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Subject: Re: Mate in 9

Author: Jeremiah Penery

Date: 17:42:28 06/17/02

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On June 17, 2002 at 20:16:01, John Merlino wrote:

>Here's an amusing little Mate in 9 King chase that I had when testing
>Chessmaster 9000:
>
>[D]r6r/ppp1bQpp/2k1B1q1/4P3/4p3/2P1B3/PP3P1P/2K2R2 w - - 0 20
>
>Chessmaster announces Mate in 10 in three seconds on my PIII-600, then switches
>to Mate in 9 after ten seconds:
>
>Time	Depth	Score	Positions	Moves
>0:00	1/3	5.29	2701		20.Qxe7 b6 21.Qd7+ Kb7 22.Bd5+
>					Kb8 23.Bxa8 Kxa8 24.Qxc7
>0:00	1/3	5.65	5976		20.Rd1 b6 21.Qxe7 Kb7 22.Bd5+ Kb8
>					23.Bxa8 Kxa8 24.Qxc7
>0:00	1/4	5.19	11659		20.Rd1 b6 21.Qxe7 Rhd8 22.Rxd8
>					Rxd8 23.Qxd8 Qxe6 24.Qa8+ Kb5 25.Qxe4
>					Qxa2 26.Qxh7
>0:01	2/5	14.85	74968		20.Rd1 b6 21.Bd5+ Kb5 22.Qxe7 Qd6
>					23.exd6 Raf8 24.Bxe4
>0:01	2/6	15.35	145320		20.Rd1 b6 21.Bd5+ Kb5 22.Qxe7 Qd6
>					23.exd6 c6 24.c4+ Ka6 25.Bxc6
>0:03	3/7	Mate10	374294		20.Rd1 b6 21.Bd5+ Kb5 22.Bc4+ Ka5
>					23.Qxe7 c5 24.Qd7 a6 25.b4+ cxb4
>					26.Rd5+ b5 27.Rxb5+ Ka4 28.Rxb4+
>					Ka5 29.Qa4#
>0:10	3/8	Mate09	1098190		20.Rd1 b6 21.Bd5+ Kb5 22.Bc4+ Ka5
>					23.Qd5+ Bc5 24.Bxc5 Qg5+ 25.Kc2
>					Qd2+ 26.Rxd2 bxc5 27.Qxc5+ Ka4
>					28.Qb4#
>
>Since four of the nine moves are not checking moves, can anybody else do better?

Here's an interesting result.  Not as fast as CM (almost 50 times slower, given
the hardware difference) to find mate, but it finds a shorter one.  This is
modified Crafty 18.15 with singular extensions, AthlonXP 1600MHz:

analyze.Black(1): r6r/ppp1bQpp/2k1B1q1/4P3/4p3/2P1B3/PP3P1P/2K2R2 w - - 0 20
              clearing hash tables
              time surplus   0.00  time limit 30.00 (3:30)
         nss  depth   time  score   variation (1)
                6     0.32     ++   1. Rd1!!
                6     0.77   9.57   1. Rd1 b6 2. Bd5+ Kb5 3. Qxe7 c5 4.
                                    c4+ Ka6 5. Qb7+ Ka5 6. Bd2+ Ka4 7.
                                    Bxe4 <HT>
                6->   0.84   9.57   1. Rd1 b6 2. Bd5+ Kb5 3. Qxe7 c5 4.
                                    c4+ Ka6 5. Qb7+ Ka5 6. Bd2+ Ka4 7.
                                    Bxe4 <HT>
                7     1.54     ++   1. Rd1!!
                7     6.58  14.16   1. Rd1 b6 2. Bd5+ Kd7 3. Bb7+ Qd6 4.
                                    Qf5+ Kd8 5. exd6 cxd6 6. Bxa8 Kc7 7.
                                    Bd5 Kb8 8. Qxe4
                7->   6.78  14.16   1. Rd1 b6 2. Bd5+ Kd7 3. Bb7+ Qd6 4.
                                    Qf5+ Kd8 5. exd6 cxd6 6. Bxa8 Kc7 7.
                                    Bd5 Kb8 8. Qxe4
                8     9.93     ++   1. Rd1!!
                8    16.26  17.17   1. Rd1 b6 2. Bd5+ Kb5 3. Qxe7 Qd6 4.
                                    exd6 c6 5. c4+ Ka6 6. Bxc6 Rad8 7.
                                    Qb7+ Ka5 8. Qxa7+
                8->  16.82  17.17   1. Rd1 b6 2. Bd5+ Kb5 3. Qxe7 Qd6 4.
                                    exd6 c6 5. c4+ Ka6 6. Bxc6 Rad8 7.
                                    Qb7+ Ka5 8. Qxa7+
                9    26.31     ++   1. Rd1!!
                9    46.19  Mat09   1. Rd1 b6 2. Bd5+ Kb5 3. Qxe7 a5 4.
                                    Qxc7 Rac8 5. Bc4+ Ka4 6. Bb3+ Kb5 7.
                                    Rd5+ Ka6 8. Bc4+ b5 9. Bxb5#
                9->  48.39  Mat09   1. Rd1 b6 2. Bd5+ Kb5 3. Qxe7 a5 4.
                                    Qxc7 Rac8 5. Bc4+ Ka4 6. Bb3+ Kb5 7.
                                    Rd5+ Ka6 8. Bc4+ b5 9. Bxb5#
               10     1:15  Mat08   1. Rd1 b6 2. Bd5+ Kb5 3. Qxe7 a5 4.
                                    Qxc7 Rac8 5. Bc4+ Ka4 6. Kb1 Rxc7 7.
                                    b3+ Ka3 8. Bc1#
               10->   1:21  Mat08   1. Rd1 b6 2. Bd5+ Kb5 3. Qxe7 a5 4.


Is the given line correct?



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