Author: Amir Ban
Date: 14:11:16 04/29/03
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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. >Note that being too optimistic is not always a result of overevaluating a >positional score and it may be a result of not understanding the positional >advantage of the opponent. > If I understand correctly you distinguish between counting a non-existent advantage and discounting a real disadvantage. This is interesting, but I don't make the distinction and don't believe that it matters much in the effect. >2)About which engines do you talk? > I won't be specific but it exists at the highest levels, and I'm familiar with it in many versions of my own. This is of course not a general problem of an engine but of its behavior in some types of positions. Amir >There are a lot of amateurs and today there are more than an hundred of free >chess programs. > >I guess that you did not think about the weak engines that part of them even >have no more than piece square table evaluation but it is better to make clear >if you mean only to the commercial programs or also to the top amateurs and the >program that are slightly weaker than them >(Ruffian,List,Sos,Yace,Crafty,Comet,Pepito,Aristarch...). > >Uri
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