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Subject: EGTB questions to Martin Fierz

Author: Alvaro Jose Povoa Cardoso

Date: 14:10:57 04/11/02


>hi alvaro,
>
>have you written your own program by now or did you adapt mine? if you are doing
>the second, then the answer to your question is "it's irrelevant" - and probably
>the answer is the same if you wrote your own program... my generator took 5
>weeks on a XP1600+ with 1GB ram to build the 4-4 database (and anything
>smaller). once you have this, you will never need to compute it again... another
>point is that in spanish checkers, you should be much faster building the db,
>because AFAIK kings sweep, and you have lots more captures which take you in
>smaller databases much faster than in english checkers, i.e. the number of
>passes per db you have to do should be much smaller.
>
>in the meantime, i have compressed my database, and am working on the access
>code. believe me: this is the part you have to do right - not the db computation
>itself.
>
>aloha
>  martin

Hi Martin,
nice to hear from you :)

Unfortunately I didn't even started. I'm anxious to read the code you sent me. I
have very litle time, since I work all day and get home very tired. But I'm very
interested in solving this EGTB problem. My interest in 32bit reversing is
because it will be used in the program search engine for 'white to move'
positions. I agree it is not a great issue but if I can do it a little faster
then I'll do it. Yes you are right about Spanish/Portuguese checkers greater
number of captures.

Martin, I red Jonathan Schaeffer's paper and I have doubts about resolving the
non-capture positions (I think I didn't understood all of the algorithm). My
(surely stupid) question is: When generating the tablebases we do have to make
an alphabeta search for these non-capture positions don't we? (contrary to the
capture positions in that we get the results from lesser piece databases).

Also, in the engine I was planning to put all the 4 piece databases in memory
and the others I read from disk. Do you think it is sensible?

Also, do you use 2 bits per entry in your databases or do you use a byte with
distance to win/loss?


Best regards,
Alvaro Cardoso



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