Scenario
A countably infinite number of prisoners, indexed 1,2,3,…, are lined up in single file facing forward.
Each prisoner wears a hat colored either Black (0) or White (1).
Each prisoner k can see all the hats worn by prisoners in front of them (k+1,k+2,k+3,…), but cannot see their own hat or any hat behind them (1,…,k−1).
No communication or sound is permitted once hats are placed. All prisoners must simultaneously guess the color of their own hat.
Your Task
- Define the tail equivalence relation ∼ on the Cantor space of binary sequences S={0,1}N.
- Invoke the Axiom of Choice to construct a collective strategy.
- Prove that this strategy guarantees that at most a finite number of prisoners guess incorrectly, meaning an infinite co-finite tail of prisoners guess correctly.
Constraints
- Hats are chosen arbitrarily from {0,1}N.
- Guesses are strictly simultaneous with no communication.
Examples
If the sequence is 1,0,1,0,0,0,… and the chosen representative is identical except at positions 1 and 3, exactly 2 prisoners guess wrong, and infinitely many prisoners guess correctly.