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Endgame table base formats

Posted: Fri Apr 15, 2011 5:23 pm
by Eliyahu
Hello!

I'm in an AI class and one of our projects is to construct a chess AI. It's optional to use things like opening books and end game tables, but I am looking into how to use it. We're permitted to use existing books and databases.


Here is my understanding of opening books and end game databases:

Opening books contain a hash code representing a board position and a evaluation of that position. Then, as potential moves are generated, they can be checked against the values in the opening book in order to quickly and easily determine the best available action.

For endgame databases, we again have a hash code for a board position and instead of an evaluation, we have a value representing the number of moves required for a checkmate. So, after checking potential moves against this database, the chess engine will chose whichever action the number of remaining moves until checkmate.

Is my understanding about what these files contain correct?


Now...one hitch is that we aren't using Winboard, Xboard, Arena, etc. Just a command line client and server that a group of students made.

Because there's an explanation of the .bin file format for Polyglot opening books, I'll be able to use that type of book in my program.

But for the end game, most of the table bases I've found are either in .md5 or .tbs format. I am not sure how to read these files or what they contain. How can I make use of a existing table base without having to use one of the interfaces mentioned above?

Re: Endgame table base formats

Posted: Fri Apr 15, 2011 6:06 pm
by hyatt
.md5 is not a tablebase format. It is an md5 "checksum" that can be used to verify that a tablebase was correctly downloaded, by computing the md5 sum of the tablebase and then comparing it to what the number should be. .tbs is a "summary" file only that contains stats like longest distance to mate, shortest distance to mate, number of won, lost and drawn positions, etc...

what you want are the .emd files (which are the compressed tables)...