Monotone convergence, Fatou, and dominated convergence

Theorem taught in Expectation and convergence, part of Stochastic processes

Monotone convergence, Fatou, and dominated convergence

Type Theorem
Taught in Expectation and convergence
Part Stochastic processes

If 0\le X_n\uparrow X with probability 1, the monotone convergence theorem gives \mathbb{E} X_n\uparrow\mathbb{E} X, and the limit may be infinite. If X_n\ge 0, Fatou’s lemma gives \mathbb{E}(\liminf_n X_n)\le\liminf_n\mathbb{E} X_n. If X_n\to X with probability 1 and |X_n|\le Y for every n, with \mathbb{E} Y<\infty, the dominated convergence theorem gives \mathbb{E} X_n\to\mathbb{E} X.

Used in

See also

Modes of convergence · Strong law · Uniform integrability

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