Sidney Martin Webster (born 12 November 1945 in

Danville, Illinois Danville is a city in Vermilion County, Illinois, United States, and its county seat. The populations was 29,204 as of the 2020 census. It is the principal city of the Danville micropolitan area. History The area that is now Danville was on ...

) is an American mathematician, specializing in multidimensional complex analysis. After military service, Webster attended the University of California, Berkeley as an undergraduate and then as a graduate student, receiving a PhD in 1975 under the supervision of

Shiing-Shen Chern Shiing-Shen Chern (; , ; October 26, 1911 – December 3, 2004) was a Chinese American mathematician and poet. He made fundamental contributions to differential geometry and topology. He has been called the "father of modern differential geome ...

with thesis ''Real hypersurfaces in complex space''. Webster was a faculty member at Princeton University from 1975 to 1980 and at the University of Minnesota from 1980 to 1989. In 1989 he became a full professor at the

University of Chicago The University of Chicago (UChicago, Chicago, or UChi) is a Private university, private research university in Chicago, Illinois, United States. Its main campus is in the Hyde Park, Chicago, Hyde Park neighborhood on Chicago's South Side, Chic ...

. He has held visiting positions at the

University of Wuppertal The University of Wuppertal (''Universität Wuppertal'') is a German scientific institution located in Wuppertal in the state of North Rhine-Westphalia, Germany. The university's official name in German is ''Bergische Universität Wuppertal'' ...

Rice University William Marsh Rice University, commonly referred to as Rice University, is a Private university, private research university in Houston, Houston, Texas, United States. Established in 1912, the university spans 300 acres. Rice University comp ...

, and

ETH Zurich ETH Zurich (; ) is a public university in Zurich, Switzerland. Founded in 1854 with the stated mission to educate engineers and scientists, the university focuses primarily on science, technology, engineering, and mathematics. ETH Zurich ran ...

. Webster was a Sloan Fellow for the academic year 1979–1980. In 1994 in Zurich he was an invited speaker of the

International Congress of Mathematicians The International Congress of Mathematicians (ICM) is the largest conference for the topic of mathematics. It meets once every four years, hosted by the International Mathematical Union (IMU). The Fields Medals, the IMU Abacus Medal (known before ...

. In 2001 he received, jointly with László Lempert, the

Stefan Bergman Prize The Stefan Bergman Prize is a mathematics award, funded by the estate of the widow of mathematician Stefan Bergman and supported by the American Mathematical Society. The award is granted for mathematical research in: "1) the theory of the kernel ...

from the

American Mathematical Society The American Mathematical Society (AMS) is an association of professional mathematicians dedicated to the interests of mathematical research and scholarship, and serves the national and international community through its publications, meetings, ...

. In 2012 Webster was elected a Fellow of the American Mathematical Society. In 1977 he proved a significant theorem on biholomorphic mappings between algebraic real hypersurfaces. Using his expertise on Chern-Moser invariants, he developed a theory that provides a complete set of invariants for nondegenerate real hypersurfaces under volume-preserving biholomorphic transformations. He used the

edge-of-the-wedge theorem In mathematics, Bogoliubov's edge-of-the-wedge theorem implies that holomorphic functions on two "wedges" with an "edge" in common are analytic continuations of each other provided they both give the same continuous function on the edge. It is us ...

to prove an extension theorem that generalized a 1974 theorem of

Charles Fefferman Charles Louis Fefferman (born April 18, 1949) is an American mathematician at Princeton University, where he is currently the Herbert E. Jones, Jr. '43 University Professor of Mathematics. He was awarded the Fields Medal in 1978 for his contribu ...

Selected publications

* * * with Klas Diederich: * with Jürgen K. Moser:

References

{{DEFAULTSORT:Webster, Sidney Martin 20th-century American mathematicians 21st-century American mathematicians University of California, Berkeley alumni University of Minnesota faculty University of Chicago faculty Complex analysts Fellows of the American Mathematical Society 1945 births Living people