Scientia Iranica D (2011) 18 (3), 697–698

Sharif University of Technology

Scientia IranicaTransactions 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 toattend a conference devoted to Mathematical Programmingand Optimal Control in Colorado Springs, Colorado. Lotfiwas undoubtedly one of the major inspirations behind theorganization of this conference. The fact that Optimal ControlProblems in Discrete-time could be viewed as MathematicalProgramming Problems, and the Maximum Principle could beobtained using the Duality Theory of Nonlinear Programming,perhaps not in full generality, was recognized at that time. Toview Optimal Control Problems as Mathematical ProgrammingProblems in Infinite Dimensional Spaces required new ideasand the development of new technical apparatus. At Berkeley,the doctoral theses of Pravin Varaiya and Richard VanSlyke, written under Lotfi Zadeh’s direction, were devoted toMathematical Programming in Infinite Dimensional Spaces. Apart of my thesis, written at Imperial College, London, was alsodevoted to Mathematical Programming in Infinite DimensionalSpaces. One of the high points of this meeting was the presenceof 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 andControl Field. Elsewhere, I have characterized the advent ofthe State Space Theory of Systems, specially linear systems(time-invariant and time-varying), and the reconciliation of theinput–output and state-space view of systems as a scientificrevolution in the sense of Thomas Kuhn. The contribution ofLotfi to this revolution is decisive. The book, Linear Systems The-ory: A State Space Approach, by Lotfi Zadeh and the late CharlesDesoer, both a text book and a monograph, set new standardsof mathematical and conceptual rigor in engineering. One maysay, it ushered in a new field-mathematical engineering. The in-fluence of this book on successive generations of students, my-self included, cannot be overstated.

At about the same time, a parallel effort was going onin an attempt to unify Linear Systems Theory and Automata

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doi:10.1016/j.scient.2011.04.027

Theory. More importantly, Lotfi recognized the need forbringing Electrical Engineering and Computer Science together,intellectually and institutionally. In a certain sense, he foresawthe inevitability of the digital world being thrust upon usand that this needed to be reflected in the structure of oureducational system. The existence of an Electrical Engineeringand Computer Science Department at Berkeley is very muchLotfi’s creation.

We live in an uncertain world. John Maynard Keynesrecognized that the development of an intellectual frameworkfor dealing with uncertainty is the fundamental problemof Economics. Nearer to the control field, the founders offeedback control – Black, Nyquist, Bode – clearly understoodthat the need for feedback control arises from dealing withthe effects of modeling uncertainty (in their case, modelinguncertainty in the components of feedback amplifiers) onthe performance of a system. The distinction between modeluncertainty and measurement, or external uncertainty, is anon-trivial distinction. The question then arises as to how oneshould model uncertainty, be it in structure, measurement orenvironment. We owe the fundamental insight to Lotfi Zadehthat it is not possible, or does not make sense, to modeluncertainty in every situation probabilistically. For one thing,to obtain a probabilistic model, a probability space needs to befabricated and it is unclear how to do that unless its existencecan be justified on physical grounds. This is particularly dubiousin Economics, Social Science and Cognitive Science. In my view,the major failure of the field of Artificial Intelligence has beenits inability to deal with problems of Perception, Cognition andSituated Action. It is essential that an intellectual framework fordealing with ambiguity and uncertainty be in place if we aregoing to make a scientific contribution here.

Lotfi’s answer to this challenge has been the developmentof the theory of Fuzzy Sets and Fuzzy Logic. He wanted todevelop a theory which would be precise and an alternative toprobability theory in modeling ambiguity and uncertainty. Hisideas on soft computing and computing with words are alsomeant to provide a theoretical framework for understandingthe 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 anotherdimension to Lotfi’s intellect: what I would call the moraldimension. He has been one of the few voices to protest theintellectual subversion of the university under the corrosiveinfluence of money. This is particularly glaring in the so-called‘‘elite research’’ universities. As he remarked, ‘‘We used to lookfor money to do research. Now, we look for research to getmoney’’. 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 againstother research universities. Lotfi also has spoken eloquently inpublic forums about the savage nature of modern capitalism aspracticed in the USA (and UK) today. I hopemy colleagues atmyown institution and elsewhere are listening.

S.K. Mitter received his Ph.D. degree from Imperial College of Science andTechnology in 1965. He taught at Case Western Reserve University from1965 to 1969. He joined MIT in 1969, where he has been Professor of Elec-trical Engineering since 1973. He was Director of the MIT Laboratory forInformation and Decision Systems from 1981 to 1999. He was also a Profes-sor of Mathematics at the Scuola Normale, Pisa, Italy, from 1986 to 1996. Hehas held visiting positions at Imperial College, London; University of Gronin-gen, Holland; INRIA, France; Tata Institute of Fundamental Research, Indiaand ETH, Zürich, Switzerland; and several American universities. ProfessorMitter was awarded the AACC Richard E. Bellman Control Heritage Award for2007. He was McKay Professor at the University of California, Berkeley, inMarch 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 Engineer-ing. He is winner of the 2000 IEEE Control Systems Award. He was electeda Foreign Member of Istituto Veneto di Scienze, Lettere ed Arti in 2003. Hiscurrent research interests are Communication and Control in a NetworkedEnvironment, the Relationship of Statistical and Quantum Physics to Infor-mation Theory and Control and Autonomy and Adaptiveness for IntegrativeOrganization.

S.K. MitterDepartment of Electrical Engineering and Computer Science;

and The Laboratory for Information and Decision Systems,MIT Cambridge, MA 02139, USA

E-mail address:mitter@mit.edu.

22 January 2011