This volume contains the papers that have been presented at the Conference on Modeling and Control of Uncertain Systems held in Sopron, Hungary on September 3-7, 1990, organised within the framework of the activities of the System and Decision Sciences Program of IIASA - the International Institute for Applied Systems Analysis. The importance of the subject has drawn the attention of researchers all over the world since several years. In fact, in most actual applications the knowledge about the system under investigation presents aspects of uncertainty due to measurement errors or poor understanding of the rele vant underlying mechanisms. For this reason models that take into account these intrinsic uncertainties have been used and techniques for the analysis of their behavior as well as for their estimation and control have been devel oped. The main ways to deal with uncertainty consist in its description by stochastic processes or in terms of set-valued dynamics and this volume col lects relevant contributions in both directions. However, in order to avoid undesirable distinctions between these approaches, but on the contrary to stress the unity of ideas, we decided to organize the papers according to the alphabetical order of their authors. We should like to take this opportunity to thank IIASA for supporting the Conference and the Hungarian National Member Organization for the kind hospitality in Sopron. Finally we would like to express our gratitude to Ms. Donna Huchthausen for her valuable secretarial assistance. Vienna, February 20, 1991 GIOVANNI B."

In its broadest sense, nonlinear synthesis involves in fact the synthesis of sometimes so phisticated or complex control strategies with the aim of prescribing, or at least influencing, the evolution of complex nonlinear systems. Nonlinear synthesis requires the development of methodologies for modeling complex systems, for the analysis of nonlinear models, and for the systematic design of control schemes or feedback laws which can achieve a wide variety of prescribed objectives. The modeling, analysis and control of complex systems in the face of uncertainty form on of the major components of the current research program in the Department of Systems and Decision Sciences (SDS) at the International Institute for Applied Systems Analysis (IIASA). In June 1989, a IIASA workshop on Nonlinear Synthesis, sponsored by SDS, was held in Sopron, Hungary. We are proud to present this volume as the proceedings of this workshop, a workshop attened by prominent researchers in nonlinear systems from both the East and the West. Since the promotion and encouragement of scientific cooperation between researchers in the East and in the West is one of the goals at IIASA, we feel the Sopron Conference on Nonlinear Synthesis was very successful. Moreover, we were especially pleased by the impressive new advances presented at the workshop which, in this volume, are now part of the conference record."

This volume contains the papers that have been presented at the Conference on Modeling and Control of Uncertain Systems held in Sopron, Hungary on September 3-7, 1990, organised within the framework of the activities of the System and Decision Sciences Program of IIASA - the International Institute for Applied Systems Analysis. The importance of the subject has drawn the attention of researchers all over the world since several years. In fact, in most actual applications the knowledge about the system under investigation presents aspects of uncertainty due to measurement errors or poor understanding of the rele vant underlying mechanisms. For this reason models that take into account these intrinsic uncertainties have been used and techniques for the analysis of their behavior as well as for their estimation and control have been devel oped. The main ways to deal with uncertainty consist in its description by stochastic processes or in terms of set-valued dynamics and this volume col lects relevant contributions in both directions. However, in order to avoid undesirable distinctions between these approaches, but on the contrary to stress the unity of ideas, we decided to organize the papers according to the alphabetical order of their authors. We should like to take this opportunity to thank IIASA for supporting the Conference and the Hungarian National Member Organization for the kind hospitality in Sopron. Finally we would like to express our gratitude to Ms. Donna Huchthausen for her valuable secretarial assistance. Vienna, February 20, 1991 GIOVANNI B.