‘Moriarty Problem M2’ on page 146 of The Chess Mysteries of Sherlock Holmes by Raymond Smullyan: ambiguous wording of the problem allows for an alternate solution.
The problem as stated: “Neither the White King or Queen has moved during the last 5 moves, nor has any piece been captured during that time. What was the last move?” allows for the very simple solution that comes from the following previous state of the board:
We can see that moving the black pawn up three times and the white bishop twice (5 moves without making a capture or moving the white king or queen), the last move being the Black Pawn from a5 to a4. Smullyan’s intended (and much more interesting solution) comes from this previous state of the board:
The white pawn moves to d6 discovering check, the black king moves into the corner at h8, followed by the white pawn moving to d7, the black pawn moving to a6, the white pawn promoting to a bishop on d8, then Pa5; Bg5, Pa4 and then the last move: the white bishop from g5 to h6. This is actually a total of 9 moves in which there is no capture nor has the white king or queen moved.
The problem, therefore, can be reworded to say :
“Neither the White King or Queen has moved during the last 9 moves, nor has any piece been captured during that time. What was the last move?”
OR
“Neither the White King or Queen has moved during the White’s last 5 moves, nor has any piece been captured during that time. What was the last move?”
allowing for Smullyan’s to be the exclusive solution.