# Regular value

From Encyclopedia of Mathematics

2020 Mathematics Subject Classification: *Primary:* 57R [MSN][ZBL]

*of a differentiable function $f: \mathbb R^m \to \mathbb R^n$ with $n\leq m$*. A value $c\in \mathbb R^n$ such that the
differential of $f$ is surjective at every preimage of $c$. The concept can be readily extended to the case when the domain
and the target are smooth manifolds and to various infinite-dimensional settings.

**How to Cite This Entry:**

Regular value.

*Encyclopedia of Mathematics.*URL: http://encyclopediaofmath.org/index.php?title=Regular_value&oldid=32301