Author: Uri Blass
Date: 15:12:38 04/29/03
Go up one level in this thread
On April 29, 2003 at 17:11:16, Amir Ban wrote: >On April 29, 2003 at 16:25:42, Uri Blass wrote: > >>On April 29, 2003 at 15:17:32, Amir Ban wrote: >> >>>On April 28, 2003 at 11:30:08, Charles Worthington wrote: >>> >>>>That's an interesting question but I have one of my own. Is not the engine's >>>>choice of continuations based soley on its eval of the line? Many times I have >>>>seen Shredder follow its over optimistic evals to a dead draw as white. I would >>>>rather my program know where it really stands and whether or not it has >>>>realistic winning chances. Also...I personally would like to know where it >>>>stands as well. There is nothing quite so frustrating as to have an over >>>>optimistic eval turn on you and bite you. I have seen numerous situations where >>>>The King has an eval of +2 against Deep Fritz's -1 and it RARELY works out in >>>>The Kings favor. It's hard for me to muster faith in an engine that is clueless >>>>about it's own position and it is the one thing that keeps me from giving >>>>Shredder a fair shot at becoming my main engine. Enough times of seeing Fritz >>>>pull the rug out from under my Shredder eval has spooked me I guess. I just do >>>>not see how it is possible to handle a position properly when you cannot even >>>>eval it properly and in fast blitz time controls (3+2), I might also add that >>>>the "optimistic" engines almost always perform more poorly than the well >>>>balanced engines. The truth seems to perform better than the lie in this case. >>>>Of course this discussion is about self-inflicted optimism by tampering with the >>>>parameters so it seems even more extreme. You are taking an already-optimistic >>>>engine and furthering it's optimism. It would likely take many thousands of >>>>games to come to a conclusion as to which works best. Honestly though, I think >>>>that in this case having your program lie to you (and itself) will not prove >>>>beneficial. The program will play better if it has a full understanding of its >>>>actual chances and not imagined ones...Optimism causes the program to >>>>overestimate it's chances and play far too aggressively (ie. unwarranted >>>>sacrifices) in certain positions where caution is warranted. Against a human >>>>this may prove beneficial but against a program firmly grounded in reality it >>>>may prove fatal. So, like in life, I think the truth has to be better than the >>>>lie. And I think that extensive testing of these settings would show that, more >>>>often than not, the lie would come back to bite you. >>>> >>> >>>I agree. >>> >>>I believe overvaluation is the most common reason for engine losses. It's much >>>more common than undervaluation, a less fatal problem. This is especially true >>>in tactical situations, where the program with overvaluation seems not to see >>>tactics, because its search is meaningless. >>> >>>Amir >> >>1)What is overevaluation >>Do you mean positional score that is too high or only being too optimistic? >> > >I don't really see the difference. I prefer the term "overvaluation" over >"optimistic" (or maybe "bluffing") because the latter creates the illusion that >the program knows what's right and consiciously distorts it. All the discussion started from that idea to consiciously distort the true. The point is that if your program has a relative advantage against other opponents in the middle game and not in the endgame then it is better for it not to trade pieces if it does not have to do it. The idea was in that case to evaluate your pieces as slightly better than the opponent pieces with the exception of inferior positions. It is possible to do part of it by changing parameters in chessmaster and the problem is that it is not possible to tell chessmaster about the exception by only changing parameters. Uri
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