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\textbf{Algebraic structures }
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\textbf{  M. }
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{\bf Abstract.}
 This paper is motivated by the results in [7]. 
2010 MSC: 68Q70\\

Key words: Automaton
\section{Introduction}
 With the advent of electronic computers in the 1950’s, the study of simple formal models of computers such as automata was given a lot of attention.

\begin{proposition}\label{2.7}
 Let $L_1$, $L_2$ .
\begin{itemize}
 \item [(i)] $<L_1, L_2>$ if and only 

 \item[(ii)] If $deg^{-}(L ) \neq 0$ .

 \item[(iii)] If either $L_1$, $L_2$ .
\end{itemize}
\end{proposition}
\begin{proof} 
\begin{itemize}
\item [(i)] Assume that $<L_{1},L_{2}>$. 
\item[(ii)] Let $t_{1}, \cdots, t_{k}$ 
\item[(iii)] Suppose that $L_{1},L_{2}$ are minimal elements 
\end{itemize}
\end{proof}


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\bibitem{ref:1} G. ~Birkhoff, {\em Lattice theory}, Amer. Math. Soc., (1973).



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