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A very elegantly constructed example of one of the most popular “paradox” themes.
In the Umnov theme, named after Russian composer Evgeny Umnov, a white piece can capture a black piece, but
paradoxically waits until the piece moves away before moving to the vacated square. To be fully thematic the
black piece should then be able to capture the white piece. The key 1.Rb3 threatens
2.Qf7+ Kxc6 3.Qb7. The two thematic variations are 1...Se5 (interfering with the rook guard of
d5) 2.Bc4+ Kxc4 3.Qe6 or 2...Sxc4 3.Rd3, and 1...Sg5 (interfering with the rook guard of
f5) 2.Be4+ Kxe4 3.Qf5 or 2...Sxe4 3.Rd3. There is one by-play variation,
1...Re5 2.Sg6 (threat 3.Sf4) Rf5 3.Se7, while 1...Sb6 leads to a new mate
following the threat 2.Qf7+ Kxc6 3.Bb5.
Dafydd Johnston: It is amazing that although bishop takes either knight is not a threat, on move two White mates by playing the bishop to the squares vacated by those knights. The knight mates after 1...Re5 make a nice contrast to the diagonal activity of the bishop and queen.
Jacob Hoover: This one was TOUGH. In each line White plays to a square only after Black has vacated it, and therein lies the paradox effect. (Also, note that in each line the black defense interferes with the rook, making the alternative sublines possible.) Even though I almost didn't solve this problem, I enjoyed it a lot. I like "weird" problem themes like this one.
Any comments or questions on this problem should be addressed to
Michael McDowell using the ‘Contact’ item in the menu on the left.