Nelson Onuchic was born in Brodósqui, SP, on March 11, 1926, and died in São Carlos, SP, on September 3, 1999. He was an outstanding Brazilian mathematician who had an important influence on the birth and development of mathematical research in Brazil in the second part of the 20th century. In the first years, his contributions lay on Topology and, later, on Ordinary Differential Equations and Functional Differential Equations in which he collaborated with some of the most important mathematicians at the time in this area, such as J.L. Massera, ‎J.J. Schäffer, V. Lakshmikantham, P. Hartman and J.K. Hale.

Nelson Onuchic studied at Mackenzie University in São Paulo, at the Technological Institute of Aeronautics (ITA) in São José dos Campos, SP, and at the University of São Paulo where he received his doctorate in 1957 under the supervision of Chaim Samuel Hönig.

He worked at ITA from 1951 to 1958. In 1958, he began the work of implementing a Bachelor in Science degree in Mathematics at the Faculty of Philosophy, Sciences and Letters of Rio Claro, SP, where he lived until 1966. Then, he moved to São Carlos, SP. From 1961 to 1962, he was a John Simon Guggenheim Memorial Foundation fellow at the Research Institute for Advanced Studies (RIAS), in Baltimore, USA. In 1971, he was one of the founders of the Instituto de Ciências Matemáticas de São Carlos (ICMSC), now known as Instituto de Ciências Matemáticas e de Computação (ICMC), of the University of São Paulo, where he was director from December 6, 1973 to April 22, 1974 and Full Professor. He was the advisor of nine doctoral theses. On April 29, 1983, he received the title of Professor Emeritus at ICMSC-USP.

In 1964, professor Nelson Onuchic was admitted as an Associate Member of the Brazilian Academy of Sciences (ABC). In 1976, he became a Full Member of it. He was also a founding member of the Academy of Sciences of the State of São Paulo. He was a member of the Society of Mathematics of São Paulo and was a founding member of the Brazilian Society of Mathematics.

He married Lourdes de La Rosa Onuchic, also a mathematician whose research was focused on education issues. They had a daughter and three sons, two of them with an outstanding university career, the outstanding physicist José Nelson Onuchic and the physician Luiz Fernando Onuchic (Professor at the Faculty of Medicine of USP in São Paulo). The other two, Paulo Eduardo Onuchic and Maria Inês Onuchic Schultz were successful in the private sector.

Translated to English from the text in Wikipedia written by professors Hildebrando Rodrigues and Juan Sola-Morales.