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exhaustion by compact sets (Theorem)

Let $U$ be an open set in $ \mathbbmss{R}^n$ (or a manifold with countable base). Then there exists a sequence of compact sets $K_1, K_2, \ldots$ such that \begin{eqnarray*} K_i &\subseteq& \operatorname{int} K_{i+1}, \quad i=1,2,\ldots, \\ U &=& \cup_{i=1}^\infty K_i, \end{eqnarray*}where ``$\operatorname{int}$ '' denotes the topological interior. Such a sequence is called an exhaustion by compact sets for $U$ .




"exhaustion by compact sets" is owned by matte. [ full author list (2) ]
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See Also: method of exhaustion


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proof of exhaustion by compact sets for $\mathbb{R}^n$ (Proof) by cvalente
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Cross-references: interior, compact sets, sequence, base, countable, manifold, open set

This is version 3 of exhaustion by compact sets, born on 2005-05-22, modified 2005-05-22.
Object id is 7103, canonical name is ExhaustionByCompactSets.
Accessed 1780 times total.

Classification:
AMS MSC53-00 (Differential geometry :: General reference works )

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