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Bruhat–Tits Building In mathematics, a building (also Tits building, Bruhat–Tits building, named after François Bruhat and Jacques Tits) is a combinatorial and geometric structure which simultaneously generalizes certain aspects of flag manifolds, finite projective planes, and Riemannian symmetric spaces [...More...]  "Bruhat–Tits Building" on: Wikipedia Yahoo Parouse 

Mathematics Mathematics Mathematics (from Greek μάθημα máthēma, "knowledge, study, learning") is the study of such topics as quantity,[1] structure,[2] space,[1] and change.[3][4][5] It has no generally accepted definition.[6][7] Mathematicians seek out patterns[8][9] and use them to formulate new conjectures. Mathematicians resolve the truth or falsity of conjectures by mathematical proof. When mathematical structures are good models of real phenomena, then mathematical reasoning can provide insight or predictions about nature. Through the use of abstraction and logic, mathematics developed from counting, calculation, measurement, and the systematic study of the shapes and motions of physical objects. Practical mathematics has been a human activity from as far back as written records exist [...More...]  "Mathematics" on: Wikipedia Yahoo Parouse 

Flag (linear Algebra) In mathematics, particularly in linear algebra, a flag is an increasing sequence of subspaces of a finitedimensional vector space V. Here "increasing" means each is a proper subspace of the next (see filtration): 0 = V 0 ⊂ V 1 ⊂ V 2 ⊂ ⋯ ⊂ V k = V . displaystyle 0 =V_ 0 subset V_ 1 subset V_ 2 subset cdots subset V_ k =V. If we write the dim Vi = di then we have 0 = d 0 < d 1 < d 2 < ⋯ < d k = n , displaystyle 0=d_ 0 <d_ 1 <d_ 2 <cdots <d_ k =n, where n is the dimension of V (assumed to be finitedimensional). Hence, we must have k ≤ n [...More...]  "Flag (linear Algebra)" on: Wikipedia Yahoo Parouse 

Hilbert Space The mathematical concept of a Hilbert space, named after David Hilbert, generalizes the notion of Euclidean space. It extends the methods of vector algebra and calculus from the twodimensional Euclidean plane and threedimensional space to spaces with any finite or infinite number of dimensions. A Hilbert space Hilbert space is an abstract vector space possessing the structure of an inner product that allows length and angle to be measured. Furthermore, Hilbert spaces are complete: there are enough limits in the space to allow the techniques of calculus to be used. Hilbert spaces arise naturally and frequently in mathematics and physics, typically as infinitedimensional function spaces. The earliest Hilbert spaces were studied from this point of view in the first decade of the 20th century by David Hilbert, Erhard Schmidt, and Frigyes Riesz [...More...]  "Hilbert Space" on: Wikipedia Yahoo Parouse 

CAT(k) Space In mathematics, a CAT ( k ) displaystyle mathbf operatorname textbf CAT (k) space, where k displaystyle k is a real number, is a specific type of metric space. Intuitively, triangles in a CAT ( k ) displaystyle operatorname CAT (k) space are "slimmer" than corresponding "model triangles" in a standard space of constant curvature k displaystyle k . In a CAT ( k ) displaystyle operatorname CAT (k) space, the curvature is bounded from above by k displaystyle k [...More...]  "CAT(k) Space" on: Wikipedia Yahoo Parouse 

Aleksandr Danilovich Aleksandrov Aleksandr Danilovich Aleksandrov (Russian: Алекса́ндр Дани́лович Алекса́ндров, alternative transliterations: Alexandr or Alexander (first name), and Alexandrov (last name)) (August 4, 1912 – July 27, 1999), was a Soviet/Russian mathematician, physicist, philosopher and mountaineer.Contents1 Scientific career 2 Awards 3 Works by Aleksandrov 4 Students of Aleksandrov 5 Mountaineering 6 See also 7 References 8 External linksScientific career[edit] Aleksandr Aleksandrov was born in 1912 in Volyn village, Ryazan Oblast.[1] He graduated from the Department of Physics Physics of Leningrad State University. His advisors there were Vladimir Fock, a physicist, and Boris Delaunay, a mathematician. In 1933 Aleksandrov worked at the State Optical Institute (GOI) and at the same time gave lectures at the Department of Mathematics Mathematics and Mechanics of the University [...More...]  "Aleksandr Danilovich Aleksandrov" on: Wikipedia Yahoo Parouse 

BN Pair In mathematics, a (B, N) pair is a structure on groups of Lie type that allows one to give uniform proofs of many results, instead of giving a large number of casebycase proofs. Roughly speaking, it shows that all such groups are similar to the general linear group over a field [...More...]  "BN Pair" on: Wikipedia Yahoo Parouse 

Tits System In mathematics, a (B, N) pair is a structure on groups of Lie type that allows one to give uniform proofs of many results, instead of giving a large number of casebycase proofs. Roughly speaking, it shows that all such groups are similar to the general linear group over a field [...More...]  "Tits System" on: Wikipedia Yahoo Parouse 

Borel Subgroup In the theory of algebraic groups, a Borel subgroup Borel subgroup of an algebraic group G is a maximal Zariski closed and connected solvable algebraic subgroup. For example, in the group GLn (n x n invertible matrices), the subgroup of invertible upper triangular matrices is a Borel subgroup. For groups realized over algebraically closed fields, there is a single conjugacy class of Borel subgroups. Borel subgroups are one of the two key ingredients in understanding the structure of simple (more generally, reductive) algebraic groups, in Jacques Tits' theory of groups with a (B,N) pair [...More...]  "Borel Subgroup" on: Wikipedia Yahoo Parouse 

Parabolic Subgroup In the theory of algebraic groups, a Borel subgroup Borel subgroup of an algebraic group G is a maximal Zariski closed and connected solvable algebraic subgroup. For example, in the group GLn (n x n invertible matrices), the subgroup of invertible upper triangular matrices is a Borel subgroup. For groups realized over algebraically closed fields, there is a single conjugacy class of Borel subgroups. Borel subgroups are one of the two key ingredients in understanding the structure of simple (more generally, reductive) algebraic groups, in Jacques Tits' theory of groups with a (B,N) pair [...More...]  "Parabolic Subgroup" on: Wikipedia Yahoo Parouse 

Algebra Algebra Algebra (from Arabic Arabic "aljabr" literally meaning "reunion of broken parts"[1]) is one of the broad parts of mathematics, together with number theory, geometry and analysis. In its most general form, algebra is the study of mathematical symbols and the rules for manipulating these symbols;[2] it is a unifying thread of almost all of mathematics.[3] As such, it includes everything from elementary equation solving to the study of abstractions such as groups, rings, and fields. The more basic parts of algebra are called elementary algebra; the more abstract parts are called abstract algebra or modern algebra. Elementary algebra Elementary algebra is generally considered to be essential for any study of mathematics, science, or engineering, as well as such applications as medicine and economics [...More...]  "Algebra" on: Wikipedia Yahoo Parouse 

Geometry Geometry Geometry (from the Ancient Greek: γεωμετρία; geo "earth", metron "measurement") is a branch of mathematics concerned with questions of shape, size, relative position of figures, and the properties of space. A mathematician who works in the field of geometry is called a geometer. Geometry Geometry arose independently in a number of early cultures as a practical way for dealing with lengths, areas, and volumes [...More...]  "Geometry" on: Wikipedia Yahoo Parouse 

Tessellation A tessellation of a flat surface is the tiling of a plane using one or more geometric shapes, called tiles, with no overlaps and no gaps. In mathematics, tessellations can be generalized to higher dimensions and a variety of geometries. A periodic tiling has a repeating pattern. Some special kinds include regular tilings with regular polygonal tiles all of the same shape, and Semiregular tilings with regular tiles of more than one shape and with every corner identically arranged. The patterns formed by periodic tilings can be categorized into 17 wallpaper groups. A tiling that lacks a repeating pattern is called "nonperiodic". An aperiodic tiling uses a small set of tile shapes that cannot form a repeating pattern. In the geometry of higher dimensions, a spacefilling or honeycomb is also called a tessellation of space. A real physical tessellation is a tiling made of materials such as cemented ceramic squares or hexagons [...More...]  "Tessellation" on: Wikipedia Yahoo Parouse 

Schreier Refinement Theorem In mathematics, the Schreier refinement theorem of group theory states that any two subnormal series of subgroups of a given group have equivalent refinements, where two series are equivalent if there is a bijection between their factor groups that sends each factor group to an isomorphic one. The theorem is named after the Austrian mathematician Otto Schreier who proved it in 1928. It provides an elegant proof of the Jordan–Hölder theorem. It is often proved using the Zassenhaus lemma. Example[edit] Consider Z / ( 2 ) × S 3 displaystyle mathbb Z /(2)times S_ 3 , where S 3 displaystyle S_ 3 is the symmetric group of degree 3 [...More...]  "Schreier Refinement Theorem" on: Wikipedia Yahoo Parouse 

Intrinsic Metric In the mathematical study of metric spaces, one can consider the arclength of paths in the space. If two points are at a given distance from each other, it is natural to expect that one should be able to get from the first point to the second along a path whose arclength is equal to (or very close to) that distance. The distance between two points of a metric space relative to the intrinsic metric is defined as the infimum of the lengths of all paths from the first point to the second [...More...]  "Intrinsic Metric" on: Wikipedia Yahoo Parouse 

JordanHölder Decomposition In abstract algebra, a composition series provides a way to break up an algebraic structure, such as a group or a module, into simple pieces. The need for considering composition series in the context of modules arises from the fact that many naturally occurring modules are not semisimple, hence cannot be decomposed into a direct sum of simple modules. A composition series of a module M is a finite increasing filtration of M by submodules such that the successive quotients are simple and serves as a replacement of the direct sum decomposition of M into its simple constituents. A composition series may not exist, and when it does, it need not be unique. Nevertheless, a group of results known under the general name Jordan–Hölder theorem asserts that whenever composition series exist, the isomorphism classes of simple pieces (although, perhaps, not their location in the composition series in question) and their multiplicities are uniquely determined [...More...]  "JordanHölder Decomposition" on: Wikipedia Yahoo Parouse 