1 Prolog
Convexity stems from the remote ages
and reigns in geometry, optimization, and functional analysis.
The union of abstraction and convexity has produced
abstract convexity which is a vast area of today’s research,
sometimes profitable but sometimes bizarre.
The idea of convexity feeds generation, separation, calculus,
and approximation. Generation appears as duality; separation, as optimality;
calculus, as representation; and approximation, as stability.
This talk is an overview of the origin, evolution,
and basics of convexity, primarily emphasizing the
rules of subdifferential calculus.
2 Origins of Convexity
2.1 Euclid’s Elements and Convexity
2.2 Harpedonaptae and Sulva Sutras
2.3 Enter Abstract Convexity
2.4 Mathesis and Abstraction
3 Convexity and Optimization
3.1 Minkowski Duality
3.2 Enter the Reals
3.3 Legendre in Disguise
3.4 Order Omnipresent
3.5 Fermat’s Criterion
4 Subdifferential Calculus
4.1 Enter Hahn–Banach
4.2 Enter Kantorovich
4.3 Ioffe’s Fans
4.4 Canonical Operator
4.5 Support Hull
4.6 Hahn–Banach in Disguise
5 Boolean Methods in Convexity
5.1 Enter Boole
5.2 Enter Descent
5.3 The Reals in Disguise
5.4 Approximation
5.5 Enter Epsilon and Monad
5.6 Subdifferential Halo
5.7 Exeunt Epsilon
6 Epilog
Abstract convexity starts with repudiating the heritage of harpedonaptae,
which is annoying and vexing but may turn out rewarding.
Freedom of set theory empowered us with the Boolean-valued models
yielding
a lot of surprising and unforeseen visualizations
of the continuum. Many promising
opportunities are open to modeling the powerful habits of
reasoning and verification.
Convexity is a topical
illustration of the wisdom and strength of mathematics, the ever fresh
art and science of calculus.
References
-
[1]
Heaves Th. (1956)
The Thirteen Books of Euclid’s Elements. Vol. 1–3.
New York: Dover Publications.
-
[2]
Kak S. C. (1997)
Science in Ancient India.
In: Sridhar S. R. and Mattoo N. K. (eds.)
Ananya: A Portrait of India.
New York: AIA, 399–420.
-
[3]
Kutateladze S. S. and Rubinov A. M. (1972)
Minkowski duality and its applications.
Russian Math. Surveys, 27:3, 137–191.
-
[4]
Kutateladze S. S. and Rubinov A. M. (1976)
Minkowski Duality and Its Applications.
Novosibirsk: Nauka Publishers [in Russian].
-
[5]
Fuchssteiner B. and Lusky W. (1981)
Convex Cones. Amsterdam: North-Holland.
-
[6]
Hörmander L. (1994)
Notions of Convexity. Boston: Birkhäuser.
-
[7]
Singer I. (1997)
Abstract Convex Analysis.
New York: John Wiley & Sons.
-
[8]
Pallaschke D. and Rolewicz S. (1998)
Foundations of Mathematical Optimization, Convex
Analysis Without Linearity. Dordrecht: Kluwer Academic Publishers.
-
[9]
Rubinov A. M. (2000)
Abstract Convexity and Global Optimization. Dordrecht:
Kluwer Academic Publishers.
-
[10]
Ioffe A. D. and Rubinov A. M. (2002)
Abstract convexity and nonsmooth analysis. Global aspects.
Adv. Math. Econom., 4, 1–23.
-
[11]
Fenchel W. (1953)
Convex Cones, Sets, and Functions.
Princeton: Princeton Univ. Press.
-
[12]
Kusraev A. G. and Kutateladze S. S. (2005)
Introduction to Boolean-Valued Analysis.
Moscow: Nauka Publishers [in Russian].
-
[13]
Dilworth S. J., Howard R., and Roberts J. W. (2006)
A general theory of almost convex functions.
Trans. Amer. Math. Soc.,
358:8, 3413–3445.
-
[14]
Kusraev A. G. and Kutateladze S. S. (2007)
Subdifferential Calculus: Theory and Applications.
Moscow: Nauka Publishers [in Russian].
This is an abstract of a talk prepared for the
Conference on Nonlinear Analysis and Optimization, Technion (Haifa, Israel),
June 18–24, 2008,
in celebration of Alex Ioffe’s 70th and
Simeon Reich’s 60th birthdays. The talk was undelivered
due to illness.