- #1

- 29

- 0

## Main Question or Discussion Point

Be [itex]\alpha[/itex] and [itex]\beta[/itex] two formulas of the propositional calculus, show that [itex]\alpha[/itex] and [itex]\beta[/itex] are logically equivalent if and only if ~[itex]\alpha[/itex] and ~[itex]\beta[/itex] are logically equivalent.