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Subject: Re: Impressive position! Too easy for computers....

Author: Dann Corbit

Date: 17:30:53 05/21/04

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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 2
>>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.



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