Succinct Discrete Time Approximations of Distributed Hybrid Automata


Prof. P.S. Thiagarajan (Department of Computer Science, National University of Singapore)


We consider a network of controllers that observe and control a plant whose state space is determined by a set of continuous variables. We assume that at any instant, these variables are evolving at (different) constant rates. Each controller can switch the rates of a designated subset of the continuous variables; its 'write' variables. These mode changes are determined by the current values of a designated subset of the variables that a controller can observe; its 'read' variables. We require the 'write' variables to be exclusive while the 'read' variables may be shared.

We study the discrete time behavior of such systems modeled as a network of hybrid automata. We show that the set of global control state sequences displayed by the network is regular. More importantly, we show that one can effectively and succinctly represent this regular language as a product of local finite state automata.


P.S. Thiagarajan is a Professor in the Department of Computer Science and is the Vice Dean (Research) in the School of Computing, NUS. He is also a Senior Faculty Member of the NUS Graduate School of Integrative Science and Engineering (NGS). He received a B.Tech (Electronics) degree from the Indian Institute of Technology, Madras, India (1970) and a PhD degree (Computer Science) from Rice University, Houston, Texas, USA (1972). He has been a Research Associate at MIT, a Research Scientist at GMD, St. Augustin, Germany, an Associate Professor in the CS Dept. of Aarhus University, an Associate Professor at the Institute of Mathematical Science, Chennai, India and a founding professor of the Chennai Mathematical Institute, Chennai, India.

Starting with Petri nets, he has extensively studied various aspects of the theory of distributed systems. Since moving to NUS, he has focused on real time, hybrid and embedded computing systems. In the last few years, computational systems biology has become his main field of research. He is a Fellow of the Indian Academy of Sciences and a Fellow of the Indian National Academy of Sciences and has served on the Governing Council of the European association for Theoretical Computer Science. He is currently a member of the Governing Council of the Chennai Mathematical Institute.