Spies and Double Agents

Two logical spies, M and N, sent reports to Z, the head of the CIA. Z suspected one to be a double agent. The task is to find which spy is trustworthy and always tells the truth, which spy is untrustworthy and always lies, and to evaluate their statements, , , , …, for their truth values. The contents of the statements are classified. For negation, conjunction, disjunction, implication, and equivalence, they used the symbols , , , , . For readability, F (for False) is left blank in the truth tables.


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The idea for the Demonstration comes from [1].
[1] D. Shasha, The Puzzling Adventures of Dr. Ecco, New York: W. H. Freeman, 1988 p. 41.
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