Andrew Casson

Andrew Casson
Casson in 1991
Born	(1943-01-22)January 22, 1943 London, England.
Died	September 5, 2025(2025-09-05) (aged 82) Fairfield, Connecticut, U.S.A.
Education	University of Liverpool
Awards	Oswald Veblen Prize in Geometry (1991) Fellow of the Royal Society (1998)
Scientific career
Fields	Mathematics
Workplaces	Yale University University of California, Berkeley University of Texas at Austin
Doctoral advisor	C. T. C. Wall
Doctoral students	Andrew Ranicki, Gregory Kuperberg, Daniel Allcock, Mahan Mitra, Stephen Bigelow, Danny Calegari

Andrew John Casson (January 22, 1943 – September 5, 2025) was a mathematician, working in the area of geometric topology. Casson was the Philip Schuyler Beebe Professor of Mathematics at Yale University until his retirement.

Education and career

Casson was educated at Latymer Upper School and Trinity College, Cambridge, where he graduated with a BA in the Mathematical Tripos in 1965. His doctoral advisor at the University of Liverpool was C. T. C. Wall, but he never completed his doctorate; instead what would have been his Ph.D. thesis became his fellowship dissertation as a research fellow at Trinity College.

Casson was Professor of Mathematics at the University of Texas at Austin from 1981 to 1986, at the University of California, Berkeley from 1986 to 2000, and at Yale from 2000 until his retirement.

Work

Casson worked in both high-dimensional manifold topology and three- and four-dimensional topology, using both geometric and algebraic techniques. Among other discoveries, he contributed to the disproof of the manifold Hauptvermutung, introduced the Casson invariant, a modern invariant for three-manifolds, and Casson handles, used in Michael Freedman's proof of Freedman's classification and subsequently the four-dimensional Poincaré conjecture.

Awards

In 1991, he was awarded the Oswald Veblen Prize in Geometry by the American Mathematical Society. In 1998, he was elected to Fellowship of the Royal Society.

External links

• Obituary
• Official Home Page
• The Hauptvermutung book (including Casson's 1967 Trinity College fellowship dissertation)
• March 1991 issue of the Notices of the AMS Contains the announcement of the Veblen Prize.
• Proceedings of the Casson Fest (Arkansas and Texas 2003) A conference to celebrate Casson's 60th birthday, with biographical information.
• Photos from conference, including the `honorary degree' presented to Casson by the participants
• Andrew Casson at the Mathematics Genealogy Project (includes list of PhD students.)