Author: Robert Hyatt
Date: 20:22:12 12/09/03
Go up one level in this thread
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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