# 外测度　`def.outer-measure`
外测度（Outer Measure）
layer 14 · 定义 · 测度的构造 · 分析学
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设 $X$ 是非空集合。函数 $\mu^* : \mathcal{P}(X) \to [0, +\infty]$ 是一个**外测度**，当且仅当
> 陈述续见 [nodes/def.outer-measure.2.md](./def.outer-measure.2.md)


## 为什么成立（入边，证明在 proofs/）
- …另有入边，续页见 [nodes/def.outer-measure.4.md](./def.outer-measure.4.md)

## 它能推出什么 / 谁在用它
- …另有出边，续页见 [nodes/def.outer-measure.5.md](./def.outer-measure.5.md)

## English abstract · **draft** · machine-drafted, pending author review; Chinese is authoritative
> English abstract 续见 [nodes/def.outer-measure.3.md](./def.outer-measure.3.md)

refs: Halmos, Measure Theory, §11；Folland, Real Analysis, §1.4

外部：Wikipedia https://en.wikipedia.org/wiki/Outer_measure · nLab https://ncatlab.org/nlab/show/outer+measure

> 说明见 `notes/def.outer-measure.md`

引用：`def.outer-measure`（内容 v0.9.0）· 条款见 [LICENSE.txt](../LICENSE.txt)