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Subject: Re: Difficult position for older computers

Author: Hans Havermann

Date: 19:18:55 02/14/99

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On February 10, 1999 at 09:23:53, Alain Lyrette wrote:

>Taken from the february issue of Chess life:
>L.Evans-C.Pilnick 1946

>None of my little computers(Fidelity,Saitek,Radio
>Shack)can find the solution in 2 hours(Bxg6!).I don't doubt that pc programs of
>today will resolve that problem quite easily but how much time will they
>take?

On my G3, MacChess 5.0.1 finds the correct move at depth 8, after 51 seconds:

2r2rk1/p3bb1p/2n1Q1p1/q2pP3/3P1P2/p1NB1NR1/1P4P1/1K1R4 w - -

02/01|00:00:00|        4179|-124| Qd7 axb2 Kxb2 Nxe5 fxe5 Qxc3+
03/01|00:00:00|       12160|-131| Qd7 axb2 Kxb2 Qb4+ Kc2 Nxd4+
03/02|00:00:00|       18068|-129| Qf5 axb2 Kxb2 Qb4+ Kc2 Nxd4+
04/01|00:00:01|       42440|-179| Qf5 axb2 Na2 Kh8 Qd7
04/02|00:00:01|       59076|-177| Qd7 axb2 Na2 Rc7 Qf5
04/04|00:00:01|       81050|-173| Qg4 axb2 Na2 Qa3 e6
05/01|00:00:01|      114207|-173| Qg4 axb2 Na2 Qa3 e6
06/01|00:00:02|      397904|-301| Qg4 axb2 e6 Qa1+ Kc2 Nb4+ Kd2 Nxd3 exf7+ Kxf7
07/01|00:00:04|     1075947|-302| Qg4 axb2 e6 Qa1+ Kc2 Nb4+ Kd2 Nxd3 exf7+ Kxf7
                                  Ng5+ Bxg5 Rxd3
08/01|00:00:18|     5480738|-424| Qg4 axb2 e6 Be8 Kxb2 Qb4+ Ka1 Qxc3+ Kb1 Qb3+
                                  Kc1 Nxd4+
08/03|00:00:40|    12110933|-367| Qd7 axb2 e6 Qa1+ Kc2 Nxd4+ Kd2 Qc1+ Rxc1 Nb3+
                                  Ke2 bxc1=Q exf7+ Kxf7 Qxd5+
08/13|00:00:51|    15425542|-337| Bxg6 Bxe6 Bxh7+ Kh8 Rh1 Rxf4 Bf5+ Bh4 Bxe6 a2+
                                  Nxa2

Letting the program run a little longer...

09/01|00:01:01|    18530506|-313| Bxg6 Bxe6 Bxh7+ Kh8 Rh1 Rxf4 Bf5+ Bh4
                                  Bxe6 axb2 Rxh4+ Rxh4 Nxh4
10/01|00:02:14|    41816978|-120| Bxg6 Bxe6 Bxh7+ Kh8 Rh1 Bh4 Nxh4 Nxe5 Bf5 Ng4
                                  Nf3+ Kg7 Bxe6
11/01|00:08:25|   159924704| +16| Bxg6 Bxe6 Bxh7+ Kh8 Rh1 Rxf4 Bf5+ Bh4 Nxh4 a2+
                                  Nxa2 Rf1+ Rxf1 Nxd4 Re3
12/01|00:20:12|   382234617| +48| Bxg6 Bxe6 Bxh7+ Kh8 Rh1 Bh4 Nxh4 Nxe5
                                  fxe5 Rxc3 Ng6+ Kg7 bxc3 a2+ Ka1 Rc8
13/01|01:24:54|  1617690286|+106| Bxg6 Bxe6 Bxh7+ Kh8 Rh1 Bh4 Nxh4 Rf7 Bg6 a2+
                                  Nxa2 Rcc7 Nf3+ Kg7 Bxf7+ Kxf7 Nc3
14/01|05:16:59|  6042020580|+201| Bxg6 Bxe6 Bxh7+ Kh8 Rh1 Bh4 Bd3 Rxf4 Nxh4 a2+
                                  Ka1 Bg4 Ng6+ Kg8 Nxf4 Nxe5 dxe5
15/01|70:08:10| 79828048405|+323| Bxg6 Bxe6 Bxh7+ Kh8 Rh1 Bh4 Bd3 Rxf4 Nxh4 a2+
                                  Ka1 Bg4 Ng6+ Kg7 Nxf4 Nxd4 Rxg4+ Kf7 Rh7+ Ke8
                                  Nxa2

The improvements in evaluation values increase steadily with depth (with the
transition from losing to winning score occurring at 11-ply after eight and a
half minutes). It took 67 hours [316211 nodes/second; maximum depth probed:
92-ply] to get from the best 14-ply eval to the end of the 15-ply search. I
wouldn't have done this if I had known it was going to take so long.



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