Riddle of the Week #5: A Life-or-Death Question About Hats
Riddle: '4 prisoners wearing black and white hats' – answer explained!
Four prisoners wearing black and white hats - Puzzling Stack Exchange
Induction puzzles - Wikipedia
Who Will Shout First? 4 Criminals Are Caught and Are to Be Punished the Judge Allows Them to Be Freed if They Can Solve a Puzzle if They Do Not They Will