\section{FROM GIS TO COMPLEX GIS}
%\section{FROM GEOGRAPHIC INFORMATION \\ {\bf SYSTEMS (GIS) TO COMPLEX } \\ {\bf GEOGRAPHIC INFORMATION} \\{\bf SYSTEMS (CGIS)}}

A Geographic Information System (GIS) is a computer-based tool using geographical objects. A GIS is composed of a Geographical Data Base (GDB) with applicative operators which allow it to get, to stock, to verify, to manipulate, to analyze and to represent the spatial data of the GDB. \\


The originality of Geographical Data Base from ordinary Data Base is the use of spacial data \cite{rigaux}. the latter may be  represented in a  Geographical Data Base with two aspects: in raster mode or in vector mode. The raster mode is based on a pixels grid representation. The vector mode manipulates geographical features. In the following, we will focus our attention on the vector mode representation where each feature is represented by an object. Each object has a semantic part describing the nature of a feature which it represents and a geometric part describing its shape and its localisation. The position of the objects the ones compared with the others is an important information which is usually represented in the Geographical Data Base.\\ 

So, in Geographical Data Bases, geographical information is often represented with three levels: geometric, semantic and topological. From each level, we can define relations between objects that have to be linked corresponding to the specific level. \\

At the semantic level, a Geographical Data Base is often structured with layers. Layers are generally defined concerning a specific thematic  like road traffic, fluvial tracing, building or vegetation. Generally, objects of a same layer have the same geometric representation and share the same topological properties inside networks. \\

All these structured informations which defines a GIS introduce a great number of static dependences but each layer can be generally understood alone or some parts of each layer can be isolated to better understand the dependence between involved objects. Generally the applicative operators can be computed on each of these parts. In that way, we can consider classical GIS as complicated systems in the terminology proposed by Le Moigne \cite{lemoigne}. We can consider that the Geographical Data Base in association with the previous applicative operators which constitute the GIS is a closed system.\\

Today, the complexity of the world needs to use or to add additional functionalities on GIS. Geographical informations deal also with human-landscape interactions. The simulation of social aspects and of ecological processes seems to be more and more linked to the better understanding of the geographical data and its evolution inside its all social, geopolitic and ecological environment. To integrate these new aspects, we have to manage some complex processes like some energetic fluxes that crosses the standard GIS (see the figure \ref{cgis}). This complex fluxes transform the standard GIS in open systems which confer to them some properties linked to complexity. Self-organization and multi-scale organizations can emerge from these complex processes. The expected evolutions of GIS can be considered as the transition which will transform the standard complicated GIS into complex GIS.\\

\begin{figure}[htb]
\begin{center}
%\rotatebox{-90} 
{\includegraphics[scale=0.45]{cgis.eps}}
\caption{GIS under Complex Processus} 
\label{cgis}
\end{center}
\end{figure}

In the following, we deal with a specific improvement on GIS which concerns its own evolution. As described in the previous section, the constant evolution of the real world induces the need to regularly update the geographical data of GIS. This evolution processus is typically a complex processus that generate some dynamical organizational processes inside GIS. The data themselves retro-act on the processus during the propagation method that we will present in the next sections \cite{kadri1}.  
