We deal with directed hypergraphs as a tool to model and solve some classes of problems arising in Operations Research and in Computer Science. Concepts such as connectivity, paths and cuts are defined. An extension of the main duality results to a special class of hypergraphs is presented. Algorithms to perform visits of hypergraphs and to find optimal paths are studied in detail. Some applications arising in propositional logic, And-Or graphs, relational data bases and transportation analysis are presented. January 1990 Revised, October 1992 ( * ) This research has been supported in part by the "Comitato Nazionale Scienza e Tecnologia dell'Informazione", National Research Council of Italy, under Grant n.89.00208.12, and in part by research grants from the National Research Council of Canada. 1 Dipartimento di Informatica, Università di Pisa, Italy 2 Département d'Informatique et de Recherche Opérationnelle, Université de Montréal, Canada 2 INTRODUCTION Hypergraphs, a generaliz...

We consider the problem of finding an optimal set of feasible assembly operations in order to derive a desired product from a given set of parts. We show that optimal solutions, under different objective functions, can be obtained by means of computationally efficient hypergraph algorithms. In particular, we consider the case in which one wants to minimize the duration with an unlimited degree of parallelism. Finally, a new fast algorithm is presented in order to assign operations to robots in an optimal way when the degree of parallelism is bounded. Technical Report TR-6/92 March, 1992 (revised: July, 1992) This research has been supported by "Ministero dell'Universit e della Ricerca Scientifica e Tecnologica", National Project on "Gestione dei flussi nei sistemi flessibili di produzione". 2 Introduction In robotic assembly systems, one or more types of items are produced by assembling together several parts given in input, according to a properly defined assembly plan. An asse...