Definition:Infimum of Mapping/Real-Valued Function/Definition 2
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This page is about Infimum of Real-Valued Function. For other uses, see Infimum.
Definition
Let $f: S \to \R$ be a real-valued function.
Let $f$ be bounded below on $S$.
The infimum of $f$ on $S$ is defined as $\ds \inf_{x \mathop \in S} \map f x := k \in \R$ such that:
- $(1): \quad \forall x \in S: k \le \map f x$
- $(2): \quad \forall \epsilon \in \R_{>0}: \exists x \in S: \map f x < k + \epsilon$
Also see
Sources
- 1947: James M. Hyslop: Infinite Series (3rd ed.) ... (previous) ... (next): Chapter $\text I$: Functions and Limits: $\S 3$: Bounds of a Function