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Subject: Re: 2 very difficult and wild tactical combinations which programs can't see

Author: Uri Blass

Date: 12:50:30 11/02/01

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On November 02, 2001 at 15:23:58, Dann Corbit wrote:

>This one is simply *WAY* too deep for computers.  Besides which, tossing two
>pieces along the way will certainly make it harder for computers.  A negative
>score shows up at ply 12, which is 7 ply beyond the original position, and if we
>toss in null move with r=3 that is 12+7+3 = 22 ply.  Probably in a few months a
>program could solve it.  Or Deep Blue could solve it quickly.  Deep Blue didn't
>use null move.

I believe that programs need less than 22 plies

The line Rxg6+ Kxg6 Nh4+ Kh6 Qe3+ Kh7 Bd3+ is a tactical line and extensions can
help.

I also do not see why so you think that nullnull move with r=3 prune 3 plies.
It prunes 3 plies when there is no threat and I do not think that it is the case
here.

The moves of white(at least Rxg6+ Nh4+ Qe3+ Bd3+) are checks and they are
certainly noy going to be pruned by null move pruning)

I think that the next relevant moves are also not quiet moves so I do not expect
null move to be a problem here.

I expect top programs on good hardware to solve it in less than 24 hours


I am also not sure that Rxg6+ is the only winning move and Junior7 on p200 likes
Qe3 with a big score of more than 1.5.

New game - Junior 7
r1bq1r2/p2np1k1/3p2pR/3pP3/2pP4/5N2/PP2Q1P1/2KR1B2 w - - 0 1

Analysis by Junior 7:

19.Rh1 dxe5 20.Nxe5
  =  (-0.13)   Depth: 3   00:00:00
19.exd6 exd6 20.Qe3 Rb8
  =  (0.06)   Depth: 3   00:00:00
19.Qe3 dxe5 20.Nxe5
  ²  (0.31)   Depth: 3   00:00:00
19.Qe3 dxe5 20.Qg5 Qb6 21.Nxe5 Nxe5
  =  (0.16)   Depth: 6   00:00:00  10kN
19.Qe3!
  ²  (0.46)   Depth: 9   00:00:01  138kN
19.Qe3! dxe5 20.Qg5 Qb6 21.Bd3 Rf6 22.Bxg6 Nf8 23.Be8+
  ²  (0.57)   Depth: 9   00:00:03  394kN
19.Qe3 dxe5 20.Qg5 Qe8 21.dxe5 Rf5 22.Qh4 Qg8 23.Ng5 Rf2
  ±  (0.84)   Depth: 12   00:00:22  2820kN
19.Qe3 dxe5 20.Rxg6+ Kxg6 21.Qg5+ Kf7 22.Qf5+ Kg7 23.Qg4+ Kf6 24.dxe5+ Nxe5
25.Qg5+ Kf7 26.Nxe5+ Ke6 27.Bxc4 Bb7 28.Qg7
  ±  (1.04)   Depth: 14   00:05:04  34924kN
19.Qe3!
  ±  (1.34)   Depth: 15   00:11:19  71839kN
19.Qe3 Rh8 20.Ng5 Nb6 21.Rxh8 Qxh8 22.exd6 e6 23.Qe5+ Kg8 24.Be2 Qh6 25.Qf6 Rb8
  +-  (1.51)   Depth: 16   00:26:43  186231kN
19.Qe3 Rh8 20.Ng5 Nb6 21.Rxh8 Qxh8 22.exd6 e6 23.Qe5+ Kg8 24.Be2 a5 25.Qxh8+
Kxh8 26.Rh1+ Kg8 27.Rh6 a4 28.Rxg6+
  +-  (1.58)   Depth: 17   01:10:21  419599kN


Uri



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