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M.I.T. Professor Emeritus Irving Segal, a pioneer in the fields of functional analysis and harmonic analysis,died suddenly while walking near his home in Lexington, MA, on Sunday evening, Aug. 30. He was 79 years old.

An M.I.T. faculty member for 38 years, Professor Segal was one of the Department of Mathematics' most dedicated teachers, contributing significantly to the review and upgrading of its curriculum. He was advisor to a number of outstanding graduate students, among themM.I.T. professors Isadore Singer and Bertram Kostant (now emeritus) and Princeton University professor Edward Nelson.

Born in the Bronx on Sept. 13, 1918, Professor Segal was raised in Trenton, N.J., and received the B.A. from Princeton in 1937 and the PhD from Yale in 1940, both in mathematics. He was an instructor at HarvardUniversity in 1941 and a research associate at Princeton from 1941-43 before entering the US Army. After military service, doing ballistics research at the Aberdeen Proving Grounds,Professor Segal did research work at the Institute for Advanced Study from 1945-48 before moving to the University of Chicago. At the University of Chicago he was an assistant professor from 1948-53, associate professor from 1953-57, and a full professor from 1957-60. He came to M.I.T. in 1960 as a professor of mathematics and assumed emeritus status in 1989.

Professor Segal had visiting appointments for various periodsat Columbia University, La Sorbonne, Lund University,University of Pisa, Aarhus University, College de France, Institute of Mathematics and Theoretical Physics, Copenhagan; and at the University of Moscow.

Early in his career, Professor Segal was concerned with applications of algebraic methods to fundamental physics,in particular to the foundations of quantum field theory.In 1947 he introduced a system of postulates for generalquantum theory which spawned a great deal of active research. He was able to generalize major portions of the seminal work of Norbert Wiener. His theory ofnon-commutative integration provided anextraordinary generalization of the Plancherel theoremfor the Fourier transform to general locally compact groups. More recently, Professor Segal pursued applicationsof his ``chronometric theory'' to various studies in astrophysics, leading to a parameter-free theory of thered-shift and an alternative model of the universe.

Professor Segal, a member of the American Astronomical, Mathematical, and Physical Societies, was elected to theAmerican Academy of Arts and Sciences, the Royal DanishAcademy of Sciences, and the National Academy of Sciences.A three-time John Simon Guggenheim Fellow (1947, 1951, and1967) and recipient of the Alexander von Humboldt Award in1981, he was a founder and managing editor of theJournal of Functional Analysis and authored three books andmore than 200 papers.

Professor Segal is survived by his wife, Dr. Martha (Fox) Segal of Lexington, and four children, a daughter Miriam, 8 years oldwith Martha Segal, and three children by his first wife, Osa MacLaneof Chicago, who also survives:William of Bethesda, MD, Andrew of Espinola, NM, andKaren of New York City.

This information was provided by the M.I.T. Department of Mathematics.