Author: Uri Blass
Date: 04:22:47 04/30/03
Go up one level in this thread
On April 30, 2003 at 05:51:37, Drexel,Michael wrote: >On April 29, 2003 at 18:12:38, Uri Blass wrote: > >>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 > >That is the point. I created a personality for Chessmaster which beats >Chessmaster SKR +37 =42 -21 and Grailmaster 7 +35 =40 -25 in 5 min blitz. >It is very strong in open middle game positions. I am surprised that it is strong against other chessmaster personalities. I do not understand it. Antisymmetric evaluation is to help you against other opponents and I do not expect it to help you in games against yourself. Uri
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