Author: Robert Hyatt
Date: 06:55:11 09/12/01
Go up one level in this thread
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.
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