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Subject: Re: Shredder wins in Graz after controversy

Author: martin fierz

Date: 11:00:08 12/09/03

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On December 09, 2003 at 11:29:58, Sune Fischer wrote:

>On December 09, 2003 at 11:13:56, martin fierz wrote:
>
>>On December 09, 2003 at 10:50:23, Sune Fischer wrote:
>>
>>[snip]
>>
>>>If the bare engine had been playing he would have had to add a few things the
>>>GUI normally takes care of.
>>>For UCI engines it is expected that the GUI handles certain (trivial) things.
>>
>>claiming a draw on 3-fold repetition is *not* a trivial thing. there are
>>different possible cases:
>>
>>1) if your opponent avoids it, he loses
>>2) if your opponent avoids it, he wins
>>
>>in case 2) you should of course claim the draw, because perhaps he will notice
>>he could avoid it. in case 1) however, you can safely repeat the moves, and not
>>claim the draw. it is *not* mandatory to claim a draw on the 3rd repetition. so
>>you should basically not claim it if you might win if your opponent avoids the
>>draw.
>
>Are you suggesting the UCI protocol should be forbidden? :)

not at all. if your engine claims a draw in a position where it might still win,
that is your problem. i'm saying that you can gain something by not
automatically claiming a draw whenever you can. as i said, if every UCI GUI
really claims a draw on 3fold repetition, then why didn't the shredder GUI claim
a draw by repetition after it occurred?? as you can see, it gained something by
not doing it :-)


>So you're saying if we take an engine and subject it to something it wasn't
>designed for it wouldn't work right?
>Doh!
nope. i don't know what jonny was designed for. i don't know whether the
programmer even made a conscious design decision that he wouldn't put in the
knowledge that a 3fold rep is a draw, because he knew the GUI would handle it.
he might just not yet have added that kind of code. jonny is quite a knew
program AFAIK, so perhaps he just hasn't got that stuff yet.

>Not really.
>The engine always plays the best moves it can find, if that is a repetition then
>it's a repetition. No point in continuing because the engines sees the draw and
>wants it.

not at all. the evaluation of a position where you have a draw in hand should
not be 0.00 but ">=0.00". that's how we humans think about such positions. the
programs are just too stupid to understand that :-)
you can and should have your opponent show you that he knows that it's a draw,
if you have a safe draw. for humans this concept is obvious. i can't help it
that it's not obvious to an alpha-beta tree searching program!

cheers
  amrtin



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