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Viewing Version 4 of 'filtration'
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Title of object: filtration
Canonical Name: Filtration
Type: Definition

Created on: 2002-01-05 03:26:49
Modified on: 2005-04-03 23:10:45

Creator: CWoo
Modifier: CWoo
Author: djao

Classification: msc:03E20

Revision comment (for changes between this and next version):

Changes for correction #14443 ('filtration of sigma algebras').

Preamble:

\usepackage{amssymb}
\usepackage{amsmath}
\usepackage{amsfonts}
\usepackage{graphicx}
\usepackage{xypic}
Content:

A {\em filtration} is a sequence of sets $A_1, A_2, \dots, A_n$ with
$$
A_1 \subset A_2 \subset \cdots \subset A_n.
$$
If one considers the sets $A_1, \dots, A_n$ as elements of a larger set which are partially ordered by inclusion, then a filtration is simply a finite chain with respect to this partial ordering. It should be noted that in some contexts the word ``filtration'' may also be employed to describe an infinite chain.