Author: Robert Hyatt
Date: 14:51:26 12/10/03
Go up one level in this thread
On December 10, 2003 at 16:52:47, Matthew Hull wrote: >On December 10, 2003 at 15:27:14, Robert Hyatt wrote: > >>On December 10, 2003 at 10:25:20, Bob Durrett wrote: >> >>>On December 10, 2003 at 10:07:07, Robert Hyatt wrote: >>> >>>>On December 10, 2003 at 09:41:18, Bob Durrett wrote: >>>> >>>>>On December 09, 2003 at 23:22:12, Robert Hyatt wrote: >>>>> >>>>>>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. >>>>> >>>>>Another relevant thought: >>>>> >>>>>I have seen engines play a move [and display 0.00] which is obviously intended >>>>>to give the opponent an opportunity to repeat the position a third time. Upon >>>>>further extensive analysis, I have sometimes found that the engine's doing so >>>>>was a terrible mistake. Two types of "terrible mistakes" can occur: >>>>> >>>>>(a) the engine could have played a much stronger move but didn't, or >>>>>(b) the opponent engine does not repeat the position a third time but instead >>>>>plays a much stronger move which could have been prevented. >>>>> >>>>>In my view, engines which make these mistakes have "bugs" in them, or simple >>>>>programming errors. >>>>> >>>>>Bob D. >>>> >>>> >>>>Let's define the context precisely here. I have seen what you describe. But >>>>it is not a bug. Any more than an engine grabbing a pawn that later loses the >>>>game is a bug. The context is "the engine search space". If this search >>>>space says "repeating for a 3rd time to get a draw score is the best I can do" >>>>then that is the best the engine can do, within its search horizon and search >>>>space. That isn't a "bug". It is a "shortcoming" of insufficient depth or >>>>knowledge. As a human have you ever played a move that you later discovered >>>>was bad? Was that a "bug" in your neurons, or just a lack of search or >>>>understanding? >>> >>>Only a computer programmer can define the word "bug." : ) >>> >>>Bob D. >> >>Actually I believe Grace Hopper originally defined it. :) >> >>A moth in a relay. :) > >We had a possum get fried in an electrical power breaker box, taking down the >entire datacenter. Stank horribly, too. We see some of that with squirrels which appear to be pretty stupid. :) They like to bridge two power lines where they come in to a building, since the bare metal is exposed and is sometimes less than 24" apart.
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