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Subject: Re: One easy mate to solve. Correction!

Author: Dann Corbit

Date: 14:00:52 09/12/01

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On September 12, 2001 at 16:45:15, Uri Blass wrote:

>On September 12, 2001 at 16:08:11, Dann Corbit wrote:
>
>>On September 12, 2001 at 10:45:44, leonid wrote:
>>
>>>On September 12, 2001 at 10:34:41, leonid wrote:
>>>
>>>>[D]Q6r/1prpbqk1/1Q4q1/1Q1nn1p1/1Q1NN1p1/1R4q1/1BBQQRp1/K6b w - -
>>>>
>>>>Please indicate your result.
>>
>>According to chest, it's not a mate in 8.
>>
>>Crafty can't spot it, but I did not expect 17+ ply to be exhausted:
>>EPD Kit revision date: 1996.04.21
>>unable to open book file [e:\crafty\release/books.bin].
>>hash table memory = 192M bytes.
>>pawn hash table memory = 80M bytes.
>>EGTB cache memory = 32M bytes.
>>draw score set to    0.00 pawns.
>>choose from book moves randomly (using weights.)
>>choose from 5 best moves.
>>book learning enabled
>>result learning enabled
>>position learning enabled
>>threshold set to 9 pawns.
>>5 piece tablebase files found
>>19045kb of RAM used for TB indices and decompression tables
>>
>>Crafty v18.10
>>
>>White(1): st 999
>>search time set to 999.00.
>>White(1): epdpfga \t.epd t.out
>>PFGA: EPD record: 1
>>middle-game phase
>>              clearing hash tables
>>              time surplus   0.00  time limit 16:39 (16:39)
>>         nss  depth   time  score   variation (1)
>>                1     0.03  26.76   1. Rxf7+ Qxf7
>>                1->   0.05  26.76   1. Rxf7+ Qxf7
>>                2     0.05  26.75   1. Rxf7+ Qxf7 2. Rxg3 Rxa8+
>>                2->   0.19  26.75   1. Rxf7+ Qxf7 2. Rxg3 Rxa8+
>>                3     0.20     --   1. Rxf7+
>>                3     0.23  24.14   1. Rxf7+ Qxf7 2. Qxh8+ Kxh8 3. Qh6+
>>                                    Kg8 4. Rxg3 Bxb4 5. Qdxg5+
>>                3->   0.63  24.14   1. Rxf7+ Qxf7 2. Qxh8+ Kxh8 3. Qh6+
>>                                    Kg8 4. Rxg3 Bxb4 5. Qdxg5+
>>                4     0.79  24.14   1. Rxf7+ Qxf7 2. Qxh8+ Kxh8 3. Qh6+
>>                                    Kg8 4. Rxg3 Bxb4 5. Qdxg5+
>>                4->   2.13  24.14   1. Rxf7+ Qxf7 2. Qxh8+ Kxh8 3. Qh6+
>>                                    Kg8 4. Rxg3 Bxb4 5. Qdxg5+
>>                5     2.17     ++   1. Rxf7+!!
>>                5     3.91  26.23   1. Rxf7+ Qxf7 2. Qxh8+ Kxh8 3. Rxg3
>>                                    Bxb4 4. Qh6+ Kg8 5. Qdxg5+ Ng6 6. Qbxd5
>>                5->   8.16  26.23   1. Rxf7+ Qxf7 2. Qxh8+ Kxh8 3. Rxg3
>>                                    Bxb4 4. Qh6+ Kg8 5. Qdxg5+ Ng6 6. Qbxd5
>>                6     8.37     ++   1. Rxf7+!!
>>                6    19.60  26.77   1. Rxf7+ Qxf7 2. Qxh8+ Kxh8 3. Qh6+
>>                                    Kg8 4. Nf6+ Nxf6 5. Qdxg5+ Ng6 6. Qhxg6+
>>                                    Qxg6 7. Qxg6+ Kh8 8. Rxg3 Bxb4 9. Qxb4
>>                6->  38.74  26.77   1. Rxf7+ Qxf7 2. Qxh8+ Kxh8 3. Qh6+
>>                                    Kg8 4. Nf6+ Nxf6 5. Qdxg5+ Ng6 6. Qhxg6+
>>                                    Qxg6 7. Qxg6+ Kh8 8. Rxg3 Bxb4 9. Qxb4
>>                7    40.59     ++   1. Rxf7+!!
>>                7     2:39  28.64   1. Rxf7+ Qxf7 2. Nf5+ Qxf5 3. Qxh8+
>>                                    Kxh8 4. Qh6+ Qh7 5. Qxh7+ Kxh7 6. Nxg3+
>>                                    Ng6 7. Qbd4 Bc5
>>                7->   3:37  28.64   1. Rxf7+ Qxf7 2. Nf5+ Qxf5 3. Qxh8+
>>                                    Kxh8 4. Qh6+ Qh7 5. Qxh7+ Kxh7 6. Nxg3+
>>                                    Ng6 7. Qbd4 Bc5
>>                8     3:37     ++   1. Rxf7+!!
>>              time=16:39  cpu=99%  mat=22  n=589487968  fh=99%  nps=590k
>>              ext-> chk=80125742 cap=1032919 pp=36146 1rep=5779692 mate=87
>>              predicted=0  nodes=589487968  evals=3796048
>>              endgame tablebase-> probes done=0  successful=0
>>
>>So tell me, what's the solution?
>>
>>Pretty diagram, by the way.
>
>Crafty can solve it.
>
>I gave it the first move in the main line(Rxf7+)
>and after every legal move it can see a forced mate
>
>1.Rxf7+ Qxf7 [1...Kxf7 2.Qxd5+ #4/5  2 ;
>1...Kh6 2.Qxh8# #1/5  2 ;
>1...Nxf7 2.Nf5+ #6/5  2 ] 2.Qxh8+ #10/8  1:47
>
>1.Rxf7+ Qxf7 is the main line and it needs some time to
>see mate in 10 after 1.Rxf7+ Qxf7
>
>It has no problem to see shorter mate after all the other legal moves.

Unforutnately, that's NOT the solution.  It's Qxg6 according to leonid.



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