David Mumford

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David Mumford

David Bryant Mumford (born 11 June 1937) is an American

MacArthur Fellow. In 2010 he was awarded the National Medal of Science. He is currently a University Professor Emeritus in the Division of Applied Mathematics at Brown University
.

Early life

Mumford was born in Worth, West Sussex in England, of an English father and American mother. His father William started an experimental school in Tanzania and worked for the then newly created United Nations.[2]

He attended

PhD
in 1961, with a thesis entitled Existence of the moduli scheme for curves of any genus. He married Erika, an author and poet, in 1959 and they had four children, Stephen, Peter, Jeremy, and Suchitra. He currently has seven grandchildren.

Work in algebraic geometry

Mumford's work in geometry combined traditional geometric insights with the latest algebraic techniques. He published on

Geometric Invariant Theory, on the equations defining an abelian variety, and on algebraic surfaces
.

His books Abelian Varieties (with

).

Other work that was less thoroughly written up were lectures on varieties defined by quadrics, and a study of Goro Shimura's papers from the 1960s.

Mumford's research did much to revive the classical theory of theta functions, by showing that its algebraic content was large, and enough to support the main parts of the theory by reference to finite analogues of the Heisenberg group. This work on the equations defining abelian varieties appeared in 1966–7. He published some further books of lectures on the theory.

He also was one of the founders of the

toroidal embedding theory; and sought to apply the theory to Gröbner basis
techniques, through students who worked in algebraic computation.

Work on pathologies in algebraic geometry

In a sequence of four papers published in the American Journal of Mathematics between 1961 and 1975, Mumford explored pathological behavior in algebraic geometry, that is, phenomena that would not arise if the world of algebraic geometry were as well-behaved as one might expect from looking at the simplest examples. These pathologies fall into two types: (a) bad behavior in characteristic p and (b) bad behavior in moduli spaces.

Characteristic-p pathologies

Mumford's philosophy in characteristic p was as follows:

A nonsingular characteristic p variety is analogous to a general non-Kähler complex manifold; in particular, a projective embedding of such a variety is not as strong as a

Kähler metric on a complex manifold, and the Hodge–Lefschetz–Dolbeault theorems on sheaf cohomology
break down in every possible way.

In the first Pathologies paper, Mumford finds an everywhere regular differential form on a smooth projective surface that is not closed, and shows that Hodge symmetry fails for classical

reduced scheme, which is a theme developed in Mumford's book "Lectures on Curves on an Algebraic Surface". Worse pathologies related to p-torsion in crystalline cohomology were explored by Luc Illusie
(Ann. Sci. Ec. Norm. Sup. (4) 12 (1979), 501–661).

In the second Pathologies paper, Mumford gives a simple example of a surface in characteristic p where the

normal surface for which Kodaira vanishing fails. The first example of a smooth surface for which Kodaira vanishing fails was given by Michel Raynaud
in 1978.

Pathologies of moduli spaces

In the second Pathologies paper, Mumford finds that the Hilbert scheme parametrizing space curves of degree 14 and genus 24 has a multiple component. In the fourth Pathologies paper, he finds reduced and irreducible complete curves which are not specializations of non-singular curves.

These sorts of pathologies were considered to be fairly scarce when they first appeared. But Ravi Vakil showed in his paper "Murphy's law in algebraic geometry" has shown that Hilbert schemes of nice geometric objects can be arbitrarily "bad", with unlimited numbers of components and with arbitrarily large multiplicities (Invent. Math. 164 (2006), 569–590).

Classification of surfaces

In three papers written between 1969 and 1976 (the last two in collaboration with

quasi-elliptic surfaces in characteristics two and three. These are surfaces fibred over a curve where the general fibre is a curve of arithmetic genus
one with a cusp.

Once these adjustments are made, the surfaces are divided into four classes by their Kodaira dimension, as in the complex case. The four classes are: a) Kodaira dimension minus infinity. These are the ruled surfaces. b) Kodaira dimension 0. These are the

quasi-hyperelliptic surfaces, and Enriques surfaces
. There are classical and non-classical examples in the last two Kodaira dimension zero cases. c) Kodaira dimension 1. These are the elliptic and
quasi-elliptic surfaces
not contained in the last two groups. d) Kodaira dimension 2. These are the
surfaces of general type
.

Awards and honors

David Mumford in 1975

Mumford was awarded a

Fields Medal
in 1974. He was a
Steele Prize for Mathematical Exposition by the American Mathematical Society. In 2008 he was awarded the Wolf Prize; on receiving the prize in Jerusalem from Shimon Peres, Mumford announced that he was donating half of the prize money to Birzeit University in the Palestinian territories and half to Gisha, an Israeli organization that promotes the right to freedom of movement of Palestinians in the Gaza Strip.[6][7] He also served on the Mathematical Sciences jury for the Infosys Prize in 2009 and 2010. In 2010 he was awarded the National Medal of Science.[8] In 2012 he became a fellow of the American Mathematical Society.[9]

There is a long list of awards and honors besides the above, including

He was elected President of the International Mathematical Union in 1995 and served from 1995 to 1999.

See also

Notes

  1. .
  2. .
  3. ^ "Autobiography of David Mumford", The Shaw Prize, 2006
  4. ^ David B. Mumford, "How a Computer Works", Radio-Electronics, February 1955, p. 58, 59, 60
  5. ^ "Putnam Competition Individual and Team Winners". Mathematical Association of America. Retrieved 10 December 2021.
  6. ^ "U.S. prof. gives Israeli prize money to Palestinian university – Haaretz – Israel News". Haaretz. 26 May 2008. Retrieved 26 May 2008.
  7. ISSN 0002-9920
    .
  8. ^ "Mathematician David Mumford to receive National Medal of Science". Brown University. 15 October 2010. Retrieved 25 October 2010.
  9. ^ List of Fellows of the American Mathematical Society, retrieved 2013-02-10.
  10. ^ "APS Member History". search.amphilsoc.org. Retrieved 8 December 2021.
  11. ^ NTNU's list of honorary doctors
  12. ^ "Gruppe 1: Matematiske fag" (in Norwegian). Norwegian Academy of Science and Letters. Archived from the original on 10 November 2013. Retrieved 7 October 2010.
  13. ^ "Commencement 2011: Honorary degrees". 29 May 2011. Archived from the original on 15 March 2012. Retrieved 29 May 2011.

Publications

External links