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Stephen Smale
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 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. Education and career Smale was born in Flint, Michigan and entered the University of Michigan in 1948. 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. However, 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 g ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Flint, Michigan
Flint is the largest city and seat of Genesee County, Michigan, United States. Located along the Flint River, northwest of Detroit, it is a principal city within the region known as Mid Michigan. At the 2020 census, Flint had a population of 81,252, making it the twelfth largest city in Michigan. The Flint metropolitan area is located entirely within Genesee County. It is the fourth largest metropolitan area in Michigan with a population of 406,892 in 2020. The city was incorporated in 1855. Flint was founded as a village by fur trader Jacob Smith in 1819 and became a major lumbering area on the historic Saginaw Trail during the 19th century. From the late 19th century to the mid 20th century, the city was a leading manufacturer of carriages and later automobiles, earning it the nickname "Vehicle City". General Motors (GM) was founded in Flint in 1908, and the city grew into an automobile manufacturing powerhouse for GM's Buick and Chevrolet divisions, especially after Wo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Themistocles M
Themistocles (; grc-gre, Θεμιστοκλῆς; c. 524–459 BC) was an Athenian politician and general. He was one of a new breed of non-aristocratic politicians who rose to prominence in the early years of the Athenian democracy. As a politician, Themistocles was a populist, having the support of lower-class Athenians, and generally being at odds with the Athenian nobility. Elected archon in 493 BC, he convinced the polis to increase the naval power of Athens, a recurring theme in his political career. During the first Persian invasion of Greece he fought at the Battle of Marathon (490 BC) and was possibly one of the ten Athenian ''strategoi'' (generals) in that battle. In the years after Marathon, and in the run-up to the second Persian invasion of 480–479 BC, Themistocles became the most prominent politician in Athens. He continued to advocate for a strong Athenian Navy, and in 483 BC he persuaded the Athenians to build a fleet of 200 triremes; these proved ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Palais–Smale Compactness Condition
The Palais–Smale compactness condition, named after Richard Palais and Stephen Smale, is a hypothesis for some theorems of the calculus of variations. It is useful for guaranteeing the existence of certain kinds of critical point (mathematics), critical points, in particular saddle points. The Palais-Smale condition is a condition on the functional (mathematics), functional that one is trying to extremize. In finite-dimensional spaces, the Palais–Smale condition for a continuously differentiable real-valued function is satisfied automatically for proper maps: functions which do not take unbounded sets into bounded sets. In the calculus of variations, where one is typically interested in infinite-dimensional function spaces, the condition is necessary because some extra notion of compactness beyond simple boundedness is needed. See, for example, the proof of the mountain pass theorem in section 8.5 of Evans. Strong formulation A continuously Fréchet derivative, Fréchet ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Morse–Smale Diffeomorphism
In mathematics, Smale's axiom A defines a class of dynamical systems which have been extensively studied and whose dynamics is relatively well understood. A prominent example is the Smale horseshoe map. The term "axiom A" originates with Stephen Smale.Ruelle (1978) p.149 The importance of such systems is demonstrated by the chaotic hypothesis, which states that, 'for all practical purposes', a many-body thermostatted system is approximated by an Anosov system. Definition Let ''M'' be a smooth manifold with a diffeomorphism ''f'': ''M''→''M''. Then ''f'' is an axiom A diffeomorphism if the following two conditions hold: #The nonwandering set of ''f'', ''Ω''(''f''), is a hyperbolic set and compact. #The set of periodic points of ''f'' is dense in ''Ω''(''f''). For surfaces, hyperbolicity of the nonwandering set implies the density of periodic points, but this is no longer true in higher dimensions. Nonetheless, axiom A diffeomorphisms are sometimes called hyper ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Smale's Problems
Smale's problems are a list of eighteen unsolved problems in mathematics proposed by Steve Smale in 1998 and republished in 1999. Smale composed this list in reply to a request from Vladimir Arnold, then vice-president of the International Mathematical Union, who asked several mathematicians to propose a list of problems for the 21st century. Arnold's inspiration came from the list of Hilbert's problems that had been published at the beginning of the 20th century. Table of problems In later versions, Smale also listed three additional problems, "that don't seem important enough to merit a place on our main list, but it would still be nice to solve them:" # Mean value problem #Is the three-sphere a minimal set ( Gottschalk's conjecture)? #Is an Anosov diffeomorphism of a compact manifold topologically the same as the Lie group model of John Franks? See also * Millennium Prize Problems * Simon problems In mathematics, the Simon problems (or Simon's problems) are a series ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Smale Conjecture
The Smale conjecture, named after Stephen Smale, is the statement that the diffeomorphism group of the 3-sphere has the homotopy-type of its isometry group, the orthogonal group O(4). It was proved in 1983 by Allen Hatcher. Equivalent statements There are several equivalent statements of the Smale conjecture. One is that the component of the unknot in the space of smooth embeddings of the circle in 3-space has the homotopy-type of the round circles, equivalently, O(3). Interestingly, this statement is not equivalent to the generalized Smale Conjecture, in higher dimensions. Another equivalent statement is that the group of diffeomorphisms of the 3-ball which restrict to the identity on the boundary is contractible. Yet another equivalent statement is that the space of constant-curvature Riemann metrics on the 3-sphere is contractible. Higher dimensions The (false) statement that the inclusion O(n+1) \to \text(S^n) is a weak equivalence for all n is sometimes meant whe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Smale's Theorem
In geometric topology and differential topology, an (''n'' + 1)-dimensional cobordism ''W'' between ''n''-dimensional manifolds ''M'' and ''N'' is an ''h''-cobordism (the ''h'' stands for homotopy equivalence) if the inclusion maps : M \hookrightarrow W \quad\mbox\quad N \hookrightarrow W are homotopy equivalences. The ''h''-cobordism theorem gives sufficient conditions for an ''h''-cobordism to be trivial, i.e., to be C-isomorphic to the cylinder ''M'' × , 1 Here C refers to any of the categories of smooth, piecewise linear, or topological manifolds. The theorem was first proved by Stephen Smale for which he received the Fields Medal and is a fundamental result in the theory of high-dimensional manifolds. For a start, it almost immediately proves the generalized Poincaré conjecture. Background Before Smale proved this theorem, mathematicians became stuck while trying to understand manifolds of dimension 3 or 4, and assumed that the higher-dimensional cases were ev ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Homoclinic Orbit
In mathematics, a homoclinic orbit is a trajectory of a flow of a dynamical system which joins a saddle equilibrium point to itself. More precisely, a homoclinic orbit lies in the intersection of the stable manifold and the unstable manifold of an equilibrium. Consider the continuous dynamical system described by the ODE :\dot x=f(x) Suppose there is an equilibrium at x=x_0, then a solution \Phi(t) is a homoclinic orbit if :\Phi(t)\rightarrow x_0\quad \mathrm\quad t\rightarrow\pm\infty If the phase space has three or more dimensions, then it is important to consider the topology of the unstable manifold of the saddle point. The figures show two cases. First, when the stable manifold is topologically a cylinder, and secondly, when the unstable manifold is topologically a Möbius strip; in this case the homoclinic orbit is called ''twisted''. Discrete dynamical system Homoclinic orbits and homoclinic points are defined in the same way for iterated functions, as the int ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Handle Decomposition
In mathematics, a handle decomposition of an ''m''-manifold ''M'' is a union \emptyset = M_ \subset M_0 \subset M_1 \subset M_2 \subset \dots \subset M_ \subset M_m = M where each M_i is obtained from M_ by the attaching of i-handles. A handle decomposition is to a manifold what a CW complex, CW-decomposition is to a topological space—in many regards the purpose of a handle decomposition is to have a language analogous to CW-complexes, but adapted to the world of smooth manifolds. Thus an ''i''-handle is the smooth analogue of an ''i''-cell. Handle decompositions of manifolds arise naturally via Morse theory. The modification of handle structures is closely linked to Cerf theory. Motivation Consider the standard CW-complex, CW-decomposition of the ''n''-sphere, with one zero cell and a single ''n''-cell. From the point of view of smooth manifolds, this is a degenerate decomposition of the sphere, as there is no natural way to see the smooth structure of S^n from the eyes of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Generalized Poincaré Conjecture
In the mathematical area of topology, the generalized Poincaré conjecture is a statement that a manifold which is a homotopy sphere a sphere. More precisely, one fixes a category of manifolds: topological (Top), piecewise linear (PL), or differentiable (Diff). Then the statement is :Every homotopy sphere (a closed ''n''-manifold which is homotopy equivalent to the ''n''-sphere) in the chosen category (i.e. topological manifolds, PL manifolds, or smooth manifolds) is isomorphic in the chosen category (i.e. homeomorphic, PL-isomorphic, or diffeomorphic) to the standard ''n''-sphere. The name derives from the Poincaré conjecture, which was made for (topological or PL) manifolds of dimension 3, where being a homotopy sphere is equivalent to being simply connected and closed. The generalized Poincaré conjecture is known to be true or false in a number of instances, due to the work of many distinguished topologists, including the Fields medal awardees John Milnor, Steve Smale, Micha ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
