Author: Uri Blass
Date: 13:25:42 04/29/03
Go up one level in this thread
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? 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. 2)About which engines do you talk? 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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