Definition:Mapping/Also defined as

Mapping: Also defined as

Some approaches, for example 1999: András Hajnal and Peter Hamburger: Set Theory, define a mapping as a many-to-one relation from $S$ to $T$, and then separately specify its requisite left-total nature by restricting $S$ to the domain.

However, this approach is sufficiently different from the mainstream approach that it will not be used on $\mathsf{Pr} \infty \mathsf{fWiki}$ and limited to this mention.

Sources

• 1999: András Hajnal and Peter Hamburger: Set Theory ... (previous) ... (next): $1$. Notation, Conventions: $10$: Definition $1.3$