Kenneth Alan Ribet (/ˈrɪbɪt/; born June 28, 1948) is an American mathematician working in algebraic number theory and algebraic geometry. He is known for the Herbrand–Ribet theorem and Ribet's theorem, which were key ingredients in the proof of Fermat's Last Theorem, as well as for his service as President of the American Mathematical Society from 2017 to 2019. He is currently a professor of mathematics at the University of California, Berkeley.
Ken Ribet  

Born  June 28, 1948 
Nationality  American 
Alma mater  Brown University Harvard University 
Known for  Ribet's Theorem 
Awards 

Scientific career  
Fields  Mathematics 
Institutions  University of California, Berkeley 
Doctoral advisor  John Tate 
Doctoral students  Frank Calegari Samit Dasgupta Bjorn Poonen 
Kenneth Ribet was born in Brooklyn, New York to parents David Ribet and Pearl Ribet, both Jewish, on June 28, 1948.^{[1]} As a student at Far Rockaway High School, Ribet was on a competitive mathematics team, but his first field of study was chemistry.^{[2]}
Ribet earned his bachelor's degree and master's degree from Brown University in 1969.^{[3]}^{[4]} In 1973, Ribet received Ph.D. from Harvard University under the supervision of John Tate.^{[3]}^{[5]}^{[4]}
After receiving his doctoral degree, Ribet taught at Princeton University for three years before spending two years doing research in Paris.^{[3]} In 1978, Ribet joined the Department of Mathematics at the University of California, Berkeley, where he served three separate terms as supervisor of the department's graduate program, supervisor of the department's undergraduate program, and supervisor of the department's development.^{[3]}
Ribet has served as an editor for several mathematics journals, a book series editor for the Cambridge University Press, and a book series editor for Springer.^{[3]} He also served on the United States National Committee for Mathematics, representing the United States at the International Mathematical Union, and was the Chair of the Mathematics section of the National Academy of Sciences.^{[3]}
From February 1, 2017 to January 31, 2019, Ribet was President of the American Mathematical Society.^{[6]}
Ribet's contributions in number theory and algebraic geometry were described by Benedict Gross and Barry Mazur as being "key to our understanding of the connections between the theory of modular forms and the ℓadic representations of the absolute Galois group of the field of rational numbers."^{[3]}
Ribet is credited with paving the way towards Andrew Wiles's proof of Fermat's Last Theorem. In 1986, Ribet proved that the epsilon conjecture formulated by JeanPierre Serre was true, and thereby proved that Fermat's Last Theorem would follow from the Taniyama–Shimura conjecture. Crucially it also followed that the full conjecture was not needed, but a special case, that of semistable elliptic curves, sufficed.^{[7]} An earlier theorem of Ribet's, the Herbrand–Ribet theorem, is the converse to Herbrand's theorem on the divisibility properties of Bernoulli numbers and is also related to Fermat's Last Theorem.^{[8]}^{[9]}^{[10]}^{[11]}
Ribet received the Fermat Prize in 1989 jointly with Abbas Bahri.^{[6]}^{[3]} He was elected to the American Academy of Arts and Sciences in 1997 and the National Academy of Sciences in 2000.^{[6]}^{[3]}^{[4]} In 2012, he became a Fellow of the American Mathematical Society.^{[12]}^{[6]} In 2017, Ribet received the Brouwer Medal.^{[13]}
In 1988, Ribet was inducted as a vigneron d'honneur by the Jurade de SaintÉmilion.^{[4]} In 1998, Ribet received an honorary doctorate from Brown University.^{[4]}
Ribet is married to statistician Lisa Goldberg.^{[14]}