Resumen de S5 solution to the red hat puzzle

Robert C. Robinson

• I argue that the solution to the Red Hat Problem, a puzzle derived from interactive epistemic logic, requires S5. Interactive epistemic logic is set out in formal terms, and an attempt to solve the red hat puzzle is made in Kôó, Kñô, and Kñó, each of which fails, showing that a stronger system, Kôóñ is required.