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Viewing Version 5 of 'necessary and sufficient'
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Title of object: necessary and sufficient
Canonical Name: NecessaryAndSufficient
Type: Definition

Created on: 2006-07-29 14:09:57
Modified on: 2007-04-27 14:34:23

Creator: Wkbj79
Modifier: Wkbj79
Author: Wkbj79

Classification: msc:03B05
Defines: necessary, necessity, sufficient, sufficiency

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:

The statement ``$p$ is {\sl necessary\/} for $q$'' \PMlinkescapetext{means} ``$q$ \PMlinkname{implies}{Implication} $p$''.

The statement ``$p$ is {\sl sufficient\/} for $q$'' \PMlinkescapetext{means} ``$p$ \PMlinkname{implies}{Implication} $q$''.

The statement ``$p$ is {\sl necessary and sufficent\/} for $q$'' \PMlinkescapetext{means} ``$p$ \PMlinkname{if and only if}{Iff} $q$''.

For an example of how these \PMlinkescapetext{terms} are used in mathematics, see complete ultrametric field.