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Subject: Re: how to back up the PV with minimal work.

Author: Sune Fischer

Date: 02:33:31 01/21/04

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On January 21, 2004 at 03:56:39, Daniel Clausen wrote:

>On January 20, 2004 at 12:55:58, Sune Fischer wrote:
>
>[snip]
>
>>You are not adressing the other issues, the termination stuff and the added
>>code. It's not the copy-cost that mainly keeps me from doing it.
>
>Now you must be joking, Sune. I mean a PV is basically a list of moves. Surely
>someone who's capable of building a chess program is able to fill a list of
>moves and terminate the list somehow? Btw: I plan to use the STL-container
>'list' for this purpose. It's fast enough anyway and foolproof. (but then,
>terminating the list either with separate length-information or a NO_MOVE at the
>end of the list sound rather trivial too - to me :)

Well yes you can say that.
It's just that every time you manage to simplyfy something it's a small victory,
these are the things you strive for all the time.

I just checked one of the Crafty codes, there are five places calling SavePV.
In my case I would have need a few more, so that does begin to like clutter and
it does annoy me, sorry! :)

When I discovered I could extract the same line from the hash, in many cases
even a longer line, I saw _two_ good reasons for extracting it :)

>>>>The fundamental principle in chess programming is never to do any work
>>>>that is not needed.
>
>Well, that's arguable a fundamental principle for any programming task. While I
>can see that a programmer of an amateur engine can say that 'I couldn't care
>less about the PV', it strikes me a bit odd that a programmer of a commercial
>engine does the same. Afterall the initial message clearly showed that customers
>would like to rely more on the PV than they currently can (in case of Shredder)

If the users are serious about their demands they should buy another product.

>Next thing you guys say is "don't display the score anymore! the only thing that
>counts is the played move!" :) [yes, I'm joking now :)]
>
>
>>>>That's why I think it is a bit silly to update a PV a few hundred times (in
>>>>particular in qsearch) and then only print it out the last one.
>
>What I find a bit silly in this discussion is that both you and Bob seem to be a
>bit stubborn in this discussion. (excuse me! :)

Yeah, another one of those have agree to disagree I'm afraid.

> One likes to have a useful PV
>whenever possible, the other couldn't care less. No need (for both of you) to
>hide behind technical details to defend your respective point. :)
>
>Sargon (hopes both don't gang up on him now :)

I care about the PV, I just don't care infinitely much about it :)

Some day I may want to try an algorithm that makes it hard to get the PV, am I
going to let that stop me - no.

-S.



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