Author: Uri Blass
Date: 02:19:54 09/11/01
Go up one level in this thread
On September 11, 2001 at 03:05:20, Bruce Moreland wrote: >On September 10, 2001 at 22:30:30, K. Burcham wrote: > >> [D] 4r3/8/2p2PPk/1p1r4/pP2p1R1/P1B5/2P2K2/8 b - - >> >> >>after the above position deep blue blundered with 44. ...Rd1. >>there was an immediate jump of 4 points with this move. >>not sure if this was a move mistake, slip, not sure. >>but with 44. ...g8 or 44. ...f5+ black is still 2.5 down >> with a losing position. i played this out with tiger 14 >> and ended with this position. mate in 9 with the f and g pawns. > >It is "blunders" that might provide us with insight. > >If a computer gives a knight in a manner that can be seen in a 2-ply search, it >should indicate that moves that appeared better also lost a knight, or perhaps >more. > >So it's possible that these other moves (Rg8, Rf5+) are refuted pretty deeply. >I have a hard time believing that DB just threw away material for no reason. > >bruce I remember from previous posts that it was a known bug of Deeper blue. I guess that the bug was a result of the fact that Deeper blue failed low. It saw that Rf5+ is bad but based on the logfiles it was not so bad to play an obviously losing move and I guess that for some reason after failing low it did a very short search to find another move because of the bug. I did not understand what was exactly the bug but I am sure that there was an agreement here that it was a bug. Here is Deep blue's logfile for the position It saw that the score for Rf5 is 2.6 pawns against itself and for some reason Rd1 was searched for a very short depth so it saw only 1.8 pawns against itself. hash guess pf5f6,Guessing f6 9(4) #[Rf5](-179)[Rf5](-179) -30v T=0 Rd5f5 kf2e2 Re8g8 pg6g7 Kh6h5 rg4g1 Rf5f3 bc3b2 Kh5h6 rg1g4 Rf3f5 bb2d4 Rf5f3 pc2c3 Rf3f5 9(6) #[Rf5](-163)######################## -163 T=12 Rd5f5 kf2e2 Re8g8 pg6g7 Kh6h5 rg4g1 Rf5f3 bc3b2 Kh5h6 rg1g4 Rf3f5 bb2d4 Pe4e3 bd4e3P 10(6) #[Rf5](-180)######################## -180 T=36 Rd5f5 kf2e2 Re8g8 pg6g7 Kh6h5 rg4g1 Rf5f3 bc3b2 Kh5h6 rg1g4 Rf3f5 bb2d4 Rf5f3 pc2c3 Rf3f5 11(6)<ch> 'f6' #[Rf5](-210)[Rf5](-210) -210v T=73 Rd5f5 kf2e2 Re8g8 pg6g7 Kh6h5 rg4g1 Rf5f3 bc3b2 Kh5h6 rg1g4 Rf3f5 bb2d4 Pe4e3 ke2e3P Rf5f1 ke3e4 Rf1f6p 11(6) #[Rf5](-260)v[find a move]#########[TIMEOUT][et3 1295 sec]#[Rg8](-183)[Rd1](-180) -180 T=204 Rd5d1 pf6f7 Rd1f1 kf2f1R Kh6h5 pf7e8R/q Kh5g4r --------------------------------------- --> 44. .. Rd1 Uri
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