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Subject: Re: Effect of tablebases on programs' performance

Author: Jon Dart

Date: 20:20:20 05/27/01

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On May 27, 2001 at 21:42:39, James Swafford wrote:

>On May 27, 2001 at 20:26:47, Bruce Moreland wrote:
>
>>
>>Sometimes the increase is zero.  For instance, in my CCT3 games over the past
>>two days, none of them were affected by endgame databases.
>
>I used them in Tristram 5.0, which came out of retirement for CCT3.
>Tablebases became a factor twice.  The first time was while playing
>Arasan.  Towards the endgame (with seven pieces on the board),
>Tristram started probing wildly.  It probed the disks so much my
>nps went from 300k or so to < 30k.  I think it *costs* me half a
>point.  I can't be sure... but I went from a won position to a
>drawn one.

That's possible. I haven't analyzed that game yet. But at least you
were getting some benefit from the TBs (and remember, a TB hit is
giving you exact knowledge that can substitute for a *lot* of search).
Arasan had only 4-man TBs and wasn't helped at all by them at the
crucial parts of the game.

>I think it is interesting that so many people use the Nalimov stuff without any
>concern that at some point while the program is playing, it is not their program
>>actually playing

I don't think I'm bothered by that. As noted, TB use is pretty universal.
I got tired of playing other programs that have TBs when I don't.
Theoretical endgame knowledge is sometimes useful but a lot of times
it's unhelpful or even hurts you. The TBs keep you from being blind at
these times. And I don't feel the need to write my own TB decompression
code, no more than I feel the need to rewrite gzip or winzip.

Releasing a program with TB support is a different issue. As discussed at
one point during the tournament, it raises some licensing issues, especially
with those programs that are under GPL. If I were really adamant about
being under GPL I could see that as a reason to reimplement the TB support
code. As it is I'm not using GPL, but even so, I may keep the TB support in
the source but not distribute with TB support compiled in.

--Jon



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