I have to show that $\models (P \wedge Q) \iff \neg ( \neg P \vee \neg Q )$ is a valid argument.
However, I have no idea how to interpret a $\models$ symbol WITHOUT a LHS. I have always seen it like this $P, P \implies Q \models Q$, which I read as: given the premises on the LHS hold, then RHS is logically entailed. Which I would then just rephrase as a formula like $P \wedge (P \implies Q) \implies Q$, and then use a truth table to show it is true for all $P,Q$.
Now, my intuition is, since there is nothing in the LHS, then RHS is just entailed for everything. And so the formula will be $⊤ \implies [ \ (P \wedge Q) \iff \neg ( \neg P \vee \neg Q ) \ ]$ which, simplifies back to $(P \wedge Q) \iff \neg ( \neg P \vee \neg Q )$ (using disjunction elimination and so on) and now I can make a truth table for this.
Is my approach correct? Or did I get completely lost.