Subbayya Sivasankaranarayana Pillai

Subbayya Sivasankaranarayana Pillai was an Indian mathematician who made significant contributions to number theory. He was born on 5 April 1901 in Vallam, a village in Tamil Nadu, India. His mother died a year after his birth and his father when he was in his last year at school. He did his intermediate course and B.Sc Mathematics in the Scott Christian College at Nagercoil and managed to earn a B.A. degree from Maharaja's college, Trivandrum. In 1927, he was awarded a research fellowship at the University of Madras to work among professors K. Ananda Rau and Ramaswamy S. Vaidyanathaswamy. He was from 1929 to 1941 at Annamalai University where he worked as a lecturer. It was in Annamalai University that he did his major work in Waring's problem, a classical problem in number theory that deals with the representation of natural numbers as sums of powers of natural numbers. He proved the Waring's problem for k=4 in 1935 under the further condition of g(4)=19 ahead of Leonard Eugene Dickson who around the same time proved it for g(4)=16. He also showed that g(k) where g(k) is the largest natural number such that every natural number is the sum of at most g(k) kth powers of natural numbers and hence computed the precise value of g(7). He also introduced and studied several concepts and functions in number theory such as Pillai's conjecture, Pillai's arithmetical function, Pillai prime, and Pillai sequence. In 1941 he went to the University of Travancore and a year later to the University of Calcutta as a lecturer (where he was at the invitation of Friedrich Wilhelm Levi). For his achievements he was invited in August 1950, for a year to visit the Institute for Advanced Study, Princeton, United States. He was also invited to participate in the International Congress of Mathematicians at Harvard University as a delegate of the Madras University but he died during the crash of TWA Flight 903 in Egypt on the way to the conference on 31 August 1950. He was only 49 years old when he died. His contribution to Waring's problem was described in 1950 by K. S. Chandrasekharan as almost certainly his best piece of work and one of the very best achievements in Indian Mathematics since Ramanujan. He was also praised by other eminent mathematicians such as G.H. Hardy, Srinivasa Ramanujan, Paul Erdős, and André Weil. He is regarded as one of the greatest Indian mathematicians of the 20th century.