug hunt challenge

I think that the standard should redo e.p. so that the square is not named unless capture is possible. There is a potential difficulty with that, the clause "unless capture is possible" needs stricter definition. What if the en passant capture is a pseudo-legal move but not a genuinely legal move i...
by bob
Mon May 07, 2007 10:58 pm
Forum: Computer Chess Club: Programming and Technical Discussions
Topic: Programmer bug hunt challenge
Replies: 32
Views: 28750

Re: Programmer bug hunt challenge

And what about the situation where the pawn move revealed a check on the enemy king? Even if an opposing pawn could theoretically capture e.p., this would also not be legal. Would you omit the e.p. square in this case as well from the FEN notation? FEN says nothing about the legality of moves for t...
by bob
Mon May 07, 2007 5:28 pm
Forum: Computer Chess Club: Programming and Technical Discussions
Topic: Advice on stabalizing the eval needed
Replies: 11
Views: 11145

Re: Advice on stabalizing the eval needed

In RomiChess the piece/square tables are created dynamically before each search. This can lead to some extreamly unbalanced evals leading to things like bad sacrifices and other pathalogical behaviors. So, what is best, limiting each square to a maximum or adding up all the squares and scaling them...
by bob
Mon May 07, 2007 5:23 pm
Forum: Computer Chess Club: Programming and Technical Discussions
Topic: Interesting position from Jouni Uski
Replies: 27
Views: 22843

Re: Interesting position from Jouni Uski

Thanks Bob Yes indeed that was the explanation. I have to say I dont like that feature though, leads to confusion like this. Wouldn't it have been better to just print the the final PV at the end of the small depth searches, so what, it scrolls a few lines of text up the screen. Regards Geoff I don...
by bob
Mon May 07, 2007 5:21 pm
Forum: Computer Chess Club: Programming and Technical Discussions
Topic: Interesting position from Jouni Uski
Replies: 27
Views: 22843

Re: Interesting position from Jouni Uski

Zlaire wrote:So basically Crafty can't 'analyze' pretty much any mate in one problems on default settings?
Depends on what you mean by "analyze". You can always make "noise 0" the default. It just makes the program _very_ chatty, particularly in endgames.
by bob
Mon May 07, 2007 5:17 pm
Forum: Computer Chess Club: Programming and Technical Discussions
Topic: Mysterious segfault
Replies: 18
Views: 14996

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: 51506

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: 13203

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: 22843

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: 10974

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'...