Author: Chessfun
Date: 12:39:47 12/18/99
Go up one level in this thread
On December 18, 1999 at 13:10:24, Albert Silver wrote: >On December 18, 1999 at 11:25:34, Chessfun wrote: > >>On December 18, 1999 at 05:51:30, allan johnson wrote: >> >>>On December 17, 1999 at 17:10:12, Albert Silver wrote: >>> >>>>I seem to have run across a bizarre problem and wonder if this might not be a >>>>bug in Fritz (5 or 6) or one of the infamous null-move problems. I was analyzing >>>>the following position which was part of some analysis done on >>>>Yakovich-Stefanova, Sevilla op, 1999: >>>> >>>>r4rk1/p3bppp/nn6/1N6/Ppp1P3/1P2BP2/N3K1PP/R2R4 w - - 0 18 >>>> >>>>In this position the indicated move is 18.Nxa7! Fritz never finds this (at least >>>>up to 14 plies) and I decided to check the lines which follow: 18...cxb3 and >>>>here again, Fritz sees nothing for White and the eval drops with each ply; yet >>>>as soon as I feed it the next move 19.Bxb6 its eval shoots up in White's favour. >>>>What gives? >>>> >>>> Albert Silver >>> >>>Albert Rebel C on my Celeron 433 plays Nxa7 within 4 seconds with a score of >>>0.80.The score, however, goes down over the next few moves.(Nxa7 Rxa7 >>>Bxb6 Rb7 Bd4 c3 Rac1 Rc8 f4 Rd7 0.24) >> >>Fritz sees this line as + 1.0 depth 11/11. > >I am amazed. What version of Fritz? I ran this through Fritz 5/16bit, Fritz >5.32, and Fritz 6 and they all prefer 18.bxc4. They never choose 18.Nxa7 at >that depth. > I should have been clearer. After putting the moves as posted above in (Nxa7 Rxa7 Bxb6 Rb7 Bd4 c3 Rac1 Rc8 f4 Rd7 0.24) This line if forced in Fritz 5.32 sees as +1.0 depth 11/11. Thanks. > >>>CM6000 plays Nxa7 also but with an initial eval of 0.53.It,too,drops after >>>Nxa7 cxb3 BxB6 bxa2 Rxa2. >> >>This appears the critical line. >> >>>Is it supposed to be a win for white? Fritz 5.32 >> >>Win !! I think not... >> >>>doesn't consider Nxa7 but maybe the move, as Paul says, is not winning. >>>Cheers Allan >> >>Fritz: A bug?. This is a strong heading for this thread. Why not "look at this >>position". >> >>Anyway...clearly Nxa7 is not the best move. Further Fritz's eval after move 19. >>Bxb6 "shoot's up" hmmm that's not what I get after playing the next two moves, > >That is two moves later. I'm talking about after 19.Bxb6. The point is that if >it thinks the position here is at +1.22 after 8 plies, +0.94 after 9 plies, and >+1.09 after 10 plies then it should have said this prior to 18.Nxa7 after 11, >12, and 13 plies respectively, but it doesn't. > >>that it sees in the line. 19.....bxa2. 20. Rxa2 Bc5. where 21. a5...Rxa7 22. >>Bxa7...Bxa7 when Fritz sees Rd7 as +0.34. >> >>If you let Fritz at 18. Look at a couple of lines you will see it considers Nxa7 >>but sees this as inferior to bxc4 which I believe is the best move in this >>position. > >Possible but what is your line? > > Albert Silver > >> >>No engine I use will play Nxa7 at tounament time controls. I have looked at >>endless variations. >>Thanks.
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