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Subject: Re: Yace sacrifice: a wide, deep analysis with Fritz

Author: Roy Eassa

Date: 14:54:35 09/10/01

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>[D] rnb1kb1r/1pq2p1p/p4P2/4pP2/2B5/2NQ4/PPP2p1P/2KR3R w kq -
>
>but I'm not sure. Crafty doesn't like this sac even after 30
>minutes search. Crafty also takes a long time to find 17. Ne4+,
>and it was still failing high after 30 minutes (on a PIII/733),
>with a - score for White. By move 21, it sees White winning.
>
>I'm not sure Black has a defense. In analysis mode, Crafty thought
>18 .. Bb7 a mistake and prefers .. Bh6.


With assistance from Fritz 6 on Athlon 1.2 GHz, I think Black missed two chances
to hold.  First, 2... Ke8! instead of 2... Kxf6, and second, 6... Rd8! instead
of 6... Bf4:

1.Bxf7+!? Kxf7 2.Qd5+ Kxf6?

[2...Ke8! 3.f7+ Ke7 4.f6+ Kxf6 5.Ne4+ Ke7 6.Nd6
   (6.Qd2 Qb6 7.Nd6
      (7.Qg5+ Kxf7 8.Rhf1 Bh6 9.Rxf2+ Qxf2
         (9...Ke8 10.Rd8+ Qxd8 11.Qxh6 Qd4 12.Qf6 Qxe4 13.Qxh8+ Kd7 14.Rd2+ Kc6
            (14...Ke7)
          15.Qxc8+ Kb6
            (15...Kb5? 16.a4+! Kb6
               (16...Kxa4 17.Qc5 Qb4 18.Qxe5 Qxd2+ 19.Kxd2 Nc6 20.Qc5 Nb4 21.b3+
Ka3 22.Kc1!
                  (22.Qa5+ also wins)
                22...b5 23.c3 a5 24.cxb4 a4 25.bxa4 Kb3 26.Qd5++-)
             17.a5+! Kxa5 18.Qc5+ b5 19.Qc7+ Ka4 20.b3+ Kb4 21.Kb2 Nc6 22.c3+
Kc5 23.b4+ mates)
          16.Rd6+ Nc6 17.Qxa8= and Black should take the perpetual check)
       10.Nd6+ Ke6 11.Qxh6+ Qf6 12.Qh3+ Ke7 13.Nxc8+ Ke8 and the best White can
do is a perpetual check)
    7...Bh3! 8.Qg5+ Ke6 9.Ne4 Nd7 10.Qh5 Qe3+ 11.Kb1 Bf5 12.Ng3 Bxc2+ 13.Kxc2
Nf6 14.Qf5+ Kxf7 15.Rhf1 Qf4 16.Rd7+
      (16.Qd3 Rc8+ 17.Kb1 b5-+)
    16...Be7-+)
 6...Bh6+ 7.Kb1 Bf4 8.Qg2 Rf8-+ Black seems to survive the attack 9.Qxf2
   (9.Rhf1 Nc6 10.Rxf2 Qxd6! 11.Rxd6 Kxd6 12.Qg7 Bf5 13.Rxf4 exf4 14.Qf6+ Be6
15.Qxf4+ Kd7-+)
 9...Qxd6! 10.Rxd6 Kxd6 11.Rd1+ Ke6 12.Qh4
   (12.Qf3 Kxf7 13.Qd5+ Kg7 14.Rg1+ Kh8 15.Qg2 Bh6-+)
 12...Nd7 13.Qh3+ Ke7 14.Qxh7 Nf6-+]

3.Ne4+

[3.Qf3(!) 3...Bh6+ 4.Kb1 Kg7 5.Qg4+ Kf8 6.Qh4 Qg7 7.Rd8+ Kf7 8.Qh5+ Ke7 9.Rxh8
Qxh8 10.Qxh6 Qg8 11.Rd1 Nd7 12.Ne4 Qf7 13.Qd6+ Ke8 14.f6 h6 15.Qd2 Qe6 16.Qxh6
Kd8 17.Qf8+ Kc7 18.Qe7 Qc6 19.f7 Kb6 20.Nxf2 Qf3 21.Rd6+ Ka7 22.Nd3 Qh1+
23.Nc1±]

3...Ke7

[3...Kxf5? 4.Kb1! Bh6 5.Rhf1 Bf4
   (5...Be3 6.Nxf2 Kg6 7.Qg2+ Kf7 8.Ne4+ Bf4 9.Rg1 Bh6 10.Rd6 Qxd6 11.Nxd6++-)
 6.Rxf2 Qe7
   (6...Rd8 7.Rxf4+ Kxf4 8.Rf1++-)
 7.Rxf4+ Kxf4 8.Rf1+ Kg4 9.Nf6+ Qxf6
   (9...Kg5? 10.Qf3 Kg6 11.Qh5+ Kg7 12.Qg5+ and mate in 7)
 10.Rxf6+- and mate soon]

4.Nd6

[4.Rhf1 Bxf5 5.Rxf2 Bh6+ 6.Kb1 Rd8-+;
 4.f6+ Ke8 5.f7+ Ke7 6.Nd6 transposes to the line in the notes after 2... Ke8!,
in which Black survives.]

4...Bh6+ 5.Kb1 Kf6 6.Qf3 Bf4

[6...Rd8! 7.Qh3
   (7.Qh5 Be3 8.Qh4+ Kg7 9.Qg3+ Kf6
      (9...Kf8? 10.Qxe5 Qg7 11.f6+-)
    10.Qh4+ draw
      (10.Ne4+ Kf7 11.Qxe3 Nc6 12.Qh6 Bxf5 13.Qf6+ Kg8 14.Qxf5 Rxd1+ 15.Rxd1 Rf8
is OK for Black);
    7...Kg7
     a)7...Rxd6! 8.Qxh6+ Ke7 9.Qg7+
         (9.Qxh7+ Kd8 10.Qg8+ Kd7 11.Qe6+ Kc6 12.Qc4+
            (12.Rxd6+ Qxd6 13.Qxc8+ Kb6-+)
          12...Kb6 13.Qb4+ Ka7 14.Rxd6 Bxf5 15.Rd2 Nc6 16.Qc5+ b6 17.Qxf2
Rf8-/+;
       9...Kd8 10.Qxe5 Bxf5 11.Rxd6+
         (11.Qxd6+ Qxd6 12.Rxd6+ Kc7 13.Rf6 Be4=+ is OK for Black;
          11.Qxf5 Nd7 12.Qxh7 Qc5 13.Qg8+ Kc7 14.Qxa8 Rxd1+ 15.Rxd1 Qb5-+)
       11...Nd7 12.Ka1
         (12.Qf6+ Ke8 13.Re6+ Bxe6 14.Qxe6+ Kf8 15.Rf1 Kg7 16.Rxf2 Kh8 and it
looks like Black survives to win.)
       12...Qxc2 13.Rhd1 Rc8 14.Rxd7+ Bxd7 15.Qf6+ Ke8 16.Qe5+ draw;
     b)7...Bg5? 8.Ne4+ Kg7 9.Nxg5 Rxd1+ 10.Rxd1 h6 11.Ne4 Nc6 12.Rd6 Bxf5
13.Qxf5 Qf7 14.Rf6 Rf8 15.Qg4+ Kh7 16.Rxf7+ Rxf7 17.Nxf2 Rxf2 18.Kc1±;
    8.f6+ Kg6 9.Qg3+ Kxf6 10.Qxf2+ Bf4 11.Qh4+ Ke6 and White can do no better
than a perpetual check.]

7.Qg4 Qg7

[7...Nc6? 8.Qh4+ Bg5 9.Ne4+ Kxf5 10.Qxg5+!
   (10.Nxg5? Rg8!
      (10...Nd4? 11.Rd2 Kg6 12.Ne4 Qc6 13.Qg5+ Kf7 14.Rxf2++-;
       10...h5? 11.Rhf1 Kg6 12.Ne4 Qe7 13.Rd6+ Kg7 14.Rf6! Rh7 15.Qxf2 Be6
16.Ng5+-)
    11.Qxf2+ Kxg5 12.Rhg1+ Bg4 13.Rxg4+ Kxg4 14.Rg1+ Kh5 15.Qf5+ Kh4 draw;
 10...Kxe4 11.Qh4+ Kf5 12.Rhf1 Nd4 13.Rxf2+ Ke6 14.Rf6+ Kd5 15.c3 Bf5+ 16.Rxf5
Raf8 17.Qxd4+ Ke6 18.Qd5+! Kxf5 19.Rf1+ Kg5 20.Qg2+ Kh4 21.Qg3+ Kh5 22.Rg1+-]

8.Qh4+ Bg5 9.Ne4+ Kxf5 10.Qxf2+

[10.Ng3+ Kg6 11.Rd6+ Qf6!
   (11...Kf7? 12.Qc4+ Ke7 13.Qc7+ Nd7 14.Nf5+ Kf8 15.Nxg7 Kxg7 16.Rxd7+ Bxd7
17.Qxd7+±)
 12.Qe4+ Kf7 13.Rxf6+ Bxf6 14.Rf1 Be6 15.Rxf2
   (15.Nh5 Nd7 16.Nxf6 Kxf6 17.Rxf2+ Ke7 18.Qb4+ Kd8 19.Qxb7 Rb8 20.Qxa6 Rg8
21.b3 Rb6=)
 15...Nd7 16.Qxb7 Rab8 17.Qxa6 Ra8 18.Qd3 Bxa2+ 19.Kc1 Be6 20.Ne4 unclear!]

10...Bf4

[10...Ke6? 11.Nxg5+ Qxg5
   (11...Ke7 12.Qc5+ Kf6 13.Ne4+ mates soon)
 12.Rhf1 Qf4 13.Qg2+-]

11.Rhg1 Qxg1

[11...Qh6 12.Qg2! Ke6 13.Rd6+ Kf7 14.Rxh6 Bxh6 15.Qf3+ Bf4 16.Qh5+ Ke6 17.Rg7
Kd5 18.Qf3 mates soon;
 11...Qf8 12.Qg2 Ke6 13.Qg4+ Ke7 14.Qh4+ and White mates.]

12.Nd6+ Kf6 13.Rxg1

[13.Qxg1 Nc6 14.Qf2=]

13...Nc6

[13...Ke6 14.Ne4 Nc6 transposes to the line below]

14.Ne4+ Ke6 15.Qg2!

[15.Qc5 Rd8 16.Qc4+ Kf5 17.Ng5 Bxg5 18.Qg4+ Kf6 19.Qxg5+ Ke6 20.Qh6+ Kd5 21.Rd1+
Nd4 22.Rxd4+ exd4 23.Qg5+ Bf5 24.Qxf5+ Kc6 25.Qxh7² but unclear (somebody
comment?)]

15...Nd4

[15...Rd8 16.c4! Rf8
   (16...Nd4 17.Qh3+ Nf5 18.Qxh7 Ne7 19.Rg7 Rd1+ 20.Kc2 Rc1+ 21.Kd3 Rd1+ 22.Ke2
Rd7 23.Qh5+-;
    16...Ne7 17.Qh3+ Kf7 18.Qxh7+ Ke6 19.Rg7 transposes)
 17.Qh3+ Ke7 18.Rg7+ Rf7 19.Qa3+ Ke6 20.Qd6+ Kf5 21.Ng3+ Bxg3 22.Rxf7+ Kg4
23.Qd3 and mate soon]

16.Qg7! Bd7 17.Qf6+ Kd5 18.Re1! Rac8 19.Qd6+ Kc4 20.Qxd7+-



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