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Subject: Re: Can anyone find this Mate in Eight?

Author: Bernhard Bauer

Date: 23:51:16 04/09/00

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On April 08, 2000 at 11:55:01, tony worsman wrote:

>Hi Folks,
>Ive been trying to find the solution to this endgame study
>for a couple of days now,
>A direct mate in 8 apparently, The study is by Helmut KLUG and
>Wolfgang BOR from 1976.
>
>
>r7/p1pRpP1n/K3Pp1b/5B1n/4NkP1/2B5/2N1Pp2/1b6 w - -
>
>Amy favours Bd2+, as do all the programs i've used:-
>
>
>10    2:47     +++  1. Nxf2
>10    3:45  +5.328  1. Nxf2 Ng5 2. Nd3+ Kg3 3. Na3 Ba2 4. gxh5 Bxe6 5. Bxe6
>                    Nxe6 6. Rxe7
>10    4:03     +++  1. Bd2+
>10    5:50  +5.336  1. Bd2+ Ke5 2. Rd3 f1=Q 3. Bc3+ Kf4 4. e3+ Kf3 5. Nd2+
>                    Kg3 6. Nxf1+ Kg2 7. Be1
>10    8:01  +5.336  1. Bd2+ Ke5 2. Rd3 f1=Q 3. Bc3+ Kf4 4. e3+ Kf3 5. Nd2+
>                    Kg3 6. Nxf1+ Kg2 7. Be1
>11    9:23     +++  1. Bd2+
>11   15:46  +6.032  1. Bd2+ Ke5 2. Nxf2 Bxc2 3. Bc3+ Kf4 4. Bxc2 Ng3 5. Bxh7
>                    Ke3 6. Bd2+ Kxf2
>11   22:21  +6.032  1. Bd2+ Ke5 2. Nxf2 Bxc2 3. Bc3+ Kf4 4. Bxc2 Ng3 5. Bxh7
>                    Ke3 6. Bd2+ Kxf2
>12   40:08  +6.160  1. Bd2+ Ke5 2. Nxf2 Bxc2 3. Bc3+ Kf4 4. Bxc2 Ng7 5. Bxh7
>                    Nxe6 6. Bd2+ Kg3 7. Ne4+ Kxg4
>12   61:07  +6.160  1. Bd2+ Ke5 2. Nxf2 Bxc2 3. Bc3+ Kf4 4. Bxc2 Ng7 5. Bxh7
>                    Nxe6 6. Bd2+ Kg3 7. Ne4+ Kxg4
>Nodes = 251089260, QPerc: 53 %, time = 10800 secs, 23.2 kN/s
>Extensions: Check: 43061050  DblChk: 476724  DiscChk: 3367359  SingReply:
>3235142
>            Recapture: 1904421   Passed Pawn: 114340   Zugzwang: 0
>Hashing: Trans: 4704498/116504568 = 4 %   Pawn: 95869890/96020430 = 10 %
>         Eval: 38272659/134293089 = -3 %
>EGTB Hits/Probes = 0/0
>Hashtable 1:  entries = 524288, use = 492978
>
>
>And here is the end of SOS's debug file after 20 hours on the job, yet no mate.
>Using a P1-200MMX.
>
>
>71920040 <first :   15   1022 7181475 3121836329 Bd2+ Ke5 Ba5 Rc8 f8Q f1Q Bc3+
>Kf4 Qxh6+ Ng5 Nxg5 fxg5 gxh5 Kg3 Qxg5+ Kh2 Kxa7   (44 knps)
>72234160 <first :   15   1023 7212892 3134278845 Bd2+ Ke5 Ba5 Rc8 f8Q f1Q Bc3+
>Kf4 Qxh6+ Ng5 Nxg5 fxg5 gxh5 Kg3 Qxg5+ Kh2 Kxa7   (44 knps)
>72541690 <first :   15   1024 7243645 3146138431 Bd2+ Ke5 Ba5 Rc8 f8Q f1Q Bc3+
>Kf4 Qxh6+ Ng5 Nxg5 fxg5 gxh5 Kg3 Qxg5+ Kh2 Kxa7   (44 knps)
>72856630 <first :   15   1025 7275139 3158368629 Bd2+ Ke5 Ba5 Rc8 f8Q f1Q Bc3+
>Kf4 Qxh6+ Ng5 Nxg5 fxg5 gxh5 Kg3 Qxg5+ Kh2 Kxa7   (44 knps)
>72906450 >first : exit
>72906510 >first : force
>72906560 <first : Stopped by user input
>72906560 <first :  PV: (1025) c3d2 f4e5 d2a5 a8c8 f7f8q f2f1q a5c3 e5f4 f8h6
>h7g5 e4g5 f6g5 g4h5 f4g3 h6g5 g3h2 a6a7
>72906620 <first :    time used: 20:13:21
>
>I would be interested if anyone can find a mate in 8 here
>
>Regards and Happy Hunting :o)
>
>Tony Worsman

Crafty v17.10 takes a while to finish depth=12.
But if you lower the extensions, for example set
ext/onerep=0.5
ext/incheck=0.5
ext/recapture=0.75
ext/pushpp=0.75
ext/threat=0.75
ext/singular=0.75
Crafty finds the mate in 2 min.

         (3)   11->  59.16   6.04   1. Bd2+ Ke5 2. Nxf2 Bxc2 3. Bc3+ Kf4
                                    4. Bxc2 Nf8 5. gxh5 Nxd7 6. exd7 Kg3
                                    7. Nh1+ Kf4 8. Nf2
               12     1:40     ++   1. Bd2+!!
         (2)   12     1:58  Mat08   1. Bd2+ Ke5 2. Ba5 Rc8 3. f8=N Nxf8
                                    4. Bc3+ Kf4 5. Rd5 f1=N 6. Rd3 Ne3
                                    7. Rxe3 Bxc2 8. Rf3#
               12->   2:20  Mat08   1. Bd2+ Ke5 2. Ba5 Rc8 3. f8=N Nxf8
                                    4. Bc3+ Kf4 5. Rd5 f1=N 6. Rd3 Ne3
                                    7. Rxe3 Bxc2 8. Rf3#
              time=2:20  cpu=207%  mat=-1  n=73204596  fh=94%  nps=519771
              ext-> checks=3996234 recaps=113962 pawns=90498 1rep=209946
thrt:41681
              predicted=0  nodes=73204596  evals=9473567
              endgame tablebase-> probes done=0  successful=0
              SMP->  split=498  stop=51  data=9/64  cpu=4:52  elap=2:20

Kind regards
Bernhard



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