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

Author: Uri Blass

Date: 13:45:15 09/12/01

Go up one level in this thread


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.

Uri



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