Retrograde Chess Problems

Retrograde chess problems are logic puzzles which involve trying to figure out what happened previously in a chess game, based only on the actual rules of chess. See for example The Retrograde Analysis Corner, a chess.com discussion, a mathpuzzle.com page, and the amazing book The Chess Mysteries of Sherlock Holmes by Raymond Smullyan.

My wonderful nephew Aaron Trainor has written two very clever retrograde chess problems (the second is actually three problems in one):

1. Sherlock Holmes and the Curious Case of the Chess Bomb (see also the problem with solution).
2. Sherlock Holmes and the Simultaneous Monochromatic Chess Exhibition (see also the problem with solution).

Give them a try!

-- Jeffrey Rosenthal