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\noindent\parbox{2.85cm}{\includegraphics*[keepaspectratio=true,scale=1.75]{BJMA.jpg}}
\noindent\parbox{4.85in}{\hspace{0.1mm}\\[1.5cm]\noindent
Banach J. Math. Anal. 2 (2008), no. 1, 40--47\\
$\frac{\rule{4.55in}{0.05in}}{{}}$\\
{\footnotesize
\textcolor[rgb]{0.65,0.00,0.95}{\textsc{\textbf{\large{B}}anach
\textbf{\large{J}}ournal of \textbf{\large{M}}athematical
\textbf{\large{A}}nalysis}}\\
ISSN: 1735-8787 (electronic)\\
\textcolor[rgb]{0.00,0.00,0.84}{\textbf{http://www.math-analysis.org }}\\
$\frac{{}}{\rule{4.55in}{0.05in}}$}\\[.5in]}


\title[Products of Closed Operators]{On Different Products of Closed Operators}

\author[B. Messirdi, M.H. Mortad]{BEKKAI MESSIRDI$^1$ and MOHAMMED HICHEM MORTAD$^2$ $^{*}$}

\address{$^{1}$ D\'{e}partement de Math\'{e}matiques, Universit\'{e} d'Oran
(Es-senia), B.P. 1524, El Menouar, Oran 31000, Algeria.}

\email{\textcolor[rgb]{0.00,0.00,0.84}{bmessirdi@univ-oran.dz,
bmessirdi@yahoo.fr.}}

\address{$^{2}$ D\'{e}partement de Math\'{e}matiques, Universit\'{e} d'Oran
(Es-senia), B.P. 1524, El Menouar, Oran 31000, Algeria.}
\email{\textcolor[rgb]{0.00,0.00,0.84}{mortad{\_}maths@yahoo.com,
mortad@univ-oran.dz.}}

\dedicatory{{\rm  Submitted by H. Dedania}}


\subjclass[2000]{47A05.}

\keywords{Closed operator, product, Hilbert space.}


\date{Received: 26 December 2007; Accepted: 9 April 2008.
\newline \indent $^{*}$ Corresponding author}


\begin{abstract}
The purpose of this work is to give different products of closed
operators together with their faults and assets.
\end{abstract}
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