Author: Amir Ban
Date: 22:55:11 01/02/98
Go up one level in this thread
On January 02, 1998 at 17:39:22, Robert Hyatt wrote: >On January 02, 1998 at 16:50:29, Amir Ban wrote: > >> >>The first game Comet - Junior in CSCC has a challenging position for >>computers, fit for some test-suite material. >> >>On the 43rd move, black is an exchange up, and can win another piece to >>be a rook up, but this loses. >> >>Black manages to avoid Rxd3 on the 45th move, but plays it on the 47th >>move. Which program manages not to play Rxd3 both times ? Is there a way >>to win here ? It's not even clear to me that black can avoid losing. >>White can play 45. b6 or maybe even h3 and black is in some trouble. >>Also interesting is that white can save the piece by 45. c7 but that may >>be the only way to lose :) >> >>How to evaluate black's 43... e4 ? Maybe one exclamation mark for >>playing it, two exclamation marks for NOT playing it ? >> >>Strangely enough, white got a decisive advantage but then failed to win. >> >>Amir >> >> >> > > >I ran this and at move 45 crafty never considers Rxd3. But it does >believe that Qc5 gives black a significant advantage (almost +2). First >I'll give it's analysis when it is only allowed to consider Rxd3, then >I'll give complete analysis: > >(these are run on my notebook with a .75mb hash, so this can >be searched *far* quicker with bigger hash and a P6200 or >something...) > depth time score variation (1) > 7 0.25 -2.87 Rxd3 Rxd3 Qxd3 Qxd3 Rxd3 b6 Rd1+ Kg2 > Rd2+ Kh3 Rd8 Kg4 > 7-> 0.27 -2.87 Rxd3 Rxd3 Qxd3 Qxd3 Rxd3 b6 Rd1+ Kg2 > Rd2+ Kh3 Rd8 Kg4 > 8 1.08 -- Rxd3 > 8 1.16 -3.03 Rxd3 Qxd3 Qxd3 Rxd3 Rxd3 b6 Kg7 b7 > Rd1+ Kg2 Rd2+ Kh3 Rd8 > 8-> 1.18 -3.03 Rxd3 Qxd3 Qxd3 Rxd3 Rxd3 b6 Kg7 b7 > Rd1+ Kg2 Rd2+ Kh3 Rd8 > 9 1.59 -3.16 Rxd3 Qxd3 Qxd3 Rxd3 Rxd3 b6 Rd1+ Kg2 > Rd2+ Kh3 Rd5 b7 Rh5+ Kg4 Rb5 > 9-> 1.61 -3.16 Rxd3 Qxd3 Qxd3 Rxd3 Rxd3 b6 Rd1+ Kg2 > Rd2+ Kh3 Rd5 b7 Rh5+ Kg4 Rb5 > > 10 4.82 -3.18 Rxd3 Qxd3 Qxd3 Rxd3 Rxd3 b6 Rd1+ Kg2 > Rd2+ Kh3 Rd5 b7 Rh5+ Kg4 Rg5+ Kf4 >Rb5 > 10-> 4.84 -3.18 Rxd3 Qxd3 Qxd3 Rxd3 Rxd3 b6 Rd1+ Kg2 > Rd2+ Kh3 Rd5 b7 Rh5+ Kg4 Rg5+ Kf4 >Rb5 > 11 5.86 -- Rxd3 > 11 13.71 -4.43 Rxd3 Qxd3 Qxd3 Rxd3 Rxd3 b6 Kh7 b7 > Rb3 c7 Rxb7 c8=Q Rb1+ Kg2 Rb2+ Kh3 > Rd2 Qc3 > 11-> 13.75 -4.43 Rxd3 Qxd3 Qxd3 Rxd3 Rxd3 b6 Kh7 b7 > Rb3 c7 Rxb7 c8=Q Rb1+ Kg2 Rb2+ Kh3 > Rd2 Qc3 > 12 45.43 -4.43 Rxd3 Qxd3 Qxd3 Rxd3 Rxd3 b6 Kh7 b7 > Rb3 c7 Rxb7 c8=Q Rb1+ Kg2 Rb2+ Kh3 > Rd2 Qc3 Re2 > 12-> 45.47 -4.43 Rxd3 Qxd3 Qxd3 Rxd3 Rxd3 b6 Kh7 b7 > Rb3 c7 Rxb7 c8=Q Rb1+ Kg2 Rb2+ Kh3 > Rd2 Qc3 Re2 > 13 2:23 -4.46 Rxd3 Qxd3 Qxd3 Rxd3 Rxd3 b6 Kh7 b7 > Rb3 c7 Rxb7 c8=Q Rb1+ Kg2 Rb2+ Kh3 > h5 Qf8 f5 Qd6 > > >I then went on to move 47, and found the same thing >as before... .07 seconds into the search Crafty finds that >Rxd3 loses badly and that move never comes back up again. >Is it possible you have a bad bug to play that?? > Huh ? Your PV at ply 7 shows black a rook up, yet -2.87 down ? Looks like you evaluate the two passed pawns as worth almost a queen, unless I am missing something. Of course, you had to do that to solve WAC #2. It's quite correct in this position, and maybe the only way to handle it. This would be very risky if applied too generally. What is the formulation ? Amir
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