Definition:Semantic Equivalence/Predicate Logic/Definition 2

Definition
Let $\mathbf A, \mathbf B$ be WFFs of predicate logic.

Then $\mathbf A$ and $\mathbf B$ are equivalent :


 * $\mathbf A \iff \mathbf B$ is a tautology

where $\iff$ is the biconditional connective.

Also see

 * Definition:Semantic Consequence (Predicate Logic)
 * Definition:Logical Equivalence