- Each of the four men and Esther is a knight or a liar.
- Arthur says: "Exactly one of us four men is a knight."
- Barton says: "Exactly one of us four men is a liar."
- Claude says: "Arthur or Barton is Esther’s fiancé."
- Esther says: "My fiancé and I are either both knights, or both of us are liars."