Author: Vincent Diepeveen
Date: 13:46:35 09/12/01
Go up one level in this thread
On September 12, 2001 at 09:55:11, Robert Hyatt wrote: >On September 12, 2001 at 09:49:09, Vincent Diepeveen wrote: > >>On September 12, 2001 at 00:19:33, Robert Hyatt wrote: >> >>>On September 11, 2001 at 22:46:43, Vincent Diepeveen wrote: >>> >>>>On September 11, 2001 at 12:32:27, Uri Blass wrote: >>>> >>>>>On September 11, 2001 at 10:43:01, Robert Hyatt wrote: >>>>> >>>>>>On September 11, 2001 at 10:27:40, Uri Blass wrote: >>>>>> >>>>>>>On September 11, 2001 at 10:19:31, Robert Hyatt wrote: >>>>>>> >>>>>>>>On September 11, 2001 at 08:51:20, K. Burcham wrote: >>>>>>>> >>>>>>>>> >>>>>>>>> >>>>>>>>> >>>>>>>>> >>>>>>>>>i understand your explanation for the Rg8 and the Rf5 moves bruce. >>>>>>>>>that deep blue might have seen a loss in both of those lines. >>>>>>>>> >>>>>>>>> >>>>>>>>>i only use the word blunder when during normal game mode or in >>>>>>>>> analysis mode the score will jump maybe 2 or more points, >>>>>>>>>when the next move is made. >>>>>>>>> >>>>>>>>>for example in this deep blue blunder SOS scores this position >>>>>>>>> black is down -1.65. at depth 15. you can see in the analysis that >>>>>>>>>the score imidiately jumps and climbs to +6.41 for white with 44. ...Rd1. >>>>>>>>> >>>>>>>>>in the case of the deep junior vs shredder, in the world championship >>>>>>>>> i have analyized the 5+ change in score. this was not a single >>>>>>>>> move blunder like defined above. in the deep junior game >>>>>>>>> shredder didnt have a clue of the deep pawn value and its ability >>>>>>>>> to stop them. then when it finally saw what was really going on >>>>>>>>>shredder started adjusting its eval very quickly, and the score jumped >>>>>>>>> 5+ points. >>>>>>>>> >>>>>>>>>and i am aware that you already knew all of this----i was just explaining >>>>>>>>> my logic for my applicaton of the word blunder. >>>>>>>> >>>>>>>>this just means that SOS doesn't understand the position yet. When I ran >>>>>>>>this, I got +3.5 or so. On Rd1 my score gets significantly worse. Which >>>>>>>>simply means that they probably searched the alternatives deeper than I did >>>>>>>>and found that they were bad also. >>>>>>> >>>>>>>I rememeber that they admitted that Rd1 was result of a bug. >>>>>>>Their score for Rd1(-1.80) does not make sense >>>>>>>in every reasonable depth >>>>>>> >>>>>>>They did not play Rd1 because they found >>>>>>>that the alternative is worse. >>>>>>> >>>>>>>Uri >>>>>> >>>>>> >>>>>>I don't believe -180 is the "score" I think it is an indication of a fail >>>>>>high. They didn't resolve a fail high unless a second fail-high occurred, >>>>>>since knowing that A is better than B is enough to play A. If you know >>>>>>that A and B are both better than C, then you have to re-search A and B to >>>>>>find out which is the better move. I believe their bug was in the code that >>>>>>handled this when a time-out occurred. >>>>> >>>>>-260 was the score for Rf5 based on their output and it means that the score >>>>>for Rd1 was more optimistic for black. >>>>> >>>>>It seems clear to me that the stupid mistake was result of a bug. >>>>> >>>>>I guess that the bug happens only after failing low and not being able to solve >>>>>the fail low or to finish the iteration on time. >>>>> >>>>>Uri >>>> >>>>In diep i only play a move that failed high after research is finished. >>>>if time gets out then i do not play the move failing high at this moment >>>>i play th ealternative which was searched better. >>>> >>>>Still many programs however to today would play the failed high move. >>>> >>>>As bob indicates this looks easy case to me without much discussions. >>> >>> >>>If you fail high, but can't resolve the fail high before running out of time, >>>I don't see any problem whatsoever with playing the fail-high move. However, >>>if you fail low, and resolve that, then fail high on two moves without resolving >>>either, then playing one of them is _very_ risky... >> >>It is very risky to play a move that fails high. I have all kind of >>stupid extensions like SE, some threats, checks. All is based upon alfa and >>beta values, so when i research a mainline diep sees tactical way deeper >>than when it gets the fail high. Hence the 2 searches are not based upon >>the same lines, in short that means that a fail high can't be reliable. >> >>Suppose next horror scenario: >> >> program searches very long onto a move becaus eof whatever reason >> (fail low or whatever delay with the opponent). Then suddenly you search >> real deeply. >> >>The opponent makes a non expected move. Program gets a fail high for >>a nonsense move, doesn't have time to resolve and plays that nonsense move. >> >>Please test some games you lost with crafty and try to figure out how many >>moves that failed high in the end didn't become a new PV, just the *risk* >>of it which was no problem in the past, is just too much to take in nowadays >>computerchess where every move must be from high quality. There is no space >>for worst cases to happen. That's why i don't play a move when it fails high, >>only after it has been researched. NO risks! > > >I have done this extensively. I've not found any cases where a "phony >fail-high" occurred, other than on the PVS searches (null-window). I don't >accept fail highs there without a valid research. But on the root alpha/beta >window, I do accept a fail high and have never found a case where it was wrong. >If I did, I would consider that a bug and fix it. For diep results were different. Note that we do things different in the root. I am always searching the first move with [-oo,oo] and the rest with alfa,alfa+1 in the root. Best regards, Vincent
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