Definition:Preimage/Mapping/Mapping

Definition
Let $f: S \to T$ be a mapping.

The preimage of $f$ is defined as:


 * $\Preimg f := \set {s \in S: \exists t \in T: f \paren s = t}$

That is:
 * $\Preimg f := f^{-1} \sqbrk T$

where $f^{-1} \sqbrk T$ is the image of $T$ under $f^{-1}$.

In this context, $f^{-1} \subseteq T \times S$ is the the inverse of $f$.

It is a relation but not necessarily itself a mapping.

Also known as
Consistently with the definition as the image of $T$ under $f$, $f^{-1} \sqbrk T$ can also be used instead of $\Preimg f$.

Also see

 * Definition:Image of Mapping
 * Definition:Domain of Mapping
 * Definition:Codomain of Mapping
 * Definition:Range of Mapping

Generalizations

 * Definition:Preimage of Relation