\documentclass[11pt]{article}
\usepackage{amsfonts}
\usepackage[greek]{babel}
\usepackage[iso-8859-7]{inputenc}
\usepackage{shapepar}

\newcommand{\first}{\begin{minipage}{195.8pt}%
\latintext\begin{enumerate}
\item Who is Ast\'erix?
\item Who is Ast\'erix's best friend?
\item Has Ast\'erix been in
        \begin{enumerate}
        \item Greece?
        \item Australia?
        \end{enumerate}
\item What is Ast\'erix's nationality?
\item to who belongs Id\'efix?
\end{enumerate}
\end{minipage}
}

\newcommand{\second}{\begin{minipage}{200pt}%
\latintext\begin{itemize}
\item This is first
\item This is second
\end{itemize}
\end{minipage}}

\newcommand{\third}{\begin{minipage}{200pt}%
\latintext\begin{itemize}
\item[$\mathbb N$] The natural numbers
\item[$\mathbb Z$] The integer numbers
\item[$\mathbb R$] The real numbers
\item[$\mathbb C$] The complex numbers
\end{itemize}
\end{minipage}}

\newcommand{\fourth}{\begin{minipage}{200pt}%
\latintext\begin{description}
\item[Perl] A programming Language
\item[\TeX] A typesetting system
\item[CWEB] A litterate programming tool
\end{description}
\end{minipage}}

\begin{document}


$\left.\hbox{\first}\right\}\ \hbox{\textlatin{\Large enumerate}}$


\bigskip

$\left.\hbox{\second}\right\}\ \hbox{\textlatin{\Large itemize}}$

\bigskip

$\left.\hbox{\third}\right\}\ \parbox{\Large \begin{minipage}{90pt}%
                                                \textlatin{itemize}
                                                 ìå áëëáãìÝíá \textlatin{items.}
                                                \end{minipage}}$

\bigskip

$\left.\hbox{\fourth}\right\}\ \hbox{\textlatin{\Large description}}$

\vspace*{1.5cm}


\centerline{\large Ìç áíáëõôéêÜ ïñéæüìåíåò óõíáñôÞóåéò}
\latintext
$$|x| = \left\{
        \begin{array}{ll}
        x, & \mathrm{if}\; x\geq 0\\
        -x, & \mathrm{otherwise.}
        \end{array}
\right.
$$
\greektext

\newpage
\heartpar{\footnotesize%
Ðéóôåýù üôé ôá ðïëõÜñéèìá êáé ÷áñáêôçñéóôéêÜ ðáñáäåßãìáôá ðïõ óõíïäåýïõí êÜèå íÝá
åíôïëÞ Þ åíüôçôá èá äþóïõí ôçí åõêáéñßá áêüìç êáé óôïõò ìç åéäéêïýò, äçëáäÞ óôïõò ìç
ãíþóôåò ôçò åðéóôÞìçò ôçò ðëçñïöïñéêÞò, áëëÜ êáé óå üëïõò ôïõò åñåõíçôÝò êáé ðáíåðéóôçìéáêïýò
íá áöïìïéþóïõí ãñÞñïñá êáé åýêïëá ôéò ðïëõÜñéèìåò äõíáôüôçôåò êáé åõêïëßåò ôïõ
ðåñéâÜëëïíôïò åñãáóßáò ôïõ \LaTeX\ êáé íá êáôáóôïýí ôÜ÷éóôá éêáíïß íá áðïäþóïõí êáé íá
äçìéïõñãÞóïõí Ýíôõðá-êåßìåíá ðïõ ðñéí ëßãá ÷ñüíéá Þôáí ðñïíüìéï éó÷õñþí êáé ðáíÜêñéâùí
ëéíïôõðéêþí ìç÷áíþí}

\begin{equation}
\nabla^2 =\frac{\partial^2}{\partial x^2} +
                \frac{\partial^2}{\partial y^2} +
                \frac{\partial^2}{\partial z^2} 
\end{equation}

\begin{eqnarray}
\nabla^2 &=&\frac{\partial^2}{\partial x^2} +
                \frac{\partial^2}{\partial y^2} +
                \frac{\partial^2}{\partial z^2} \\
&=&\frac{\partial^2}{\partial x^2} +
                \frac{\partial^2}{\partial y^2} +
                \frac{\partial^2}{\partial z^2} \\
&=&\frac{\partial^2}{\partial x^2} +
                \frac{\partial^2}{\partial y^2} +
                \frac{\partial^2}{\partial z^2} 
\end{eqnarray}

\bigskip

\centerline{\Large\bfseries ÁóêÞóåéò}
\begin{eqnarray}
\biggm|\Bigl( Kf, F\Bigr)\biggm| &=& \biggm|\Bigl( K-K_n\Bigr)f, f\biggm|\\
&\leq& \biggm\Vert \Bigl(K-K_n \Bigr) f\biggm\Vert\; \Vert f\Vert\\
&\leq& \Vert K-K_n \Vert\\
&\leq& \frac1{n}
\end{eqnarray}

\newpage

\begin{eqnarray}
a &=& \frac12 b\nonumber\\
b &=& \frac{\sin 3}{\cos 4} z + y\\
c &=& \frac12 b+c\nonumber
\end{eqnarray}

\begin{equation}
\delta_{ij} =\left\{ 
\begin{array}{ll}
0, & k\neq i\\
1, & k=i
\end{array}\right.
\end{equation}

\medskip

{\itshape \large Êáé ìßá ãéá áðáéôçôéêÝò/ïýò:}

\latintext
\begin{equation}
f(z)=\left\{
\begin{array}{ll}
\left. \begin{array}{rl}
\hspace*{-0.5cm}z, & z\leq 0 \\
\hspace*{-0.5cm}-z, & z\geq 0
        \end{array}\right\} & \textrm{if $z$ is real number}\\
z^2 +1 & \textrm{if $z$ is in $\mathbb C\setminus\mathbb R$}
\end{array}\right.
\end{equation}



\end{document}