00A06-PlusSign.tex

\documentclass[12pt]{article}
\usepackage{pmmeta}
\pmcanonicalname{PlusSign}
\pmcreated{2013-03-22 17:35:43}
\pmmodified{2013-03-22 17:35:43}
\pmowner{pahio}{2872}
\pmmodifier{pahio}{2872}
\pmtitle{plus sign}
\pmrecord{5}{40009}
\pmprivacy{1}
\pmauthor{pahio}{2872}
\pmtype{Definition}
\pmcomment{trigger rebuild}
\pmclassification{msc}{00A06}
\pmclassification{msc}{00A05}
\pmsynonym{plus}{PlusSign}
\pmrelated{Sum}
\pmrelated{SumOfSeries}
\pmrelated{SignumFunction}
\pmrelated{OppositeNumber}
\pmrelated{ProductOfNegativeNumbers}

\endmetadata

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\begin{document}
There are two main uses of the {\em plus sign} ``$+$'' (which is a simplified form of ``\&'') in the mathematics and the applying sciences:
\begin{itemize}
\item The original use is as the sign for the binary operation {\em addition} of numbers and other elements of rings and algebras, vectors, etc.:
$$a\!+\!b\; := \mbox{\, the sum of\, } a \mbox{\, and\, }b$$
\item There is also a special use for the unary operation {\em identity mapping} concerning numbers and other ring elements:
$$+a\; :=\; a \mbox{\; (for all  } a)$$
\end{itemize}
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\end{document}