Problem
The Problem
Three friends — Alice, Bob, Carol — play a card game. Each draws one card from a standard 52-card deck and holds it to their forehead (so they can see the others' cards but not their own).
They simultaneously say either "I know my card" or "I don't know". The rounds continue until someone knows.
Cards are distinct; everyone is perfectly logical; everyone knows everyone else is logical.
After round 1, no one knows. After round 2, no one knows. After round 3, all three know. What cards do they hold?