[Retros] non-FEN fun

Noam Elkies elkies at math.harvard.edu
Mon Aug 19 13:10:09 EDT 2013

As it happens Chessbase.com just ran this article


on its first "Christmas puzzle" ever, which asked in 1999 for
a legal came starting 1 e4 and ending 5...NxR#. [What's the
source for this puzzle? I don't think it's given in the
Chessbase article but surely somebody on this mailing list knows it.]
This is very hard for most human players, even though the solution
is not quite unique. But it's not the only such puzzle. Another,
which *does* have a unique solution, starts with 1 a3 and ends
on move 5 with White giving mate with a Rook. I don't know
the composer/discoverer of this either, but I first saw it
decades ago in a column by Pal Benko. Are there other such examples
known, or discoverable by computer now that F.Labelle is active again
(welcome back!)? There's of course 1 h4 ... 6 PxB=N#, which is unique
even without specifying the first move; and Labelle found a few more
such examples (all shorter) determined completely by their last move.
But I figure that specifying both first and last move should allow for
a greater and hopefully even more interesting selection of puzzles.


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