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Viewing Version 9 of 'locally free'
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Title of object: locally free
Canonical Name: LocallyFree
Type: Definition

Created on: 2003-08-19 05:51:58
Modified on: 2004-02-19 13:48:42

Creator: mps
Modifier: mps
Author: mps
Author: yark
Author: bwebste

Classification: msc:14A99

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

Revise according to altomani's comment ($\O_X$ -> $(\O_X)_p$).

Preamble:

\usepackage{amssymb}
\usepackage{amsmath}
\usepackage{amsfonts}

\newcommand{\F}{\mathcal{F}}
\renewcommand{\O}{\mathcal{O}}
Content:

\PMlinkescapeword{free}
\PMlinkescapeword{rank}

A sheaf of $\O_X$-modules $\F$ on a ringed space $X$ is called {\em locally free} if for each point $x\in X$, there is an open \PMlinkname{neighborhood}{Neighborhood}
$U$ of $x$ such that $\F|_U$ is \PMlinkname{free}{FreeModule} as an $\O_X|_U$-module, or equivalently, $\F_x$, the stalk of $\F$ at $x$, is free as a $\O_X$-module. If $\F_x$ is of \PMlinkname{finite rank}{ModuleOfFiniteRank} $n$, then $\F$ is said to be of rank $n$.