Author: Uri Blass
Date: 09:41:34 07/26/01
Go up one level in this thread
On July 26, 2001 at 10:48:47, Robert Hyatt wrote: >On July 26, 2001 at 08:40:33, Uri Blass wrote: > >>On July 26, 2001 at 08:18:42, Robert Hyatt wrote: >> >>>On July 26, 2001 at 00:43:48, Bruce Moreland wrote: >>> >>>>On July 25, 2001 at 21:26:18, Robert Hyatt wrote: >>>> >>>>>On July 25, 2001 at 18:36:08, James T. Walker wrote: >>>>> >>>>>>This position arose today in a game between Hiarcs 7.32 vs Century 3.2. >>>>>>Although Hiarcs searched for 6 minutes on an Athlon 900 with 128M hash and it's >>>>>>score dropped from the previous 0.87 to -0.56 it still could not resist the BxN >>>>>>which I believe loses. I think almost any move which saves the Bishop keeps >>>>>>white alive. Best is probably Kxb4 or Be3. Crafty is very fast to avoid BxN. >>>>>>Junior7 is slow but finds it in a little over 1 minute. >>>>>> >>>>>>[D]8/p4k1p/6p1/8/1p2P1P1/1Kn3P1/3B3P/8 w >>>>> >>>>> >>>>>This is all about knowledge. White's bishop is the only hope to restrain the >>>>>black passed pawn and also help on the other side of the board. If it goes, >>>>>black's distant passer makes this a normally won ending for black. >>>>> >>>>>I can't imagine a program trading the last piece and giving the opponent a >>>>>distant passer, just on general principles, unless it sees some sort of tactical >>>>>trick to sneak in its own pawn even quicker... >>>>> >>>>>If a program wants to aspire to be a GM, it _must_ know something about such >>>>>endings... >>>> >>>>The reason a program would take the knight is that being up a pawn in a K+P >>>>ending is usually better than being up a pawn in a B vs N ending. >>>> >>>>I don't think a program "has" to know about this kind of stuff in order to be a >>>>GM, any more than a human has to be able to find a middlegame mate in 15 in 1/4 >>>>second, has to be able to demonstrate a winning Fine 70 line in 1/2 second, or >>>>has to be able to call mate in 95 in a KBN vs KN. >>>> >>>>Being a GM is not about being able to blend in perfectly with the GM community. >>>>It's about being able to generate results comparable to those attained by GM's. >>>>If the program is stupid in some circumstances, this is not necessarily fatal as >>>>long as the weakness can be masked. >>>> >>>>bruce >>> >>> >>>If a program doesn't know that being a pawn up, but with the opponent having >>>an outside passed pawn, is most likely lost, then it is not going to be able to >>>see that with search, >> >>Program can see it by search afer enough time. >>Even Hiarcs that is relatively slow could see it after some minutes on pIII800. >>Other programs are faster than hiarcs in seeing it but they do not see it at the >>root like Crafty and they may need 1 minute on PIII800. >> >> and it is going to get hit on over and over once the >>>opponent realizes it. >> >>The opponent needs to get into a pawn endgame and in most games the opponent >>cannot go into a pawn endgame. >> >> It happened to me with cptnbluebear many times. Once, >>>4 games in a row in fact, before Roman said "you _must_ fix this..." >> >>When the hardware gets better the program can see more by search and the program >>may avoid the pawn ending by search. >> >>> >>>I don't think you can mask a weakness that lets a program step into a totally >>>lost endgame position thinking it is doing a good thing. >> >>I believe that Deep search can help here. >>In the relevant example the program that I tried except Crafty do not know it by >>chess knowledge but they are not going to fall into the trap at tournament time >>control. >> >>Uri > > >That doesn't help. back up 4 plies in the game. The program might still like >this position because it thinks it can rip the knight and not lose any material. >But once it gets here, it searches deeply enough to realize (a) if I take the >knight, I don't lose material immediately but the passed pawn is going to win; >(b) if I don't take the knight, I lose material in another way. I am screwed >either way. But 4 plies ago I thought I could avoid the material loss by doing >(a) but I just didn't understand the resulting position. In the relevant example not trading is a good alternative and there is no problem of losing material. In theory there may be a position when the mistake was 4 plies before the trading but practically it does not happen often. I agree that it is better to solve things by evaluation but it does not mean that search does not help. Uri
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