[Retros] [tros] chess puzzle

[Andrej Jakobcic]

2008/3/15, Noam Elkies <elkies at math.harvard.edu>:

> "Frank Tuyl" <tuyl at tpg.com.au> writes:

>

>  > I happened to come across a chess puzzle, published in a Dutch newspaper

>  > a couple of years ago, and after many hours I have not been able to crack it.

>  > After some googling I found your site and was just wondering whether this

>  > would be a way to get the solution from someone. (white to play and win)

>

>  > White: Ka6, Qh2, Nb4, a7

>  > Black: Ka8, Qg6, Nf8, d6

>

>

> Doesn't seem to be a retroanalytic puzzle, which is what this mailing list

>  is for.  Anyway, material is even, Black's King has no moves, and the board

>  is wide open but for now both Queens are out of play, with neither side

>  having a safe check except for Black's threat to free his King with ...d5+.

>  This will also answer the otherwise desirable check 1 Qh1+.  So White

>  would like to play Nd5, blocking that check and threatening mate in one from

>  either b6 or c7 -- but 1 Nd5 lets Black play another check, 1...Qd3+, and then

>  after 2 Kb6 Qxd5 only Black can win.  But if Black didn't have this check

>  then Nd5 would win outright, even without using White's Queen.  So it's

>  worth the Queen to make it possible...

>

>   1 Qh6!! Qxh6 2 Nd5 and 3 Nb6# or 3 Nc7#

>

>  Black can defend either b6 or c7 with either Queen or Knight (Qe3 or g7/h7,

>  Nd7 or e6) but can't stop both mates.  Black doesn't have to play Qxh6, but

>  White is also threatening 2 Qxf8+ and mate, and Black can't hold everything:

>  1...N-any 2 Qxg6; 1...d5+ 2 Qxg6 Nxg6 3 Nd5 and mate; 1...Qf5(f7,g8/e8?)

>  2 Qh1+ (this is good now that the forced reply ...d5 is no longer

>  a cross-check) d5 3 Qxd5+ Qxd5 4 Nxd5 and again mate.  If 1...Qe8? then

>  2 Qh1+ mates on the diagonal, and if 1...qg8 then 2 Nd5 is a faster win.

>

>  Any idea who is the composer and when/where this study was first published?

>

>  --Noam D. Elkies



But what after 1. ... Qe4 ?

--Andrej J.