What is the missing piece (marked "?") in this configuration of a normal chess game?

BLACK

WHITE
Notice that the Black King is in check by the White Rook.

(In reply to re(2): An impossible check?? (partial spoiler) by brianjn)

"Additionally, as for "Very good observation, brianjn", I cannot take fully credit for that.  pcbouhid originally had this as a text diagram, I offered to build it as a picture but in doing so I made a noticeable error which, when drawn to my attention, I rectified.  Later I saw that "glaring mistake" asked pcbouhid to reassure me that the picture was indeed correct.  His reply was to "focus on the other Rook".

It took quite some time before I realised that the discovered check was due to the promotion of a pawn; well, that "very good observation" was somewhat assisted.  With that in mind I felt I couldn't give too much away - "inside information" so to speak."

All that I can say is that you are very correct, Brian.

And, IMHO Raymond Smullyan, which composed this little masterpiece in 1925, at age of 16, deserves a "5+" for it.

Posted by pcbouhid on 2008-06-12 21:51:07