Definition:Lower Level Set

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Definition

Let $f: S \to \overline \R$ be an extended real-valued function.

Let $\alpha \in \R$.


The $\alpha$-lower level set of $f$ is the set:

$\ds \operatorname {lev} \limits_{\mathop \le \alpha} f := \set {x \in S: \map f x \le \alpha}$


Also see


Sources