# Question: let be a well formed formula whose only connective...

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Let α be a well formed formula whose only connective symbols are ∧, ∨, and ¬. Let α∗ be the result of interchanging ∧ and ∨ and replacing each sentence symbol by its negation. Show that α∗ is tautologically equivalent to (¬ α). Use the induction principle.

Remark: It follows that if α |==| β then α∗ |==| β∗.