Author: Robert Hyatt
Date: 19:51:48 09/12/01
Go up one level in this thread
On September 12, 2001 at 16:46:35, Vincent Diepeveen wrote: >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 Ok.. that is why I search like I do. With an aspiration window. If I fail high on alpha,alpha+1, I _always_ research and don't accept the fail high unless it fails high on alpha,beta re-search as well. However, if it fails high there, I bump beta to +infinity and research again, and I don't have to get a score here to play the fail high move.
This page took 0 seconds to execute
Last modified: Thu, 15 Apr 21 08:11:13 -0700
Current Computer Chess Club Forums at Talkchess. This site by Sean Mintz.