quinta-feira, 25 de janeiro de 2018

Xadrez - Mate em 25! (Jean-Luc Seret)

Jean-Luc Seret, Themes 64, 1975.
Código FEN: 8/1p6/8/pBP4r/p3R2P/K7/3p1p1p/3k4 w - - 0 1.

As Brancas jogam e dão xeque-mate em 25 lances!

(White to play and give checkmate in 25 moves!)

PCFilho

7 comentários:

  1. This is another problem that needs a hint!

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    Respostas
    1. White needs to keep checking, in order to keep the initiative...

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  2. No, it doesn't. I think I have the basic idea down. It's similar to that mate in 69 Paulo posted recently.

    White would absolutely love to play 1 Kb2? threatening 2 Bxa4 mate, but this plan is derailed by 1 ... a3+! And White can't simply play 1 Bxa4+? either, because after 1 ... Kc1 2 Rc4+ Kb1 3 Bc2+ Ka1! White has nothing. No, White needs to get rid of the b7-pawn first. However, White must also deal with the fact the Black has three pawns that are about to promote. Here's the correct sequence:

    First the b7-pawn is removed:
    1 Bxe2+! Ke1 (not 1 ... Kc1/Kc2? 2 Rc4+ Kb1 3 Bd3+ Ka1 4 Rc2 (threat 5 Ra2 mate) Kb1 5 Rb2++ and 6 Rb1 mate) 2 Bg4+ Kf1 3 Bh3+ Kg1 4 Rg4+ Kh1 5 Bg2+ Kg1 6 Bxb7+ Kf1
    Next, the a4-pawn:
    7 Ba6+ Ke1 8 Re4+ Kd1 9 Be2+ Ke1 10 Bb5+ Kd1 11 Bxa4+ Kc1
    Now the major players go back to the positions they had in the diagram:
    12 Rc4+ Kb1 13 Bc2+ Kc1 (not 13 ... Ka1? 14 Kb3 (threat 15 Ra4 mate) Rxh4 15 Rxh4 any 16 Ra4 mate) 14 Bf5+ Kd1 15 Bg4+ Ke1 16 Re4+ Kf1 17 Bh3+ Kg1 18 Rg4+ Kh1 19 Bg2+ Kg1 20 Bc6+ Kf1 21 Bb5+ Ke1 22 Re4+ Kd1
    The diagram is now restored except without the a4- and b7-pawns. Now the mainplan works:
    23 Kb2! (threat 24 Ba4 mate) Rxc5 24 Ba4+ Rc2 25 Bxc2

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    Respostas
    1. Well done, Jake!!

      I'm glad you solved this one. :)

      (Now I'm a little tired of these long more-movers, and we'll be back with our traditional #2's, #3's and #4's.)

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    2. The mate-in-69 quoted by Jake is THIS PROBLEM, composed by J. C. van Gool and André Chéron. It is the longest direct mate problem ever composed, with the solution meeting the restrictions of only having checks and having no duals.

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  3. As Jake Hoover brilliantly explained, the complete sequence of moves is:

    1. Be2+!! Ke1 2. Bg4+ Kf1 3. Bh3+ Kg1 4. Rg4+ Kh1 5. Bg2+ Kg1 6. Bxb7+ Kf1 7. Ba6+ Ke1 8. Re4+ Kd1 9. Be2+ Ke1 10. Bb5+ Kd1 11. Bxa4+ Kc1 12. Rc4+ Kb1 13. Bc2+ Kc1 14. Bf5+ Kd1 15. Bg4+ Ke1 16. Re4+ Kf1 17. Bh3+ Kg1 18. Rg4+ Kh1 19. Bg2+ Kg1 20. Bc6+ Kf1 21. Bb5+ Ke1 22. Re4+ Kd1 23. Kb2! Rxc5 24. Ba4+ Rc2+ 25. Bxc2#

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    Respostas
    1. Thanks, guys. I really learn a lot from you two.

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