Author: Robert Hyatt
Date: 09:32:15 12/09/03
Go up one level in this thread
On December 09, 2003 at 12:26:51, martin fierz wrote: >On December 09, 2003 at 11:55:11, Robert Hyatt 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. >> >>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. > >of course it is a zero-sum game. but that is not the point. your opponent may or >may not think that it is good to continue the game, even if it loses. why not >try? *every* human does this in 3fold repetition positions where he cannot lose. >you claim a draw because your opponent slipped up and allowed it. In this context, it simply doesn't make sense. The engine will repeat for the first time. If the opponent wants a draw, he will repeat also. The engine can _still_ avoid the second repeat (Crafty does this internally all the time since the engine specifically understands 3-fold at the root is a draw, but two-fold is not, while two-fold in the search is the same as a draw.) If My engine repeats the third time, it _wants_ the draw. Otherwise it would never have played the drawing move. > >>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... >you're missing the point. if i as a human can repeat a position and any >deviation from the repetition will benefit me, then i don't claim the draw. >leave that to your opponent to do if he so wishes. he can always still make a >mistake. >of course your engine knows it's a draw and it can't do anything better. but you >don't know whether your opponent knows, let him show that he knows. I don't see how this matters since the engine doesn't understand the concept of "my opponent might make a mistake." And, in fact, when the engine made the 2nd repetition, it could have deviated after that if there was a way to improve, so it didn't have to wait for the 3rd repeat to do so. By then it is too late. > >>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... > >no, you are simply wrong here :-) >there are so many positions where both sides are forced to repeat, because they >lose if they don't. e.g. i sac something, get a perpetual and if you go on the >wrong square with your king i win. if i make a quite move you defend against the >perpetual and win. this is a very common situation. i will definitely not claim >the 3fold repetition in such a position, because you just *might* go on the >wrong square. i can't do anything about it, the game is a draw. but since you >can still go wrong i won't claim the draw just yet, i have no reason to. i can >always claim it later. This does not happen in computer vs computer games. They resolve this at the _second_ repetition, they don't have to wait for the third and then play through it to fix the problem. >this reasoning is made by humans all the time. most chess engines can't do this >kind of reasoning. but that doesn't mean they aren't allowed to do it! Humans only do it because they didn't do it on the second repetition when it should have been done. Fortunately, computers pay a bit more attention to the game than that. :) > >cheers > martin
This page took 0 seconds to execute
Last modified: Thu, 15 Apr 21 08:11:13 -0700
Current Computer Chess Club Forums at Talkchess. This site by Sean Mintz.