David Bryant Mumford (born 11 June 1937) is an American mathematician known for distinguished work in algebraic geometry, and then for research into vision and pattern theory. He won the Fields Medal and was a 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.
Contents

Early life 1

Work in algebraic geometry 2

Work on pathologies in algebraic geometry 3

Characteristicp pathologies 3.1

Pathologies of moduli spaces 3.2

Classification of surfaces 4

Awards and honors 5

Current activity 6

See also 7

Notes 8

References 9

External links 10
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]}
In high school, he was a finalist in the prestigious Westinghouse Science Talent Search. After attending the Phillips Exeter Academy, Mumford went to Harvard, where he became a student of Oscar Zariski. At Harvard, he became a Putnam fellow in 1955 and 1956. He completed his Ph.D. in 1961, with a thesis entitled Existence of the moduli scheme for curves of any genus.
He met his first wife, Erika Jentsch, at Radcliffe College. After Erika died in 1988, he married his second wife, Jenifer Gordon.
He and Erika had four children. Steve (born 1960) is a published artist residing in New York City, Peter (born 1962) is a professional photographer and web developer living in Seattle, Jeremy (born 1969) is a historian, while Suchitra (born 1970, now Suchitra Baranoff) has worked for more than fifteen years in the field of international adoption.
Work in algebraic geometry
Mumford's work in geometry combined traditional geometric insights with the latest algebraic techniques. He published on moduli spaces, with a theory summed up in his book Geometric Invariant Theory, on the equations defining an abelian variety, and on algebraic surfaces.
His books Abelian Varieties (with C. P. Ramanujam) and Curves on an Algebraic Surface combined the old and new theories. His lecture notes on scheme theory circulated for years in unpublished form, at a time when they were, beside the treatise Éléments de géométrie algébrique, the only accessible introduction. They are now available as The Red Book of Varieties and Schemes (ISBN 354063293X).
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 wellbehaved 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.
Characteristicp pathologies
Mumford's philosophy in characteristic p was as follows:

"A nonsingular characteristic p variety is analogous to a general nonKähler 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 Enriques surfaces in characteristic two. This second example is developed further in Mumford's third paper on classification of surfaces in characteristic p (written in collaboration with E. Bombieri). This pathology can now be explained in terms of the Picard scheme of the surface, and in particular, its failure to be a reduced scheme, which is a theme developed in Mumford's book "Lectures on Curves on an Algebraic Surface". Worse pathologies related to ptorsion 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 geometric genus is nonzero, but the second Betti number is equal to the rank of the Néron–Severi group. Further such examples arise in Zariski surface theory. He also conjectures that the Kodaira vanishing theorem is false for surfaces in characteristic p. In the third paper, he gives an example of a 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 nonsingular curves.
These sorts of pathologies were considered to be fairly scarce when they first appeared. But recently, R. Vakil in a paper called "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 E. Bombieri), Mumford extended the Enriques–Kodaira classification of smooth projective surfaces from the case of the complex groundfield to the case of an algebraically closed groundfield of characteristic p. The final answer turns out to be essentially as the answer in the complex case (though the methods employed are sometimes quite different), once two important adjustments are made. The first is that one may get "nonclassical" surfaces, which come about when ptorsion in the Picard scheme degenerates to a nonreduced group scheme. The second is the possibility of obtaining quasielliptic 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 K3 surfaces, abelian surfaces, hyperelliptic and quasihyperelliptic surfaces, and Enriques surfaces. There are classical and nonclassical examples in the last two Kodaira dimension zero cases. c) Kodaira dimension 1. These are the elliptic and quasielliptic 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


Astronomy



Life science and medicine



Mathematical science



External links

Lectures on Curves on Algebraic Surfaces (with George Bergman), Princeton University Press, 1964.

Geometric Invariant Theory,SpringerVerlag, 1965 – 2nd edition, with J. Fogarty, 1982; 3rd enlarged edition, with F. Kirwan and J. Fogarty, 1994.

Mumford, David (1999) [1967], The red book of varieties and schemes, Lecture Notes in Mathematics 1358 (expanded, Includes Michigan Lectures (1974) on Curves and their Jacobians ed.), Berlin, New York:

Abelian Varieties, Oxford University Press, 1st edition 1970; 2nd edition 1974.

Six Appendices to Algebraic Surfaces by Oscar Zariski – 2nd edition, SpringerVerlag, 1971.

Toroidal Embeddings I (with G. Kempf, F. Knudsen and B. SaintDonat), Lecture Notes in Mathematics #339, SpringerVerlag 1973.

Curves and their Jacobians , University of Michigan Press, 1975.

Smooth Compactification of Locally Symmetric Varieties (with A. Ash, M. Rapoport and Y. Tai, Math. Sci. Press, 1975)

Algebraic Geometry I: Complex Projective Varieties , SpringerVerlag New York, 1975.

Tata Lectures on Theta (with C. Musili, M. Nori, P. Norman, E. Previato and M. Stillman), BirkhäuserBoston, Part I 1982, Part II 1983, Part III 1991.

Filtering, Segmentation and Depth (with M. Nitzberg and T. Shiota), Lecture Notes in Computer Science #662, 1993.

Two and Three Dimensional Pattern of the Face (with P. Giblin, G. Gordon, P. Hallinan and A. Yuille), AKPeters, 1999.

Indra's Pearls: The Vision of Felix Klein (with C. Series and D. Wright), Cambridge University Press, 2002.

Selected Papers on the Classification of Varieties and Moduli Spaces, SpringerVerlag, 2004.

Pattern Theory through Examples (with A. Desolneux, in preparation)
References

^ Mumford, David; Shah, Jayant (1989). "Optimal Approximations by Piecewise Smooth Functions and Associated Variational Problems". Comm. Pure Appl. Math. XLII: 577–685.

^ Fields Medallists' Lectures, World Scientific Series in 20th Century Mathematics, Vol 5. World Scientific. 1997. p. 225.

^ "U.S. prof. gives Israeli prize money to Palestinian university – Haaretz – Israel News".

^ Mumford, David (September 2008). "The Wolf Prize and Supporting Palestinian Education" (PDF). Notices of the American Mathematical Society (American Mathematical Society) 55 (8): 919.

^ "Mathematician David Mumford to receive National Medal of Science".

^ List of Fellows of the American Mathematical Society, retrieved 20130210.

^ "Gruppe 1: Matematiske fag" (in Norwegian).

^ http://www.browndailyherald.com/commencement2011honorarydegrees1.2579444
Notes
See also
His current area of work is pattern theory. In 2010, he published a book Pattern Theory: The Stochastic Analysis of RealWorld Signals with Agnès Desolneux.
In 2002, Mumford wrote a book with Caroline Series and David Wright on the visual geometry of limit sets: Indra's Pearls: The Vision of Felix Klein (ISBN 0521352533).
Current activity
He was elected President of the International Mathematical Union in 1995 and served from 1995 to 1999.
There is a long list of awards and honors besides the above, including
^{[6]}.American Mathematical Society In 2012 he became a fellow of the ^{[5]}.National Medal of Science In 2010 he was awarded the ^{[4]}[3]
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