Definition:Logical Complement/Complementary Pair

Context
Propositional Logic.

Definition
For any logical formula $$P$$, the set $$\left\{{P, \neg P}\right\}$$ is called a complementary pair of formulas for $$P$$.

$$P$$ and $$\neg P$$ are each the (logical) complement of each other.

$$P$$ can in this context be an atom.