Author: Drexel,Michael
Date: 05:15:01 04/30/03
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On April 30, 2003 at 07:22:47, Uri Blass wrote: >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 It was only slightly antisymmetric. I had increased the parameter for mobility and reduced the parameter for Center Control drastically. Therefore the program played a very antimaterialistic agressive style and this seems to help against various Chessmaster personalities. Shredder 7.04 and Fritz 8.0.0.8 however got almost always favourably endgames and won. Michael
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