Puzzles that focus on getting information from truth-tellers (who never lie), liars (who always lie), and Jokers (who answer at random).
This type of puzzle focuses on getting information by asking questions to members of 2 or 3 of the following groups:
- Truth-tellers (or Knights), who always tell the truth.
- Liars (or Knaves), who always lie.
- Jokers, who answer at random.
The questioner doesn't know who they're asking — Knight, Knave or Joker — and often only yes/no-questions (or similarly restricted questions) are allowed. Restrictions on the number of questions asked are also common for these questions.