<Li> (p ⟹ q) ∨ (p ⟹ r) ≡ p ⟹ (q ∨ r) (\ displaystyle (p \ implies q) \ vee (p \ implies r) \ equiv p \ implies (q \ vee r)) </Li> <Li> (p ⟹ r) ∧ (q ⟹ r) ≡ (p ∨ q) ⟹ r (\ displaystyle (p \ implies r) \ wedge (q \ implies r) \ equiv (p \ vee q) \ implies r) </Li> <Li> (p ⟹ r) ∨ (q ⟹ r) ≡ (p ∧ q) ⟹ r (\ displaystyle (p \ implies r) \ vee (q \ implies r) \ equiv (p \ wedge q) \ implies r) </Li> <P> Logical equivalences involving biconditionals: </P>

When do we say that two fol formulas are logically equivalent