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Geometric Measure Theory
In mathematics, geometric measure theory (GMT) is the study of geometric properties of sets (typically in Euclidean space) through measure theory. It allows mathematicians to extend tools from differential geometry to a much larger class of surfaces that are not necessarily smooth. History Geometric measure theory was born out of the desire to solve Plateau's problem (named after Joseph Plateau) which asks if for every smooth closed curve in \mathbb^3 there exists a surface of least area among all surfaces whose boundary equals the given curve. Such surfaces mimic soap films. The problem had remained open since it was posed in 1760 by Lagrange. It was solved independently in the 1930s by Jesse Douglas and Tibor Radó under certain topological restrictions. In 1960 Herbert Federer and Wendell Fleming used the theory of currents with which they were able to solve the orientable Plateau's problem analytically without topological restrictions, thus sparking geometr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Mathematics
Mathematics is an area of knowledge that includes the topics of numbers, formulas and related structures, shapes and the spaces in which they are contained, and quantities and their changes. These topics are represented in modern mathematics with the major subdisciplines of number theory, algebra, geometry, and analysis, respectively. There is no general consensus among mathematicians about a common definition for their academic discipline. Most mathematical activity involves the discovery of properties of abstract objects and the use of pure reason to prove them. These objects consist of either abstractions from nature orin modern mathematicsentities that are stipulated to have certain properties, called axioms. A ''proof'' consists of a succession of applications of deductive rules to already established results. These results include previously proved theorems, axioms, andin case of abstraction from naturesome basic properties that are considered true starting poin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Herbert Federer
Herbert Federer (July 23, 1920 – April 21, 2010) was an American mathematician. He is one of the creators of geometric measure theory, at the meeting point of differential geometry and mathematical analysis.Parks, H. (2012''Remembering Herbert Federer (1920–2010)'' NAMS 59(5), 622-631. Career Federer was born July 23, 1920, in Vienna, Austria. After emigrating to the US in 1938, he studied mathematics and physics at the University of California, Berkeley, earning the Ph.D. as a student of Anthony Morse in 1944. He then spent virtually his entire career as a member of the Brown University Mathematics Department, where he eventually retired with the title of Professor Emeritus. Federer wrote more than thirty research papers in addition to his book ''Geometric measure theory''. The Mathematics Genealogy Project assigns him nine Ph.D. students and well over a hundred subsequent descendants. His most productive students include the late Frederick J. Almgren, Jr. (1933–1997), ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Manifold
In mathematics, a manifold is a topological space that locally resembles Euclidean space near each point. More precisely, an n-dimensional manifold, or ''n-manifold'' for short, is a topological space with the property that each point has a neighborhood that is homeomorphic to an open subset of n-dimensional Euclidean space. One-dimensional manifolds include lines and circles, but not lemniscates. Two-dimensional manifolds are also called surfaces. Examples include the plane, the sphere, and the torus, and also the Klein bottle and real projective plane. The concept of a manifold is central to many parts of geometry and modern mathematical physics because it allows complicated structures to be described in terms of well-understood topological properties of simpler spaces. Manifolds naturally arise as solution sets of systems of equations and as graphs of functions. The concept has applications in computer-graphics given the need to associate pictures with coordinates ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Orientability
In mathematics, orientability is a property of some topological spaces such as real vector spaces, Euclidean spaces, surfaces, and more generally manifolds that allows a consistent definition of "clockwise" and "counterclockwise". A space is orientable if such a consistent definition exists. In this case, there are two possible definitions, and a choice between them is an orientation of the space. Real vector spaces, Euclidean spaces, and spheres are orientable. A space is non-orientable if "clockwise" is changed into "counterclockwise" after running through some loops in it, and coming back to the starting point. This means that a geometric shape, such as , that moves continuously along such a loop is changed into its own mirror image . A Möbius strip is an example of a non-orientable space. Various equivalent formulations of orientability can be given, depending on the desired application and level of generality. Formulations applicable to general topological manifolds ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Flat Convergence
In mathematics, flat convergence is a notion for convergence of submanifolds of Euclidean space. It was first introduced by Hassler Whitney in 1957, and then extended to integral currents by Federer and Fleming in 1960. It forms a fundamental part of the field of geometric measure theory. The notion was applied to find solutions to Plateau's problem. In 2001 the notion of an integral current was extended to arbitrary metric spaces by Ambrosio and Kirchheim. Integral currents A ''k''-dimensional current ''T'' is a linear functional on the space \Omega^k_c(\mathbb^n) of smooth, compactly supported ''k''-forms. For example, given a Lipschitz map from a manifold into Euclidean space, F: N^k \to \mathbb^n, one has an integral current ''T''(''ω'') defined by integrating the pullback of the differential ''k''-form, ''ω'', over ''N''. Currents have a notion of boundary \partial (which is the usual boundary when ''N'' is a manifold with boundary) and a notion of ma ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Metric Space
In mathematics, a metric space is a set together with a notion of '' distance'' between its elements, usually called points. The distance is measured by a function called a metric or distance function. Metric spaces are the most general setting for studying many of the concepts of mathematical analysis and geometry. The most familiar example of a metric space is 3-dimensional Euclidean space with its usual notion of distance. Other well-known examples are a sphere equipped with the angular distance and the hyperbolic plane. A metric may correspond to a metaphorical, rather than physical, notion of distance: for example, the set of 100-character Unicode strings can be equipped with the Hamming distance, which measures the number of characters that need to be changed to get from one string to another. Since they are very general, metric spaces are a tool used in many different branches of mathematics. Many types of mathematical objects have a natural notion of distance a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Tangent Space
In mathematics, the tangent space of a manifold generalizes to higher dimensions the notion of '' tangent planes'' to surfaces in three dimensions and ''tangent lines'' to curves in two dimensions. In the context of physics the tangent space to a manifold at a point can be viewed as the space of possible velocities for a particle moving on the manifold. Informal description In differential geometry, one can attach to every point x of a differentiable manifold a ''tangent space''—a real vector space that intuitively contains the possible directions in which one can tangentially pass through x . The elements of the tangent space at x are called the '' tangent vectors'' at x . This is a generalization of the notion of a vector, based at a given initial point, in a Euclidean space. The dimension of the tangent space at every point of a connected manifold is the same as that of the manifold itself. For example, if the given manifold is a 2 - sphere, then one can pi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Radon Measure
In mathematics (specifically in measure theory), a Radon measure, named after Johann Radon, is a measure on the σ-algebra of Borel sets of a Hausdorff topological space ''X'' that is finite on all compact sets, outer regular on all Borel sets, and inner regular on open sets. These conditions guarantee that the measure is "compatible" with the topology of the space, and most measures used in mathematical analysis and in number theory are indeed Radon measures. Motivation A common problem is to find a good notion of a measure on a topological space that is compatible with the topology in some sense. One way to do this is to define a measure on the Borel sets of the topological space. In general there are several problems with this: for example, such a measure may not have a well defined support. Another approach to measure theory is to restrict to locally compact Hausdorff spaces, and only consider the measures that correspond to positive linear functionals on t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Rectifiable Set
In mathematics, a rectifiable set is a set that is smooth in a certain measure-theoretic sense. It is an extension of the idea of a rectifiable curve to higher dimensions; loosely speaking, a rectifiable set is a rigorous formulation of a piece-wise smooth set. As such, it has many of the desirable properties of smooth manifolds, including tangent spaces that are defined almost everywhere. Rectifiable sets are the underlying object of study in geometric measure theory. Definition A Borel subset E of Euclidean space \mathbb^n is said to be m-rectifiable set if E is of Hausdorff dimension m, and there exist a countable collection \ of continuously differentiable maps :f_i:\mathbb^m \to \mathbb^n such that the m-Hausdorff measure \mathcal^m of :E\setminus \bigcup_^\infty f_i\left(\mathbb^m\right) is zero. The backslash here denotes the set difference. Equivalently, the f_i may be taken to be Lipschitz continuous without altering the definition. Other authors have different defin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Plateau's Laws
Plateau's laws describe the structure of soap films. These laws were formulated in the 19th century by the Belgian physicist Joseph Plateau from his experimental observations. Many patterns in nature are based on foams obeying these laws. Laws for soap films Plateau's laws describe the shape and configuration of soap films as follows: # Soap films are made of entire (unbroken) smooth surfaces. # The mean curvature of a portion of a soap film is everywhere constant on any point on the same piece of soap film. # Soap films always meet in threes along an edge called a Plateau border, and they do so at an angle of arccos(−) = 120°. # These Plateau borders meet in fours at a vertex, at the tetrahedral angle of arccos(−) ≈ 109.47°. Configurations other than those of Plateau's laws are unstable, and the film will quickly tend to rearrange itself to conform to these laws. That these laws hold for minimal surfaces was proved mathematically by Jean Taylor using geom ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Frederick J
Frederick may refer to: People * Frederick (given name), the name Nobility Anhalt-Harzgerode * Frederick, Prince of Anhalt-Harzgerode (1613–1670) Austria * Frederick I, Duke of Austria (Babenberg), Duke of Austria from 1195 to 1198 * Frederick II, Duke of Austria (1219–1246), last Duke of Austria from the Babenberg dynasty * Frederick the Fair (Frederick I of Austria (Habsburg), 1286–1330), Duke of Austria and King of the Romans Baden * Frederick I, Grand Duke of Baden (1826–1907), Grand Duke of Baden * Frederick II, Grand Duke of Baden (1857–1928), Grand Duke of Baden Bohemia * Frederick, Duke of Bohemia (died 1189), Duke of Olomouc and Bohemia Britain * Frederick, Prince of Wales (1707–1751), eldest son of King George II of Great Britain Brandenburg/Prussia * Frederick I, Elector of Brandenburg (1371–1440), also known as Frederick VI, Burgrave of Nuremberg * Frederick II, Elector of Brandenburg (1413–1470), Margrave of Brandenburg * Frederick Will ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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Jean Taylor
Jean Ellen Taylor (born 1944) is an American mathematician who is a professor emerita at Rutgers University and visiting faculty at Courant Institute of Mathematical Sciences of New York University. Biography Taylor was born in Northern California. She did her undergraduate studies at Mount Holyoke College, graduating summa cum laude with an A.B. in 1966. She began her graduate studies in chemistry at the University of California, Berkeley, but after receiving an M.Sc. she switched to mathematics under the mentorship of S. S. Chern and then transferred to the University of Warwick and received a second M.Sc. in mathematics there. She completed a doctorate in 1973 from Princeton University under the supervision of Frederick J. Almgren, Jr. Taylor joined the Rutgers faculty in 1973, and retired in 2002. She was president of the Association for Women in Mathematics from 1999 to 2001. She has been married three times, to mathematicians John Guckenheimer and Fred Almgren, and to fi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |