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Subject: Re: Mate in12

Author: Dieter Buerssner

Date: 16:22:31 03/14/04

Go up one level in this thread


On March 14, 2004 at 15:08:12, Steven Edwards wrote:

>On March 14, 2004 at 14:28:36, John Merlino wrote:
>
>>On March 14, 2004 at 13:13:18, Art Basham wrote:
>>
>>>7B/6N1/8/5B2/8/K7/pr6/k7 w - - 0 1
>How about mate in 26:
>
>1. Ka4 Rh2 2. Nh5+ Rb2 3. Nf6 Rb8 4. Bg7 Ra8+ 5. Kb3 Ra3+ 6. Kc2 Rc3+ 7. Kd2
>Kb2 8. Nd5 a1=Q 9. Bxc3+ Ka2 10. Nb4+ Kb3 11. Be6+ Ka4 12. Bxa1 Kxb4 13. Bd4
>Kb5 14. Bd5 Kb4 15. Bb7 Ka5 16. Ba7 Ka4 17. Ba6 Ka5 18. Bd3 Ka4 19. Bc5 Ka5 20.
>Kc3 Ka4 21. Bb6 Ka3 22. Bb5 Ka2 23. Kc2 Ka1 24. Ba4 Ka2 25. Bb3+ Ka1 26. Bd4#

Do you find a mate in (at most) the 26th move, too after 3...Rh2 instead of Rb8?

With the help of a little backwards analysis, I get the following in Yace:

After 3...Rb8:

 14.22	 0:00 	  +M23 	4.Bg7 Ra8+ 5.Kb3 Ra3+ 6.Kc2 Rc3+ 7.Kd2 Kb2 8.Nd5 (308)
23.6

(Mate at move 26)

After 3...Rh2:

 15.01	 0:00 	  +M26 	4.Bg7 Rc2 5.Nd7+ Kb1 6.Kb3 a1N+ 7.Bxa1 Kxa1 8.Kxc2 Ka2
(664) 110.6
(Mate at move 29)

Going further back to the root:

 15.01	 0:00 	  +M29 	1.Ka4 Rh2 2.Nh5+ Rb2 3.Nf6 Rh2 4.Bg7 Rc2 5.Nd7+ Kb1 6.Kb3
a1N+ 7.Bxa1 Kxa1 8.Kxc2 Ka2 (211) 4.7

which can be considered as a proof, that white has a forced mate in 29 or faster
(or as a proof of a bug in my engine ...).

Regards,
Dieter



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