[Retros] Shortest checkmates in shortest proof games

Noam Elkies elkies at math.harvard.edu
Fri Oct 4 10:59:10 EDT 2002

A.J. Mestel <A.J.Mestel at damtp.cam.ac.uk> writes:

> Is f4 really mate? You get up early! Jonathan

Actually I stayed up too late... Jonathan's right, of course;
Popeye 3.41 confirms 1 e3 e6 2 Qg4 Ke7 3 Be2 Kf6 4 Q:e6+ Kg5 5 f4+
yields a sound PG4.5, but does not mark the final move of a solution
with + or #, so it did no cure me of this hallucination. Fortunately
there's another 4.5-mover: 1 e4 f5 2 Qf3 Kf7 3 Bc4+ Kf6 4 Qc6+ Ke5 5 f4#
(C+ .01s).

I wrote:

> Rosler's 6 g:f8=N# game is famously believed to be the unique game

> that ends with that move; it might also be the unique shortest

> h2 -> N# game.

Um, this should say something like "the unique shortest unique h2 -> N#"
because there are many variations of 1 h4 f6 2 h5 Kf7 3 h6 e6 4 hg Qe8
5 R:h7 and 6 g:h8=N##.


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