[Retros] Challenge

[andrew buchanan]

Hi Chaps,



> I think that this example has many flaws


http://www.k4it.de/index.php?topic=egtb&lang=en provides Web Query for Nalimov Endgame Tablebases and reveals that any non-suicidal knight move is also a win, for sufficiently high n.


> but I agree with the conclusion, that it should be easy to build a position as intended by Kevin


I offer N7/1p6/kP6/Pp6/1P6/8/8/Kb6, which has 9 units.


> If the keys must all be unique, the challenge is, of course, much tougher.


A looser constraint which achieves the same desired effect to avoid infinity is simply to demand that there must exist a maximum n for which there exists a mate in exactly n.

All the best,
Andy.


----- Original Message ----
From: Pascal Wassong <pascal.wassong at free.fr>
To: The Retrograde Analysis Mailing List <retros at janko.at>
Sent: Sat, November 28, 2009 8:59:15 PM
Subject: Re: [Retros] Challenge

Hello,

I think that this example has many flaws, but I agree with the
conclusion, that it should be easy to build a position as intended by
Kevin.

In the given example:
- for n > 2, white can play 1.B~ and 2.Bf8 etc...
- for n > 8 and n < 52, white can play 1.h7, and the wKh6 can help to
  mate.
- but for n > 51, it is better for white to keep a pawn move for
  later, so that the 50 moves rules doesn't force a draw.
- for n > 100, I don't know if there are solutions, as the bK must
  move to allow for 2 pawn moves or a pawn move and a capture.

Pascal





>>>>> "Kevin" == Kevin Begley <kevinjbegley at gmail.com> writes:


    Kevin> Hi all, Unless I have misread Juha Saukkola's challenge, it
    Kevin> is rather trivial to achieve n=infinity with only 6 men...

    >> Find a such kind of position that there is mate in 1 with only
    >> one move, mate in 2 with only one starting move, ...  mate in n
    >> with only one starting move.  maximize n!

    Kevin> Nowhere does it say that the key for each mate (from #2 to
    Kevin> #n) must be unique, so why not:

    Kevin> white Ka1 Bf8 Sf6 Ph6 black Kh8 Ba2 (4+2)

    Kevin> #1 Bg7# #2 (exact): 1.Kb2!  ...  #n (exact): 1.Kb2!  (for
    Kevin> all n > 2).

    Kevin> If the keys must all be unique, the challenge is, of
    Kevin> course, much tougher.

    Kevin>  Best, Kevin.
    Kevin> _______________________________________________ Retros
    Kevin> mailing list Retros at janko.at
    Kevin> http://www.pairlist.net/mailman/listinfo/retros

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