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Exactly one of us is a knight

knights-and-knaveslogiccase-analysis

You meet two islanders, A and B, each a knight (always truthful) or a knave (always lying). A says:

"Exactly one of us two is a knight."

B says nothing.

What can you conclude about A? About B?

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Try both possibilities for A and see what each forces for B. You may find that one of them cannot be determined.

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The theory behind this question.

Cheryl's Birthday and Iterated KnowledgeLogic and QuantifiersOne Question, Two Guards, One DoorProof Techniques: Direct, Contrapositive, ContradictionAdaptive Versus Pre-Committed Weighing Strategies

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