Definition:Image of Class under Mapping

Definition
Let $V$ be a basic universe

Let $f: V \to V$ be a mapping.

Let $A$ be a class.

The image of $A$ (under $f$) is defined and denoted as:
 * $f \sqbrk A := \set {y: \exists x \in A: \map f x = y}$

That is, $f \sqbrk A$ is the class of all $\map F x$ where $x \in A$.

Also see

 * Definition:Image of Subset under Mapping