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Subject: Re: A Missed Mate in 4

Author: leonid

Date: 06:46:43 03/09/02

On March 07, 2002 at 19:48:08, Slater Wold wrote:

>On March 07, 2002 at 08:05:18, Art Basham wrote:
>
>>Some programs that I have miss this mate in 4..!
>>
>>1. Qc6 wins for white!!
>>
>>[D]2kr1b1r/1pp1qp1p/3p2p1/1P1Pp3/2Q1P1n1/R4N2/1PP2PPP/5RK1 w - -
>
>White(2): setboard 2kr1b1r/1pp1qp1p/3p2p1/1P1Pp3/2Q1P1n1/R4N2/1PP2PPP/5RK1 w - -
>
>White(1): st 180
>search time set to 180.00.
>White(1): go
>              clearing hash tables
>crafty is behind 32.0 on time, reducing by 1/96.
>              time surplus   0.00  time limit 3:00 (3:00)
>         nss  depth   time  score   variation (1)
>                5     0.09   0.61   1. b6 Bh6 2. Ra8+ Kd7 3. Qb5+ c6 4.
>                                    dxc6+ Ke6 5. Qd5+ Kf6 6. cxb7 Kg7
>                5->   0.09   0.61   1. b6 Bh6 2. Ra8+ Kd7 3. Qb5+ c6 4.
>                                    dxc6+ Ke6 5. Qd5+ Kf6 6. cxb7 Kg7
>                6     0.15   0.84   1. b6 Bg7 2. Ra8+ Kd7 3. Qb5+ c6 4.
>                                    dxc6+ Ke6 5. Qd5+ Kf6 6. cxb7 Rb8 7.
>                                    Ra7
>                6->   0.18   0.84   1. b6 Bg7 2. Ra8+ Kd7 3. Qb5+ c6 4.
>                                    dxc6+ Ke6 5. Qd5+ Kf6 6. cxb7 Rb8 7.
>                                    Ra7
>                7     0.50   0.77   1. b6 Bh6 2. Rfa1 Rhf8 3. Ra8+ Kd7
>                                    4. Qb5+ c6 5. dxc6+ Ke6 6. Qd5+ Kf6
>                                    7. cxb7 Kg7
>                7     0.61     ++   1. Qc6!!
>                7     0.62  Mat04   1. Qc6 bxc6 2. dxc6 Kb8 3. Rfa1 Nf6
>                                    4. Ra8#
>         (3)    7->   0.62  Mat04   1. Qc6 bxc6 2. dxc6 Kb8 3. Rfa1 Nf6
>                                    4. Ra8#
>              time=0.84  cpu=148%  mat=-2  n=918801  fh=94%  nps=1093k
>              ext-> chk=38957 cap=7162 pp=6426 1rep=5746 mate=731
>              predicted=0  nodes=918801  evals=98158
>              endgame tablebase-> probes done=0  successful=0
>              hashing-> trans/ref=44%  pawn=98%  used=3%
>              SMP->  split=141  stop=14  data=6/32  cpu=1.25  elap=0.84
>
>mate in 4 moves.

I looked by curiousity this position with my mate solver and found that finding
of mate goes slowly. Even when mate was found by few versions of selective
search time was still identical.

LLchess mate solver. Celeron 600Mhz. No hash.

Mate in 4 moves found and took 0.21 sec. First move goes by white queen C4-C6.

Initial move was real surprise!

Leonid.

Re: A Missed Mate in 4 Heiner Marxen 09:04:23 03/10/02
Re: A Missed Mate in 4 Uri Blass 07:16:04 03/09/02
- Re: A Missed Mate in 4 leonid 08:13:26 03/09/02

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