Search found 16793 matches

by bob
Tue May 08, 2007 5:50 pm
Forum: Computer Chess Club: Programming and Technical Discussions
Topic: Mysterious segfault
Replies: 18
Views: 14781

Re: Mysterious segfault

Indeed, I don't think Bob is right. He is right about that hardware allows you to do obtain double-length products and use double-length dividends, but the C standard forbids the compiler to make use of this hardware feature. int32*int32 should give you int32 with the high-order 32-bits clipped. If...
by bob
Tue May 08, 2007 5:42 pm
Forum: Computer Chess Club: Programming and Technical Discussions
Topic: Programmer bug hunt challenge
Replies: 32
Views: 28387

Re: Programmer bug hunt challenge

Why should they have different FEN strings? Because it is easier and hurts no one. There exists no ambiguity: it is always fully clear from a FEN if ep capture is possible or not. Writing the 50-move counter and the castling status is trivial, as they are supplied in the definition of the position....
by bob
Tue May 08, 2007 4:37 pm
Forum: Computer Chess Club: Programming and Technical Discussions
Topic: Interesting position from Jouni Uski
Replies: 27
Views: 22609

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
Tue May 08, 2007 4:35 pm
Forum: Computer Chess Club: Programming and Technical Discussions
Topic: Programmer bug hunt challenge
Replies: 32
Views: 28387

Re: Programmer bug hunt challenge

It seems to me that requiring the e.p. field in a FEN to be only present if there actually is a legal e.p. capture just puts a completely needless burden on the routine that converts board positions to FENs. No information is lost by putting a superfluous e.p. square. A possible reader for which th...
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: 28387

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: 28387

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: 10969

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: 22609

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: 22609

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: 14781

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 ...