- Email: [email protected]
For Lotfi Zadeh on his 90th birthday
Scientia Iranica D (2011) 18 (3), 697–698
Sharif University of Technology Scientia Iranica Transactions D: Computer Science & Engineering and Electrical Engineering www.sciencedirect.com
Correspondence
For Lotfi Zadeh on his 90th birthday I met Lotfi Zadeh in 1965 when he arranged for me to attend a conference devoted to Mathematical Programming and Optimal Control in Colorado Springs, Colorado. Lotfi was undoubtedly one of the major inspirations behind the organization of this conference. The fact that Optimal Control Problems in Discrete-time could be viewed as Mathematical Programming Problems, and the Maximum Principle could be obtained using the Duality Theory of Nonlinear Programming, perhaps not in full generality, was recognized at that time. To view Optimal Control Problems as Mathematical Programming Problems in Infinite Dimensional Spaces required new ideas and the development of new technical apparatus. At Berkeley, the doctoral theses of Pravin Varaiya and Richard Van Slyke, written under Lotfi Zadeh’s direction, were devoted to Mathematical Programming in Infinite Dimensional Spaces. A part of my thesis, written at Imperial College, London, was also devoted to Mathematical Programming in Infinite Dimensional Spaces. One of the high points of this meeting was the presence of Soviet mathematicians L.S. Pontryagin and R.V. Gamkrelidze. The memory of this meeting is still quite fresh in my mind. This was a time of great ferment in the Systems and Control Field. Elsewhere, I have characterized the advent of the State Space Theory of Systems, specially linear systems (time-invariant and time-varying), and the reconciliation of the input–output and state-space view of systems as a scientific revolution in the sense of Thomas Kuhn. The contribution of Lotfi to this revolution is decisive. The book, Linear Systems Theory: A State Space Approach, by Lotfi Zadeh and the late Charles Desoer, both a text book and a monograph, set new standards of mathematical and conceptual rigor in engineering. One may say, it ushered in a new field-mathematical engineering. The influence of this book on successive generations of students, myself included, cannot be overstated. At about the same time, a parallel effort was going on in an attempt to unify Linear Systems Theory and Automata 1026-3098 © 2011 Sharif University of Technology. Production and hosting by Elsevier B.V. All rights reserved. Peer review under responsibility of Sharif University of Technology. doi:10.1016/j.scient.2011.04.027
Theory. More importantly, Lotfi recognized the need for bringing Electrical Engineering and Computer Science together, intellectually and institutionally. In a certain sense, he foresaw the inevitability of the digital world being thrust upon us and that this needed to be reflected in the structure of our educational system. The existence of an Electrical Engineering and Computer Science Department at Berkeley is very much Lotfi’s creation. We live in an uncertain world. John Maynard Keynes recognized that the development of an intellectual framework for dealing with uncertainty is the fundamental problem of Economics. Nearer to the control field, the founders of feedback control – Black, Nyquist, Bode – clearly understood that the need for feedback control arises from dealing with the effects of modeling uncertainty (in their case, modeling uncertainty in the components of feedback amplifiers) on the performance of a system. The distinction between model uncertainty and measurement, or external uncertainty, is a non-trivial distinction. The question then arises as to how one should model uncertainty, be it in structure, measurement or environment. We owe the fundamental insight to Lotfi Zadeh that it is not possible, or does not make sense, to model uncertainty in every situation probabilistically. For one thing, to obtain a probabilistic model, a probability space needs to be fabricated and it is unclear how to do that unless its existence can be justified on physical grounds. This is particularly dubious in Economics, Social Science and Cognitive Science. In my view, the major failure of the field of Artificial Intelligence has been its inability to deal with problems of Perception, Cognition and Situated Action. It is essential that an intellectual framework for dealing with ambiguity and uncertainty be in place if we are going to make a scientific contribution here. Lotfi’s answer to this challenge has been the development of the theory of Fuzzy Sets and Fuzzy Logic. He wanted to develop a theory which would be precise and an alternative to probability theory in modeling ambiguity and uncertainty. His ideas on soft computing and computing with words are also meant to provide a theoretical framework for understanding the behavior of systems which requires a less rigid description. This is surely a step in the right direction. I want to end this short tribute by pointing out another dimension to Lotfi’s intellect: what I would call the moral dimension. He has been one of the few voices to protest the intellectual subversion of the university under the corrosive influence of money. This is particularly glaring in the so-called ‘‘elite research’’ universities. As he remarked, ‘‘We used to look for money to do research. Now, we look for research to get money’’. I find it astonishing that the primary function of a
698
Correspondence / Scientia Iranica, Transactions D: Computer Science & Engineering and Electrical Engineering 18 (2011) 697–698
research university is often framed as one of competing against other research universities. Lotfi also has spoken eloquently in public forums about the savage nature of modern capitalism as practiced in the USA (and UK) today. I hope my colleagues at my own institution and elsewhere are listening. S.K. Mitter received his Ph.D. degree from Imperial College of Science and Technology in 1965. He taught at Case Western Reserve University from 1965 to 1969. He joined MIT in 1969, where he has been Professor of Electrical Engineering since 1973. He was Director of the MIT Laboratory for Information and Decision Systems from 1981 to 1999. He was also a Professor of Mathematics at the Scuola Normale, Pisa, Italy, from 1986 to 1996. He has held visiting positions at Imperial College, London; University of Groningen, Holland; INRIA, France; Tata Institute of Fundamental Research, India and ETH, Zürich, Switzerland; and several American universities. Professor Mitter was awarded the AACC Richard E. Bellman Control Heritage Award for 2007. He was McKay Professor at the University of California, Berkeley, in March 2000, and held the Russell-Severance-Springer Chair in Fall 2003. He
is a Fellow of the IEEE and a Member of the National Academy of Engineering. He is winner of the 2000 IEEE Control Systems Award. He was elected a Foreign Member of Istituto Veneto di Scienze, Lettere ed Arti in 2003. His current research interests are Communication and Control in a Networked Environment, the Relationship of Statistical and Quantum Physics to Information Theory and Control and Autonomy and Adaptiveness for Integrative Organization.
S.K. Mitter Department of Electrical Engineering and Computer Science; and The Laboratory for Information and Decision Systems, MIT Cambridge, MA 02139, USA E-mail address: [email protected]. 22 January 2011
Sharif University of Technology Scientia Iranica Transactions D: Computer Science & Engineering and Electrical Engineering www.sciencedirect.com
Correspondence
For Lotfi Zadeh on his 90th birthday I met Lotfi Zadeh in 1965 when he arranged for me to attend a conference devoted to Mathematical Programming and Optimal Control in Colorado Springs, Colorado. Lotfi was undoubtedly one of the major inspirations behind the organization of this conference. The fact that Optimal Control Problems in Discrete-time could be viewed as Mathematical Programming Problems, and the Maximum Principle could be obtained using the Duality Theory of Nonlinear Programming, perhaps not in full generality, was recognized at that time. To view Optimal Control Problems as Mathematical Programming Problems in Infinite Dimensional Spaces required new ideas and the development of new technical apparatus. At Berkeley, the doctoral theses of Pravin Varaiya and Richard Van Slyke, written under Lotfi Zadeh’s direction, were devoted to Mathematical Programming in Infinite Dimensional Spaces. A part of my thesis, written at Imperial College, London, was also devoted to Mathematical Programming in Infinite Dimensional Spaces. One of the high points of this meeting was the presence of Soviet mathematicians L.S. Pontryagin and R.V. Gamkrelidze. The memory of this meeting is still quite fresh in my mind. This was a time of great ferment in the Systems and Control Field. Elsewhere, I have characterized the advent of the State Space Theory of Systems, specially linear systems (time-invariant and time-varying), and the reconciliation of the input–output and state-space view of systems as a scientific revolution in the sense of Thomas Kuhn. The contribution of Lotfi to this revolution is decisive. The book, Linear Systems Theory: A State Space Approach, by Lotfi Zadeh and the late Charles Desoer, both a text book and a monograph, set new standards of mathematical and conceptual rigor in engineering. One may say, it ushered in a new field-mathematical engineering. The influence of this book on successive generations of students, myself included, cannot be overstated. At about the same time, a parallel effort was going on in an attempt to unify Linear Systems Theory and Automata 1026-3098 © 2011 Sharif University of Technology. Production and hosting by Elsevier B.V. All rights reserved. Peer review under responsibility of Sharif University of Technology. doi:10.1016/j.scient.2011.04.027
Theory. More importantly, Lotfi recognized the need for bringing Electrical Engineering and Computer Science together, intellectually and institutionally. In a certain sense, he foresaw the inevitability of the digital world being thrust upon us and that this needed to be reflected in the structure of our educational system. The existence of an Electrical Engineering and Computer Science Department at Berkeley is very much Lotfi’s creation. We live in an uncertain world. John Maynard Keynes recognized that the development of an intellectual framework for dealing with uncertainty is the fundamental problem of Economics. Nearer to the control field, the founders of feedback control – Black, Nyquist, Bode – clearly understood that the need for feedback control arises from dealing with the effects of modeling uncertainty (in their case, modeling uncertainty in the components of feedback amplifiers) on the performance of a system. The distinction between model uncertainty and measurement, or external uncertainty, is a non-trivial distinction. The question then arises as to how one should model uncertainty, be it in structure, measurement or environment. We owe the fundamental insight to Lotfi Zadeh that it is not possible, or does not make sense, to model uncertainty in every situation probabilistically. For one thing, to obtain a probabilistic model, a probability space needs to be fabricated and it is unclear how to do that unless its existence can be justified on physical grounds. This is particularly dubious in Economics, Social Science and Cognitive Science. In my view, the major failure of the field of Artificial Intelligence has been its inability to deal with problems of Perception, Cognition and Situated Action. It is essential that an intellectual framework for dealing with ambiguity and uncertainty be in place if we are going to make a scientific contribution here. Lotfi’s answer to this challenge has been the development of the theory of Fuzzy Sets and Fuzzy Logic. He wanted to develop a theory which would be precise and an alternative to probability theory in modeling ambiguity and uncertainty. His ideas on soft computing and computing with words are also meant to provide a theoretical framework for understanding the behavior of systems which requires a less rigid description. This is surely a step in the right direction. I want to end this short tribute by pointing out another dimension to Lotfi’s intellect: what I would call the moral dimension. He has been one of the few voices to protest the intellectual subversion of the university under the corrosive influence of money. This is particularly glaring in the so-called ‘‘elite research’’ universities. As he remarked, ‘‘We used to look for money to do research. Now, we look for research to get money’’. I find it astonishing that the primary function of a
698
Correspondence / Scientia Iranica, Transactions D: Computer Science & Engineering and Electrical Engineering 18 (2011) 697–698
research university is often framed as one of competing against other research universities. Lotfi also has spoken eloquently in public forums about the savage nature of modern capitalism as practiced in the USA (and UK) today. I hope my colleagues at my own institution and elsewhere are listening. S.K. Mitter received his Ph.D. degree from Imperial College of Science and Technology in 1965. He taught at Case Western Reserve University from 1965 to 1969. He joined MIT in 1969, where he has been Professor of Electrical Engineering since 1973. He was Director of the MIT Laboratory for Information and Decision Systems from 1981 to 1999. He was also a Professor of Mathematics at the Scuola Normale, Pisa, Italy, from 1986 to 1996. He has held visiting positions at Imperial College, London; University of Groningen, Holland; INRIA, France; Tata Institute of Fundamental Research, India and ETH, Zürich, Switzerland; and several American universities. Professor Mitter was awarded the AACC Richard E. Bellman Control Heritage Award for 2007. He was McKay Professor at the University of California, Berkeley, in March 2000, and held the Russell-Severance-Springer Chair in Fall 2003. He
is a Fellow of the IEEE and a Member of the National Academy of Engineering. He is winner of the 2000 IEEE Control Systems Award. He was elected a Foreign Member of Istituto Veneto di Scienze, Lettere ed Arti in 2003. His current research interests are Communication and Control in a Networked Environment, the Relationship of Statistical and Quantum Physics to Information Theory and Control and Autonomy and Adaptiveness for Integrative Organization.
S.K. Mitter Department of Electrical Engineering and Computer Science; and The Laboratory for Information and Decision Systems, MIT Cambridge, MA 02139, USA E-mail address: [email protected]. 22 January 2011