|
Hadamard Space
In geometry, an Hadamard space, named after Jacques Hadamard, is a non-linear generalization of a Hilbert space. In the literature they are also equivalently defined as complete CAT(0) spaces. A Hadamard space is defined to be a nonempty complete metric space such that, given any points x and y, there exists a point m such that for every point z, d(z, m)^2 + \leq . The point m is then the midpoint of x and y: d(x, m) = d(y, m) = d(x, y)/2. In a Hilbert space, the above inequality is equality (with m = (x+y)/2), and in general an Hadamard space is said to be if the above inequality is equality. A flat Hadamard space is isomorphic to a closed convex subset of a Hilbert space. In particular, a normed space is an Hadamard space if and only if it is a Hilbert space. The geometry of Hadamard spaces resembles that of Hilbert spaces, making it a natural setting for the study of rigidity theorems. In a Hadamard space, any two points can be joined by a unique geodesic between them; in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
End Of Universe
End, END, Ending, or variation, may refer to: End *In mathematics: ** End (category theory) ** End (topology) ** End (graph theory) ** End (group theory) (a subcase of the previous) ** End (endomorphism) *In sports and games **End (gridiron football) **End, a division of play in the sports of curling, target archery and pétanque ** End (dominoes), one of the halves of the face of a domino tile *In entertainment: ** End (band) an American hardcore punk supergroup formed in 2017. ** End key on a modern computer keyboard ** End Records, a record label **"End", a song by The Cure from '' Wish'' ** Ends (song) (1998 song) song by Everlast, off the album '' Whitey Ford Sings the Blues'' *In other areas: **End, in weaving, a single thread of the warp **''Ends (short story collection)'' (1988 book) anthology of Gordon R. Dickson stories END * European Nuclear Disarmament * Endoglin, a glycoprotein * Equivalent narcotic depth, a concept used in underwater diving * Environmental ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Metric Tree
A metric tree is any tree data structure specialized to index data in metric spaces. Metric trees exploit properties of metric spaces such as the triangle inequality to make accesses to the data more efficient. Examples include the M-tree, vp-trees, cover trees, MVP trees, and BK-trees. Multidimensional search Most algorithms and data structures for searching a dataset are based on the classical binary search algorithm, and generalizations such as the k-d tree or range tree work by interleaving the binary search algorithm over the separate coordinates and treating each spatial coordinate as an independent search constraint. These data structures are well-suited for range query problems asking for every point (x,y) that satisfies \mbox_x \leq x \leq \mbox_x and \mbox_y \leq y \leq \mbox_y. A limitation of these multidimensional search structures is that they are only defined for searching over objects that can be treated as vectors. They aren't applicable for the more general ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Functional Analysis
Functional analysis is a branch of mathematical analysis, the core of which is formed by the study of vector spaces endowed with some kind of limit-related structure (e.g. inner product, norm, topology, etc.) and the linear functions defined on these spaces and respecting these structures in a suitable sense. The historical roots of functional analysis lie in the study of spaces of functions and the formulation of properties of transformations of functions such as the Fourier transform as transformations defining continuous, unitary etc. operators between function spaces. This point of view turned out to be particularly useful for the study of differential and integral equations. The usage of the word '' functional'' as a noun goes back to the calculus of variations, implying a function whose argument is a function. The term was first used in Hadamard's 1910 book on that subject. However, the general concept of a functional had previously been introduced in 1887 by the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Jacob Lurie
Jacob Alexander Lurie (born December 7, 1977) is an American mathematician who is a professor at the Institute for Advanced Study. Lurie is a 2014 MacArthur Fellow. Life When he was a student in the Science, Mathematics, and Computer Science Magnet Program at Montgomery Blair High School, Lurie took part in the International Mathematical Olympiad, where he won a gold medal with a perfect score in 1994. In 1996 he took first place in the Westinghouse Science Talent Search and was featured in a front-page story in the ''Washington Times''. Lurie earned his bachelor's degree in mathematics from Harvard College in 2000 and was awarded in the same year the Morgan Prize for his undergraduate thesis on Lie algebras. He earned his Ph.D. from the Massachusetts Institute of Technology under supervision of Michael J. Hopkins, in 2004 with a thesis on derived algebraic geometry. In 2007, he became associate professor at MIT, and in 2009 he became professor at Harvard University. I ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
European Mathematical Society
The European Mathematical Society (EMS) is a European organization dedicated to the development of mathematics in Europe. Its members are different mathematical societies in Europe, academic institutions and individual mathematicians. The current president is Volker Mehrmann, professor at the Institute for Mathematics at the Technical University of Berlin. Goals The Society seeks to serve all kinds of mathematicians in universities, research institutes and other forms of higher education. Its aims are to #Promote mathematical research, both pure and applied, #Assist and advise on problems of mathematical education, #Concern itself with the broader relations of mathematics to society, #Foster interaction between mathematicians of different countries, #Establish a sense of identity amongst European mathematicians, #Represent the mathematical community in supra-national institutions. The EMS is itself an Affiliate Member of the International Mathematical Union and an Associate Membe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dynamical System
In mathematics, a dynamical system is a system in which a function describes the time dependence of a point in an ambient space. Examples include the mathematical models that describe the swinging of a clock pendulum, the flow of water in a pipe, the random motion of particles in the air, and the number of fish each springtime in a lake. The most general definition unifies several concepts in mathematics such as ordinary differential equations and ergodic theory by allowing different choices of the space and how time is measured. Time can be measured by integers, by real or complex numbers or can be a more general algebraic object, losing the memory of its physical origin, and the space may be a manifold or simply a set, without the need of a smooth space-time structure defined on it. At any given time, a dynamical system has a state representing a point in an appropriate state space. This state is often given by a tuple of real numbers or by a vector in a geome ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dynamical Billiards
A dynamical billiard is a dynamical system in which a particle alternates between free motion (typically as a straight line) and specular reflections from a boundary. When the particle hits the boundary it reflects from it without loss of speed (i.e. elastic collisions). Billiards are Hamiltonian idealizations of the game of billiards, but where the region contained by the boundary can have shapes other than rectangular and even be multidimensional. Dynamical billiards may also be studied on non-Euclidean geometries; indeed, the first studies of billiards established their ergodic motion on surfaces of constant negative curvature. The study of billiards which are kept out of a region, rather than being kept in a region, is known as outer billiard theory. The motion of the particle in the billiard is a straight line, with constant energy, between reflections with the boundary (a geodesic if the Riemannian metric of the billiard table is not flat). All reflections are ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Serge Ferleger
{{disambiguation ...
Serge may refer to: * Serge (fabric), a type of twill fabric * Serge (llama) (born 2005), a llama in the Cirque Franco-Italien and internet meme * Serge (name), a masculine given name (includes a list of people with this name) * Serge (post), a hitching post used among the Buryats and Yakuts * Serge synthesizer, a modular synthesizer See also * Overlock, a type of stitch known as "serger" in North America * Surge (other) *Serg (other) Serg may refer to: *Van Serg (crater), a lunar crater named for a pseudonym *''Serg.'', taxonomic author abbreviation of Lidia Palladievna Sergievskaya (1897–1970), Soviet botanist, professor, and herbarium curator *Serg., abbreviation for Serge ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dmitri Burago
Dmitri Yurievich Burago (Дмитрий Юрьевич Бураго, born 1964) is a Russian mathematician, specializing in geometry. He is the son of the professor of mathematics in Leningrad Yuri Dmitrievich Burago, with whom he also published a book. Burago studied at 45th Physics-Mathematics School. Burago received his doctorate in 1994 at Saint Petersburg State University under the supervision of Anatoly Vershik. He was at the Steklov Institute in Saint Petersburg and is now a professor at Pennsylvania State University's Center for Dynamical Systems and Geometry. In 1992 he was awarded the prize of the Saint Petersburg Mathematical Society. In 1998 he was an Invited Speaker at the International Congress of Mathematicians in Berlin. In 2014 he was awarded the Leroy P. Steele Prize with Yuri Burago and Sergei Vladimirovich Ivanov for their book ''A course in metric geometry''. Selected publications Articles * "Periodic metrics." In: ''Seminar on dynamical systems'', pp. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Symmetric Space
In mathematics, a symmetric space is a Riemannian manifold (or more generally, a pseudo-Riemannian manifold) whose group of symmetries contains an inversion symmetry about every point. This can be studied with the tools of Riemannian geometry, leading to consequences in the theory of holonomy; or algebraically through Lie theory, which allowed Cartan to give a complete classification. Symmetric spaces commonly occur in differential geometry, representation theory and harmonic analysis. In geometric terms, a complete, simply connected Riemannian manifold is a symmetric space if and only if its curvature tensor is invariant under parallel transport. More generally, a Riemannian manifold (''M'', ''g'') is said to be symmetric if and only if, for each point ''p'' of ''M'', there exists an isometry of ''M'' fixing ''p'' and acting on the tangent space T_pM as minus the identity (every symmetric space is complete, since any geodesic can be extended indefinitely via symmetries ab ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sectional Curvature
In Riemannian geometry, the sectional curvature is one of the ways to describe the curvature of Riemannian manifolds. The sectional curvature ''K''(σ''p'') depends on a two-dimensional linear subspace σ''p'' of the tangent space at a point ''p'' of the manifold. It can be defined geometrically as the Gaussian curvature of the surface which has the plane σ''p'' as a tangent plane at ''p'', obtained from geodesics which start at ''p'' in the directions of σ''p'' (in other words, the image of σ''p'' under the exponential map at ''p''). The sectional curvature is a real-valued function on the 2-Grassmannian bundle over the manifold. The sectional curvature determines the curvature tensor completely. Definition Given a Riemannian manifold and two linearly independent tangent vectors at the same point, ''u'' and ''v'', we can define :K(u,v)= Here ''R'' is the Riemann curvature tensor, defined here by the convention R(u,v)w=\nabla_u\nabla_vw-\nabla_v\nabla ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Riemannian Manifold
In differential geometry, a Riemannian manifold or Riemannian space , so called after the German mathematician Bernhard Riemann, is a real, smooth manifold ''M'' equipped with a positive-definite inner product ''g''''p'' on the tangent space ''T''''p''''M'' at each point ''p''. The family ''g''''p'' of inner products is called a Riemannian metric (or Riemannian metric tensor). Riemannian geometry is the study of Riemannian manifolds. A common convention is to take ''g'' to be smooth, which means that for any smooth coordinate chart on ''M'', the ''n''2 functions :g\left(\frac,\frac\right):U\to\mathbb are smooth functions. These functions are commonly designated as g_. With further restrictions on the g_, one could also consider Lipschitz Riemannian metrics or measurable Riemannian metrics, among many other possibilities. A Riemannian metric (tensor) makes it possible to define several geometric notions on a Riemannian manifold, such as angle at an intersection, le ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
