Bill Whyatt
Something a little different this week. The white king must first be
placed on the board before the problem is solved as a conventional mate
in two. Which is the correct square for the king?
1.Qd5 almost solves the diagram as it stands, threatening 2.Qxf7 and giving the variations
1...Sg5 2.Qd8 and 1...Rf8 2.Qd7, however there is no mate after 1...O-O. The castling
defence can be eliminated by first placing the white king at a7,, as retroanalysis shows that the black
king must have moved to allow his counterpart access via d7 or d8. By giving a flight at e7 the key prevents
alternative placings of the white king at a8, b8 or c8.
Richard Stein: Having had Raymond Smullyan's retro books, Sherlock Holmes and Arabian Knights, in my
high school days, I was drawn in by this one. My analysis determined that the white king had to be on a7
(so black can't castle, and Ke7 is not discovered check) and that 1.Qd5 is the key. Sort of reminded me of a
haunting problem in Smullyan’s book Sherlock Holmes, where Black mates an invisible White king in one move.