Author: Robert Hyatt
Date: 08:55:11 12/09/03
Go up one level in this thread
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. This is a zero-sum game. If I avoid a draw, I am doing so because I think I can win. Therefore my opponent will be trying to draw to avoid the same loss. It doesn't matter what my _real_ opponent will choose to do, what matters is what I _think_ he will do inside my search, because my search is given the task of playing a move that repeats for the 2nd or 3rd time (with a score of 0.00) or playing a move that avoids the repetition and doesn't give my opponent the opportunity to repeat. When you repeat for the third time, you definitely hand a draw to your opponent. He can take it or decline, beyond your control. But you have put the future of the game in his hands.. I don't repeat hoping my opponent won't. > >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 :-) The GUI doesn't make _any_ decision. It plays the move the engine supplies. If that leads to a 3-fold repetition, the GUI claims it correctly... I don't understand this "how do you expect the GUI to make the right decision?" stuff when the GUI only does what the engine tells it to do. If the engine says "play this move" then the GUI plays that move, and if that produces a 3-fold (or 50-move-rule) draw, then the GUI claims it, _knowing_ that the engine knew that was happening... > >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! It doesn't. The engine makes the choice to repeat. But once it does, it _knows_ it wants the draw, else the engine would have avoided it. You are saying the engine plays a move leading to a forced draw, but it isn't sure it wants to claim it. That is simply wrong. The search doesn't work that way... > >cheers > martin
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