Stephen Smale
Smale in 2008
Stephen Smale

(1930-07-15) July 15, 1930 (age 93)
EducationUniversity of Michigan (BS, PhD)
Known forGeneralized Poincaré conjecture
Handle decomposition
h-cobordism theorem
Homoclinic orbit
Horseshoe map
Smale conjecture
Smale's problems
Morse–Smale system
Morse–Smale diffeomorphism
Palais–Smale compactness condition
Blum–Shub–Smale machine
Smale–Williams attractor
Morse–Palais lemma
Regular homotopy
Sard's theorem
Sphere eversion
Structural stability
Whitehead torsion
AwardsWolf Prize (2007)
National Medal of Science (1996)
Chauvenet Prize (1988)[1]
Fields Medal (1966)
Oswald Veblen Prize in Geometry (1966)
Sloan Fellowship (1960)
Scientific career
InstitutionsToyota Technological Institute at Chicago
City University of Hong Kong
University of Chicago
Columbia University
University of California, Berkeley
ThesisRegular Curves on Riemannian Manifolds (1957)
Doctoral advisorRaoul Bott
Doctoral studentsRufus Bowen
César Camacho
Robert L. Devaney
John Guckenheimer
Morris Hirsch
Nancy Kopell
Jacob Palis
Themistocles M. Rassias
James Renegar
Siavash Shahshahani
Mike Shub

Stephen Smale (born July 15, 1930) is an American mathematician, known for his research in topology, dynamical systems and mathematical economics. He was awarded the Fields Medal in 1966[2] and spent more than three decades on the mathematics faculty of the University of California, Berkeley (1960–1961 and 1964–1995), where he currently is Professor Emeritus, with research interests in algorithms, numerical analysis and global analysis.[3]

Education and career

Smale was born in Flint, Michigan and entered the University of Michigan in 1948.[4][5] Initially, he was a good student, placing into an honors calculus sequence taught by Bob Thrall and earning himself A's. However, his sophomore and junior years were marred with mediocre grades, mostly Bs, Cs and even an F in nuclear physics. Smale obtained his Bachelor of Science degree in 1952. Despite his grades, with some luck, Smale was accepted as a graduate student at the University of Michigan's mathematics department. Yet again, Smale performed poorly in his first years, earning a C average as a graduate student. When the department chair, Hildebrandt, threatened to kick Smale out, he began to take his studies more seriously.[6] Smale finally earned his PhD in 1957, under Raoul Bott, beginning his career as an instructor at the University of Chicago.

Early in his career, Smale was involved in controversy over remarks he made regarding his work habits while proving the higher-dimensional Poincaré conjecture. He said that his best work had been done "on the beaches of Rio."[7][8] He has been politically active in various movements in the past, such as the Free Speech movement. In 1966, having travelled to Moscow under an NSF grant to accept the Fields Medal, he held a press conference there to denounce the American position in Vietnam, Soviet intervention in Hungary and Soviet maltreatment of intellectuals. After his return to the US, he was unable to renew the grant.[9] At one time he was subpoenaed[10] by the House Un-American Activities Committee.

In 1960, Smale received a Sloan Research Fellowship and was appointed to the Berkeley mathematics faculty, moving to a professorship at Columbia the following year. In 1964 he returned to a professorship at Berkeley, where he has spent the main part of his career. He became a professor emeritus at Berkeley in 1995 and took up a post as professor at the City University of Hong Kong. He also amassed over the years one of the finest private mineral collections in existence. Many of Smale's mineral specimens can be seen in the book The Smale Collection: Beauty in Natural Crystals.[11]

From 2003 to 2012, Smale was a professor at the Toyota Technological Institute at Chicago;[12] starting August 1, 2009, he became a Distinguished University Professor at the City University of Hong Kong.[13]

In 1988, Smale was the recipient of the Chauvenet Prize[1] of the MAA. In 2007, Smale was awarded the Wolf Prize in mathematics.[14]


Smale proved that the oriented diffeomorphism group of the two-dimensional sphere has the same homotopy type as the special orthogonal group of 3 × 3 matrices.[15] Smale's theorem has been reproved and extended a few times, notably to higher dimensions in the form of the Smale conjecture,[16] as well as to other topological types.[17]

In another early work, he studied the immersions of the two-dimensional sphere into Euclidean space.[18] By relating immersion theory to the algebraic topology of Stiefel manifolds, he was able to fully clarify when two immersions can be deformed into one another through a family of immersions. Directly from his results it followed that the standard immersion of the sphere into three-dimensional space can be deformed (through immersions) into its negation, which is now known as sphere eversion. He also extended his results to higher-dimensional spheres,[19] and his doctoral student Morris Hirsch extended his work to immersions of general smooth manifolds.[20] Along with John Nash's work on isometric immersions, the Hirsch–Smale immersion theory was highly influential in Mikhael Gromov's early work on development of the h-principle, which abstracted and applied their ideas to contexts other than that of immersions.[21]

In the study of dynamical systems, Smale introduced what is now known as a Morse–Smale system.[22] For these dynamical systems, Smale was able to prove Morse inequalities relating the cohomology of the underlying space to the dimensions of the (un)stable manifolds. Part of the significance of these results is from Smale's theorem asserting that the gradient flow of any Morse function can be arbitrarily well approximated by a Morse–Smale system without closed orbits.[23] Using these tools, Smale was able to construct self-indexing Morse functions, where the value of the function equals its Morse index at any critical point.[24] Using these self-indexing Morse functions as a key tool, Smale resolved the generalized Poincaré conjecture in every dimension greater than four.[25] Building on these works, he also established the more powerful h-cobordism theorem the following year, together with the full classification of simply-connected smooth five-dimensional manifolds.[26][24]

Smale also introduced the horseshoe map, inspiring much subsequent research. He also outlined a research program carried out by many others. Smale is also known for injecting Morse theory into mathematical economics, as well as recent explorations of various theories of computation.

In 1998 he compiled a list of 18 problems in mathematics to be solved in the 21st century, known as Smale's problems.[27] This list was compiled in the spirit of Hilbert's famous list of problems produced in 1900. In fact, Smale's list contains some of the original Hilbert problems, including the Riemann hypothesis and the second half of Hilbert's sixteenth problem, both of which are still unsolved. Other famous problems on his list include the Poincaré conjecture (now a theorem, proved by Grigori Perelman), the P = NP problem, and the Navier–Stokes equations, all of which have been designated Millennium Prize Problems by the Clay Mathematics Institute.


Important publications

See also


  1. ^ a b Smale, Steve (1985). "On the Efficiency of Algorithms in Analysis". Bulletin of the American Mathematical Society. New Series. 13 (2): 87–121. doi:10.1090/S0273-0979-1985-15391-1.
  2. ^ "How Math Got Its 'Nobel'". The New York Times. 8 August 2014. Retrieved 21 October 2016.
  3. ^ "Stephen Smale". University of California, Berkeley. Retrieved 27 November 2021.
  4. ^ William L. Hosch, ed. (2010). The Britannica Guide to Geometry. Britannica Educational Publishing. p. 225. ISBN 9781615302178.
  5. ^ Batterson, Steve (2000). Steven Smale: The Mathematician Who Broke the Dimension Barrier. American Mathematical Soc. p. 11. ISBN 9780821826966.
  6. ^ Video on YouTube
  7. ^ He discovered the famous Smale horseshoe map on a beach in Leme, Rio de Janeiro. See: S. Smale (1996), Chaos: Finding a Horseshoe on the Beaches of Rio.
  8. ^ CS Aravinda (2018). "ICM 2018: On the beaches of Rio de Janeiro". Bhāvanā. 2 (3). Retrieved 8 October 2022.
  9. ^ Andrew Jamison (5 October 1967). "Math Professors Question Denial Of Smale Grant". The Harvard Crimson. Retrieved 13 February 2022.
  10. ^ Greenberg, D. S. (1966-10-07). "The Smale Case: NSF and Berkeley Pass Through a Case of Jitters". Science. 154 (3745). American Association for the Advancement of Science (AAAS): 130–133. Bibcode:1966Sci...154..130G. doi:10.1126/science.154.3745.130. ISSN 0036-8075. PMID 17740098.
  11. ^ "Lithographie LTD".
  12. ^ "Faculty Alumni".
  13. ^ Stephen Smale Vita. Accessed November 18, 2009.
  14. ^ "The Hebrew University of Jerusalem - Division of Marketing & Communication". Archived from the original on 2016-03-03. Retrieved 2007-02-04.
  15. ^ Smale 1959c.
  16. ^ Hatcher, Allen E. (1983). "A proof of the Smale conjecture, Diff(S3) ≃ O(4)". Annals of Mathematics. Second Series. 117 (3): 553–607. doi:10.2307/2007035. JSTOR 2007035. MR 0701256. Zbl 0531.57028.
  17. ^ Earle, Clifford J.; Eells, James (1969). "A fibre bundle description of Teichmüller theory". Journal of Differential Geometry. 3 (1–2): 19–43. doi:10.4310/jdg/1214428816. MR 0276999. Zbl 0185.32901.
  18. ^ Smale 1959a.
  19. ^ Smale 1959b.
  20. ^ Hirsch, Morris W. (1959). "Immersions of manifolds". Transactions of the American Mathematical Society. 93 (2): 242–276. doi:10.1090/S0002-9947-1959-0119214-4. MR 0119214. Zbl 0113.17202.
  21. ^ Gromov, Mikhael (1986). Partial differential relations. Ergebnisse der Mathematik und ihrer Grenzgebiete, 3. Folge. Vol. 9. Berlin: Springer-Verlag. doi:10.1007/978-3-662-02267-2. ISBN 3-540-12177-3. MR 0864505. Zbl 0651.53001.
  22. ^ Smale 1960.
  23. ^ Smale 1961a.
  24. ^ a b Milnor, John (1965). Lectures on the h-cobordism theorem. Notes by L. Siebenmann and J. Sondow. Princeton, NJ: Princeton University Press. doi:10.1515/9781400878055. ISBN 9781400878055. MR 0190942. Zbl 0161.20302.
  25. ^ Smale 1961b.
  26. ^ Smale 1962a; Smale 1962b.
  27. ^ Smale 1998; Smale 2000.
Personal websites at universities