Author: Vincent Diepeveen
Date: 06:49:09 09/12/01
Go up one level in this thread
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!
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