PlanetMath (more info)
 Math for the people, by the people. Sponsor PlanetMath
Encyclopedia | Requests | Forums | Docs | Wiki | Random | RSS  
Login
create new user
name:
pass:
forget your password?
Main Menu
Viewing Version 2 of '$C^*$-algebra homomorphisms have closed images'
[ view '$C^*$-algebra homomorphisms have closed images' | back to history ]

Title of object: $C^*$-algebra homomorphisms have closed images
Canonical Name: CAlgebraHomomorphismsHaveClosedImages
Type: Theorem

Created on: 2008-01-14 20:19:19
Modified on: 2008-01-14 20:21:43

Creator: asteroid
Modifier: pahio
Author: asteroid

Classification: msc:46L05
Synonyms: $C^*$-algebra homomorphisms have closed images=image of $C^*$-homomorphism is a $C^*$-algebra

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

Two A's changed to \mathcal{A}

Preamble:

% this is the default PlanetMath preamble. as your knowledge
% of TeX increases, you will probably want to edit this, but
% it should be fine as is for beginners.

% almost certainly you want these
\usepackage{amssymb}
\usepackage{amsmath}
\usepackage{amsfonts}

% used for TeXing text within eps files
%\usepackage{psfrag}
% need this for including graphics (\includegraphics)
%\usepackage{graphicx}
% for neatly defining theorems and propositions
%\usepackage{amsthm}
% making logically defined graphics
%\usepackage{xypic}

% there are many more packages, add them here as you need them

% define commands here
Content:

\PMlinkescapeword{image}
\PMlinkescapeword{closed}

{\bf Theorem -} Let $f: \mathcal{A} \longrightarrow \mathcal{B}$ be a *-homomorphism between the \PMlinkname{$C^*$-algebras}{CAlgebra} $\mathcal{A}$ and $\mathcal{B}$. Then $f$ has \PMlinkname{closed}{ClosedSet} \PMlinkname{image}{Function}, i.e. $f(A)$ is closed in $\mathcal{B}$.

Thus, the image $f(A)$ is a $C^*$-subalgebra of $\mathcal{B}$.