Formula Logical Equivalence

For Formulas ${\mathcal{F}}_1,{\mathcal{F}}_2$ ${\mathcal{F}}_1\text{ LEQV }{\mathcal{F}}_2⟺{\mathcal{F}}_1={\mathcal{F}}_2⟺$ ${\mathcal{F}}_1$ Logically Implies ${\mathcal{F}}_2$ and ${\mathcal{F}}_2$ Logically Implies ${\mathcal{F}}_1$