Author: Bas Hamstra
Date: 05:17:11 05/22/04
Go up one level in this thread
On May 21, 2004 at 20:30:53, Dann Corbit wrote: >On May 21, 2004 at 20:25:04, Uri Blass wrote: > >>On May 21, 2004 at 20:17:21, Mike Byrne wrote: >> >>>On May 21, 2004 at 19:32:33, George Tsavdaris wrote: >>> >>>>Black threatens mate and white's Queen. What white should play? >>>>Give it's Queen of course! Qf4!! and white is winning. >>>> >>>> Impressive for humans but not for computers, as any chess engine can solve >>>>this in seconds.... >>>> >>>>[D]1kbr3r/pp6/8/P1n2ppq/2N3n1/R3Q1P1/3B1P2/2R2BK1 w - - 0 1 >>> >>> >>>Black(1): mt 24 >>>max threads set to 2 >>>Black(1): 1kbr3r/pp6/8/P1n2ppq/2N3n1/R3Q1P1/3B1P2/2R2BK1 w - - 0 1 >>>White(1): go >>> clearing hash tables >>> time surplus 29.92 time limit 1666:39 (1666:39) >>> depth time score variation (1) >>>starting thread 1 >>> 1 0.00 2.84 1. Qxc5 >>> 1-> 0.00 2.84 1. Qxc5 >>> 2 0.00 -1 1. Qxc5 >>> 2 0.00 -Mat01 1. Qxc5 Qh1# >>> 2 0.00 -9.26 1. Qe5+ Nxe5 2. Nxe5 Rxd2 3. Rxc5 >>> 2 0.02 -8.25 1. Bg2 Nxe3 2. Rxe3 >>> 2-> 0.02 -8.25 1. Bg2 Nxe3 2. Rxe3 >>> 3 0.02 -8.25 1. Bg2 Nxe3 2. Rxe3 >>> 3-> 0.04 -8.25 1. Bg2 Nxe3 2. Rxe3 >>> 4 0.04 -8.62 1. Bg2 Nxe3 2. Rxe3 Qh2+ 3. Kf1 Nd3 >>> 4-> 0.05 -8.62 1. Bg2 Nxe3 2. Rxe3 Qh2+ 3. Kf1 Nd3 >>> 5 0.07 -8.58 1. Bg2 Nxe3 2. Rxe3 Nd3 3. Rc2 >>> 5 0.07 -8.29 1. Qf4+ gxf4 2. Bxf4+ Ka8 3. Nb6+ axb6 >>> 4. axb6+ Na6 5. Rxc8+ Rxc8 6. Rxa6+ >>> bxa6 7. Bg2+ Rc6 8. Bxc6# >>> 5-> 0.08 -8.29 1. Qf4+ gxf4 2. Bxf4+ Ka8 3. Nb6+ axb6 >>> 4. axb6+ Na6 5. Rxc8+ Rxc8 6. Rxa6+ >>> bxa6 7. Bg2+ Rc6 8. Bxc6# (s=9) >> >> >>What is this? >>Crafty evaluates mate as -8.29 pawns? >> >>Movei always evaluates mate as Mate-ply when ply is the number of plies from the >>root position. > >Crafty has not resolved the mate yet. Crafty is sure of a win (at +8 pawns, it >is almost impossible to lose). But a 5 ply search with 8 hundredths of a second >has not determined for a certainty that there is no alternative to checkmate. > >It is also possible to see a pv with a # in it that is not a checkmate at all. >So that knife cuts both ways. I don't agree at all. IMO it's kind of ridiculous to let a PV end in checkmate without showing a mate score. What is happening here is that Crafty doesn't have a clue about the checkmate (because of how it's qsearch operates) and so does not evaluate it. However the PV print routine DOES recognize it. Bas.
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