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    Monotonicity and countable subadditivity of measures

    T-7LQ7X

    Measures grow with inclusion and never exceed the sum of a countable cover.Suggest a slogan

    Let \((X, \mcm, \mu)\) be a measure space.

    1. (Monotonicity) If \(E,F\in\mcm\) and \(E \subseteq F\), then \(\mu(E) \leq \mu(F)\).

    2. (Countable subadditivity) If \(E_k\in\mcm\) for \(k\geq1\), then \[ \mu\qty{\bigcup_{k\geq 1} E_k} \leq \sum_{k\geq 1} \mu(E_k). \]