Author: Dieter Buerssner
Date: 07:28:21 03/16/01
Go up one level in this thread
On March 15, 2001 at 21:42:19, Dann Corbit wrote:
>On March 15, 2001 at 08:35:14, Sune Larsson wrote:
>
>> r4rk1/1bp3pp/p3Pp2/1pb2P1Q/5B1N/1Pq1p1PK/P6P/R2R4 w - - 0 1
>>
>> Moroni-Fletcher, London 1933
>>
>>
>> In this position white is aiming for the king. At his disposal there is
>> a very straight forward way of finishing his opponent off. Without any sort
>> of hesitation or caring about the material balance. Just go!
>>
>>
>> Test: This position is for the attacker. Show some tactical brilliance!
>> The choice of Moroni further down.
>>
>>
>> Sune
>>> Moroni-Fletcher
>> London 1933
>>
>> 1.Rd7! Qxa1 2.Rxg7+! Kxg7 3.Bh6+ Kh8 4.Ng6+! hxg6 5.fxg6! Qf1+ 6.Kh4 Qf3
>> 7.Bg7+! Kxg7 8.Qh7 mate
>
>There is no mate in 8, according to Chest. Here is the (nul) output of Chest:
>E:\chest-3.19>chest319 -b -M 256 -Z 8 t.epd
>
>I am currently checking for a mate in 9
I think, it is almost impossible to find a forced mate by normal means in this
position. However after 1.Rd7 Qxa1:
2243326 17.703 2.65 10. 2.Rxg7+ Kxg7 3.Bh6+ Kh8 4.Ng6+ hxg6 5.fxg6 Kg8
6.Bxe3 Qf1+ 7.Kh4 Qc4+ 8.bxc4
2400484 19.297 3.05 11++ 2.Rxg7+ Kxg7 3.Bh6+ Kh8 4.Ng6+ hxg6 5.fxg6 Kg8
6.Bxe3 Qf1+ 7.Kh4 Qc4+ 8.bxc4 Rf7 9.exf7+ Kg7
10.f8=Q+ Kxf8 11.Bxc5+ Kg8 {581}
3639522 28.376 Mat11 11t 2.Rxg7+ Kxg7 3.Bh6+ Kh8 4.Ng6+ hxg6 5.fxg6 Kg8
6.Bxe3 Qf1+ 7.Kh4 Qh3+ 8.Kxh3 Bg2+ 9.Kh4H Rf7H
10.exf7+H Kf8H 11.Bxc5+H Kg7H 12.Qh7#H {661}
4232328 32.886 Mat11 11. 2.Rxg7+ Kxg7 3.Bh6+ Kh8 4.Ng6+ hxg6 5.fxg6 Kg8
6.Bxe3 Qf1+ 7.Kh4 Qh3+ 8.Kxh3 Bg2+ 9.Kh4 Rf7
10.exf7+ Kf8 11.Bxc5+ Kg7 12.Qh7# {661}
and soon:
18067469 1:54.2 Mat10 13. 2.Rxg7+ Kxg7 3.Bh6+ Kh8 4.Ng6+ hxg6 5.fxg6 Kg8
6.Bg7 Bg2+ 7.Kxg2 Qg1+ 8.Kxg1 e2+ 9.Kg2 e1=N+
10.Kh3 Kxg7 11.Qh7# {-529}
This didn't change until iteration 16 was completed.
I experimented a bit wit this position, and after any response to Rd7, that I
tried, I could come up with a forced mate sooner or later. Usually the mating
was between move 15 and 20. But I did not try to shorten the mate, I just
showed, that there is no refutation for black. But after some time, I lost
patience. After Yace knew the bad lines, it showed a score of -5.7 in favor of
white after Rd7.
705778455 1:18:35 -5.68 12t 1...Bg2+ 2.Nxg2 Rae8 3.Rad1H Be7H 4.Rxc7H Qb2H
{HT} {-340}
However, even after 1 hour of thinking in the root position, Yace will still
come up with Rac1. It thought for a very long time at Rd7 in the last iterations
(this was, without having learned the forced mates after Rd7):
83231775 10:18.7 2.77 12t 1.Rac1 Qb4 2.Rd7 Bc6 3.Rxc7 Rac8 4.e7 Bxe7
5.R7xc6 Rxc6 6.Rxc6 Qa3 7.Bxe3 Qxa2 8.Rc7 {260}
297990285 34:49.3 2.77 12. 1.Rac1 Qb4 2.Rd7 Bc6 3.Rxc7 Rac8 4.e7 Bxe7
5.R7xc6 Rxc6 6.Rxc6 Qa3 7.Bxe3 Qxa2 8.Rc7 {260}
426896162 50:29.7 3.17 13++ 1.Rac1 Qb4 2.Rd7 Bc6 3.Rxc7 Rac8 4.Qf7+ Rxf7
5.exf7+ Kf8 6.Rxc8+ Kxf7 7.Rxc6 Be7 8.Bxe3 g5
9.fxg6+ Kf8 {419}
508742187 1:00:24 3.52 13t 1.Rac1 Qb4 2.Rd7 Bc6 3.Rxc7 Rac8 4.Qf7+ Rxf7
5.exf7+ Kf8 6.Rxc8+ Kxf7 7.Rc7+ Be7 8.Bxe3 h5
9.R1xc6 Qg4+ 10.Kg2 Qe2+ 11.Bf2 Qxa2 {259}
-- Dieter
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