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, Dans un premier temps, une question préliminaire est traitée: puisque les noeuds au sein d'une partie ne sont pas nécessairement connexes, comment quantifier l'impact d'une contrainte de connexité ? Nous proposons ensuite un algorithme de partitionnement assurant que le réseau réduit soit scale-free. Ceci permet de tirer profit des propriétés intrinsèques de ce type de réseaux. Nous nous intéressons également aux propriétés à préserver pour respecter la nature physique et dynamique du réseau initial. Dans une troisième partie, nous proposons une méthode pour identifier les noeuds à mesurer dans un réseau pour garantir une reconstruction efficace de la valeur moyenne des autre noeuds. Finalement, nous proposons trois applications: la première concerne le trafic routier et nous montrons que notre premier algorithme de partitionnement permet d'obtenir un réseau réduit émulant efficacement le réseau initial. Les deux autres applications concernent les réseaux d'épidémiologie. Dans la première nous montrons qu'un réseau réduit scale-free permet de construire une stratégie efficace d'attribution de soin au sein d'une population, l'élaboration d'algorithmes de partitionnement et diverses problématiques connexes sont traitées au long de cette thèse