Stelios Kotsios has studied mathematics at the University of Athens, where he graduated in 1983. In 1986 he graduated from the Graduate School of Informatics and Operational Research, Mathematical Department, and in 1993 he receieved his Ph.D. in Applied Mathematics with title: "Controlling Non Linear Discrete Systems." The years 1994-1997 was a postdoctoral researcher and lecturer at University College Dublin, Ireland, working on the chaotic behavior of nonlinear discrete systems. The academic year 1997-1998 he taught Advance Mathematics at the Civil Engineering Department, University of Thessaly and the at the Department of Naval Architecture, Technical Univeristy of Athens. He has also collaborated on research issues, with the Department of Applied Mathematics, National Technical University of Athens. Since 1998 he is a faculty member of the Department of Economics, National and Kapodistrian University of Athens, in the field of Mathematics - Informatics and since 2002 he teaches regularly in the Department of Computer Science at the Open University. The year 2002-03 he taught Mathematics at the then newly established University of Peloponnese.
Prof. Kotsios is concerned with the study, theoretical and applied, of nonlinear discrete systems with input. These systems are described by nonlinear difference equations, mostly coming from the 'Realization' of nonlinear models in discrete time. Specifically, many problems from various scientific fields (eg robotics, economy, aerospace, etc.) are described primarily via continuous nonlinear systems and are studied since then by the help of the relevant theory. In order these methods to be automated, to be executed , in other words, on-line by using proper computational tools, all the above mentioned models have to be discretized and suitable algorithms to be written. While in the linear case this problem has been studied and certain results are available, in the nonlinear case it remains open and quite difficult, due to the complexity of the systems. Prof. Kotsios has studied such nonlinear discrete systems with input and systems with discontinuity, mainly by using symbolic computational methods. Specifically, he has developed algorithms which solve on-line, classical problems of control theory, which have been faced adequate for the linear case but for the nonlinear case, only some theoretical results are available. For instance, some such problems are: realization, stabilization, stability, finding appropriate feedbacks for "driving" a system etc. His results have been published in several international journals and conferences.