\begin{itemize}
 \item \emph{Strategy}: sequence of elements updated at time  $t$;
   \begin{itemize}
   \item $n*n$ diagonal matrix: $J_{ii}^t = 1$ iff $X_i \in E_i$ 
     is updated at time $t$
   \end{itemize}
 \item \emph{Visibility Dates}: sequence of the more recent dates where 
   components know values of other ones  
   \begin{itemize}
   \item $n*n$ matrix  $S_{ij}^t$: highest $t'$ 
     s.t. $t' \le t$ and $X_j^{t'}$ is accessible for $i$
   \item Communcation delays from $j$ to $i$: $t - S_{ij}^t$
   \end{itemize}
 \item \emph{Iterations modes}:
\[
X^{t+1}= (I -J^t)X^t + J^t 
\left(
\begin{array}{c}
F_1
\left( X_1^{S_{11}^t},\ldots, X_{n}^{S_{1{n}}^t} \right) \\
\vdots \\
F_{n} \left( X_1^{S_{{n}1}^t},\ldots, X_{n}^{S_{{n}{n}}^t} \right) 
\end{array}
\right)
\]
\begin{itemize}
\item Parallel mode: $J^t=I$ and $S^t=(t)$
\item Chaotic mode: $S^t=(t)$
\item Asynchronous: no constraint
\end{itemize}
\end{itemize}