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Subject: Re: Shredder wins in Graz after controversy

Author: Robert Hyatt

Date: 20:22:12 12/09/03

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On December 09, 2003 at 19:36:05, Bob Durrett wrote:

>On December 09, 2003 at 13:21:35, Robert Hyatt wrote:
>
>>On December 09, 2003 at 13:02:56, Bob Durrett 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.
>>>>
>>>>how do you expect a GUI to make the right decision? imagine the following
>>>>absurdity: jonny is running without GUI and happily repeats moves against
>>>>shredder, and does not claim the draw because the engine doesn't know about it.
>>>>shredder has a bug and allows a 3-fold repetition but will deviate before the
>>>>fourth repetition. now shredders GUI stops shredder from moving, and says "i
>>>>claim a draw with my move XY because of 3fold repetition" - this would have been
>>>>hilarious for everybody except SMK :-)
>>>>
>>>>since 3fold repetition is something you claim or don't claim based on the
>>>>current position, it is clearly something the GUI shouldn't be doing!
>>>>
>>>>cheers
>>>>  martin
>>>
>>>THIS suggests the obvious changes which should be made to engines and GUIs ASAP
>>>by all chess programmers.
>>>
>>>Before an engine &/or GUI claims a draw, it should evaluate the position and
>>>determine whether or not it has a strong advantage.
>>
>>The engine already _does_ this.  It searches every root move individually
>>and chooses the one that produces the best score.  If you get a draw
>>score back, you can safely assume that no other move will give you a
>>"strong advantage" since the score of 0.00 was better than any other move.
>>
>>QED.  It chose the drawing move, thinking a draw was the best outcome
>>possible in this particular position.
>>
>>
>>> If it does have a strong
>>>advantage, then claiming a draw would be precluded by the programmer.  In other
>>>words, the software would be programmed in advance to make the sensible choice.
>>
>>Which it already does, as I explained.
>>
>>
>>>
>>>Similarly, the engine/GUI should be programmed to claim a draw by repetition in
>>>cases where repetition can be played and when also the engine evaluates the
>>>position as being a strong disadvantage.
>>>
>>
>>The engine will evaluate the position as 0.00 in the above case.
>>
>>
>>
>>>Obviously, humans avoid claiming repetition draws whenever they are winning and
>>>claim repetition draws whenever they can if they are losing otherwise.  In
>>>positions perceived to be equal, humans may or may not claim the draw by
>>>repetition depending on other factors such as tournament standing.
>>
>>If you play a move that repeats for the third time. You can claim the
>>draw.  Or your opponent can claim the draw immediately when it is his
>>move.  Playing a repetition for the 3rd time and wishing your opponent
>>would not notice reminds me of "Grumpy old men".  "You can wish in one
>>hand and crap in the other, and see which one fills up first."
>>
>>:)
>>
>>>
>>>Chess computers should be programmed similarly.
>>>
>>>Bob D.
>
>Bob Hyatt:  I don't mean to be unkind, but perhaps you should read my bulletin
>again.
>
>Bob D.

I also don't mean to be unkind, but must respond "why".  Do you think I
missed something or misunderstood something?

This nonsense about playing a 3-repeat move and hoping the opponent won't
see it is totally ridiculous in the context of alpha/beta searching that we
are all using.





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