Mathematician Veeravalli Seshadri Varadarajan, Professor Emeritus and Distinguished Research Professor at University of California, Los Angeles, died last month, the university announced. He was 81.
According to an obituary posted on the UCLA website, professor Varadarajan “led a research career of lasting international influence.” He worked in UCLA for 49 years until his retirement in 2014.
The obituary written by UCLA mathematics Professor Don Blasius, with assistance of his colleagues, said Varadarajn, was a superb colleague who inspired respect and devotion among those lucky enough to work with him. He did sustained and significant work in at least five areas over his long career.
Born in 1937 in Chennai, India, Varadarajan received his undergraduate degree in 1957 from Presidency College, Madras and his doctorate in 1960 from the Indian Statistical Institute in Calcutta, under the supervision of C. R. Rao. With the others of the ‘famous four’ from ISI in this period — K.R. Parthasarathy, R. Ranga Rao, and S.R.S. Varadhan — Raja, (as Varadarajan was known), is regarded as someone who played an early important role in the development of probability theory in India, the obituary said.
After short periods at the Institute for Advanced Study and the University of Washington, Seattle, Varadarajan joined the Department of Mathematics at UCLA in 1965. In March 2019, Varadarajan and his wife donated $1 million to the Department of Mathematics at UCLA to establish the Ramanujan Visiting Professorship.
Varadarajan's early work, including his doctoral thesis, was in the area of probability theory. He then moved into representation theory where he has done some of his best known work.
In the 1980s, he wrote a series of papers with Donald Babbitt on the theory of differential equations with irregular singularities. His latest work has been in supersymmetry.
He introduced Kostant–Parthasarathy–Ranga Rao–Varadarajan determinants along with Bertram Kostant, K. R. Parthasarathy and R. Ranga Rao in 1967, the Trombi–Varadarajan theorem in 1972 and the Enright–Varadarajan modules in 1975.
He also wrote several textbooks for graduate students. According to the UCLA obituary, “his 1974 ‘Lie Groups, Lie Algebras, and Representations’ “was the first of its kind and remains a standard reference text.” Some of the other textbooks and papers he wrote include “An Introduction to Harmonic Analysis on Semisimple Lie Group,” a 2004 exposition “Supersymmetry for Mathematicians: an introduction,” which became an American Mathematical Society bestseller, and a 2006 collaborative paper which defined and developed the notion of a unitary representation of a Lie supergroup. In addition, with R. Gangolli, he published in 1988 a 385 page research/expository monograph in the famous Ergebnisse series of the Springer press. Varadarajan was managing editor of the Pacific Journal of Mathematics for 30 years.
His international recognitions include an honorary doctorate in physics from the University of Genoa, and the Lars Onsager medal from the Norwegian University of Science and Technology. He was a speaker at the International Congress of Mathematicians in 1974, considered “a high honor for a mathematician at any stage of career.”
After retirement, Varadarajan, continued his research. With R. Gangolli, he edited important unpublished manuscripts of Harish-Chandra in which theorems announced by Harish-Chandra before his early death are given proof. This volume forms now forms the fifth of Harish-Chandra’s collected papers. The first four volumes were edited by Varadarajan alone.
In 1992 Varadarajan had a major heart attack that left him physically weakened for life, which led him to a change of perspective on research,” the obituary said.
Outside of mathematics, Varadarajan loved classical Western and Indian music, the obituary said. Mozart was his particular favorite. He was also fond of mystery novels, “especially of the English genre, and also of television shows with such plots.” He also loved sports. Although cricket had been his first passion, in Los Angeles he became a serious Lakers fan. “Perhaps above all other recreations, he loved good conversation with friends,” the obit said. “He had a prodigious memory and could move effortlessly in conversation between his favorite themes.”