Showthat $\mathrm p \leftrightarrow \mathrm q$ and $(\mathrm p\wedge \mathrm q) \vee (\neg \mathrm p \wedge \neg \mathrm q)$ are logically equivalent
proving logical equivalence $(P \leftrightarrow Q) \equiv (P \wedge Q) \vee (\neg P \wedge \neg Q)$