Definition:Progressing Mapping

Definition
Let $C$ be a class.

Let $f: C \to C$ be a mapping from $C$ to $C$.

Then $f$ is inflationary :


 * $\forall x \in \Dom f: x \in C \implies x \subseteq \map f x$

That is, for each $x \in C$ in the domain of $C$, $x$ is a subset of $\map f x$.