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Subject: Re: Engine that prints out all variations in perft?

Author: Russell Reagan

Date: 09:54:46 03/27/04

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On March 27, 2004 at 11:54:27, Andrew Wagner wrote:

>Anybody have an engine that has modified perft to output all variations?
>Preferably to a text file or something...?

That would be etremely slow to write all of that to disk for anything but a very
quick perft. Crafty visits over 6 million variations per second on my machine
when calculating perft. Even if the moves are only 4 characters long, at 4 moves
per variation, that's close to 100 MB of data being generated per second.

I think a better solution is to keep track of more than just counting positions.
For instance, keep track of how many castling moves were made. Or better yet,
how many times white castled kingside, and queenside, and how many white
promotions to bishop, and so on. Then you can modify another program to keep
track of the same things, or some nice person here might add that to their
program and send you a copy. I think Tom Likens has this kind of information
when you run perft in his program, Djinn. If you ask nicely he might send you a
copy.

I like this way because it is relatively easy to determine where you have a bug.
If the move count for white castling kindside is incorrect, then you know
exactly where to look in your program. Look at where you generate white castling
kingside moves.



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