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Supersolvable Lattice
In mathematics, a supersolvable lattice is a graded poset, graded Lattice (order), lattice that has a maximal total order#Chains, chain of elements, each of which obeys a certain modularity relationship. The definition encapsulates many of the nice properties of lattice of subgroups, lattices of subgroups of supersolvable groups. Motivation A finite group (mathematics), group G is said to be ''supersolvable'' if it admits a maximal subgroup series, chain (or ''series'') of subgroups so that each subgroup in the chain is normal in G. A normal subgroup has been known since the 1940s to be left and (dual) right Modular pair, modular as an element of the lattice of subgroups. Richard P. Stanley, Richard Stanley noticed in the 1970s that certain geometric lattices, such as the partition lattice, obeyed similar properties, and gave a lattice-theoretic abstraction. Definition A finite graded lattice L is supersolvable if it admits a maximal chain \mathbf of elements (called an M-chain o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Graded Poset
In mathematics, in the branch of combinatorics, a graded poset is a partially-ordered set (poset) ''P'' equipped with a rank function ''ρ'' from ''P'' to the set N of all natural number In mathematics, the natural numbers are the numbers 0, 1, 2, 3, and so on, possibly excluding 0. Some start counting with 0, defining the natural numbers as the non-negative integers , while others start with 1, defining them as the positive in ...s. ''ρ'' must satisfy the following two properties: * The rank function is compatible with the ordering, meaning that for all ''x'' and ''y'' in the order, if ''x'' < ''y'' then ''ρ''(''x'') < ''ρ''(''y''), and * The rank is consistent with the covering relation of the ordering, meaning that for all ''x'' and ''y'', if ''y'' covers ''x'' then ''ρ''(''y'') = ''ρ''(''x'') + 1. The value of the rank functio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Noncrossing Partition
In combinatorial mathematics, the topic of noncrossing partitions has assumed some importance because of (among other things) its application to the theory of free probability. The number of noncrossing partitions of a set of ''n'' elements is the ''n''th Catalan number. The number of noncrossing partitions of an ''n''-element set with ''k'' blocks is found in the Narayana number triangle. Definition A partition of a set ''S'' is a set of non-empty, pairwise disjoint subsets of ''S'', called "parts" or "blocks", whose union is all of ''S''. Consider a finite set that is linearly ordered, or (equivalently, for purposes of this definition) arranged in a cyclic order like the vertices of a regular ''n''-gon. No generality is lost by taking this set to be ''S'' = . A noncrossing partition of ''S'' is a partition in which no two blocks "cross" each other, i.e., if ''a'' and ''b'' belong to one block and ''x'' and ''y'' to another, they are not arranged in the order ''a x b y''. If ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Shelling (topology)
In mathematics, a shelling of a simplicial complex is a way of gluing it together from its maximal simplices (simplices that are not a face of another simplex) in a well-behaved way. A complex admitting a shelling is called shellable. Definition A ''d''-dimensional simplicial complex is called pure if its maximal simplices all have dimension ''d''. Let \Delta be a finite or countably infinite simplicial complex. An ordering C_1,C_2,\ldots of the maximal simplices of \Delta is a shelling if, for all k=2,3,\ldots, the complex :B_k:=\Big(\bigcup_^C_i\Big)\cap C_k is pure and of dimension one smaller than \dim C_k. That is, the "new" simplex C_k meets the previous simplices along some union B_k of top-dimensional simplices of the boundary of C_k. If B_k is the entire boundary of C_k then C_k is called spanning. For \Delta not necessarily countable, one can define a shelling as a well-ordering of the maximal simplices of \Delta having analogous properties. Properties * A shellable c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Order Complex
In mathematics, the poset topology associated to a poset (''S'', ≤) is the Alexandrov topology (open sets are upper sets) on the poset of finite chains of (''S'', ≤), ordered by inclusion. Let ''V'' be a set of vertices. An abstract simplicial complex Δ is a set of finite sets of vertices, known as faces \sigma \subseteq V, such that ::\forall \rho \, \forall \sigma \!: \ \rho \subseteq \sigma \in \Delta \Rightarrow \rho \in \Delta. Given a simplicial complex Δ as above, we define a (point set) topology on Δ by declaring a subset \Gamma \subseteq \Delta be closed if and only if Γ is a simplicial complex, i.e. ::\forall \rho \, \forall \sigma \!: \ \rho \subseteq \sigma \in \Gamma \Rightarrow \rho \in \Gamma. This is the Alexandrov topology In general topology, an Alexandrov topology is a topology in which the intersection of an ''arbitrary'' family of open sets is open (while the definition of a topology only requires this for a ''finite'' family). Equivalently, an Ale ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Edge Lexicographic Labeling
Edge or EDGE may refer to: Technology Computing * Edge computing, a network load-balancing system * Edge device, an entry point to a computer network * Adobe Edge, a graphical development application * Microsoft Edge, a web browser developed by Microsoft * Microsoft Edge Legacy, a discontinued web browser developed by Microsoft * EdgeHTML, the layout engine used in Microsoft Edge Legacy * ThinkPad Edge, a Lenovo laptop computer series marketed from 2010 * Silhouette edge, in computer graphics, a feature of a 3D body projected onto a 2D plane * Explicit data graph execution, a computer instruction set architecture Telecommunication(s) * EDGE (telecommunication), a 2G digital cellular communications technology * Edge Wireless, an American mobile phone provider * Motorola Edge series, a series of smartphones made by Motorola * Samsung Galaxy Note Edge, a phablet made by Samsung * Samsung Galaxy S7 Edge or Samsung Galaxy S6 Edge, smartphones made by Samsung * Ubuntu Edge, a p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Supersolvable Arrangement
In mathematics, a supersolvable arrangement is a hyperplane arrangement that has a maximal flag consisting of modular elements. Equivalently, the intersection semilattice of the arrangement is a supersolvable lattice, in the sense of Richard P. Stanley. As shown by Hiroaki Terao, a complex hyperplane arrangement is supersolvable if and only if its complement is fiber-type. Examples include arrangements associated with Coxeter group In mathematics, a Coxeter group, named after H. S. M. Coxeter, is an abstract group that admits a formal description in terms of reflections (or kaleidoscopic mirrors). Indeed, the finite Coxeter groups are precisely the finite Euclidean ref ...s of type A and B. The Orlik–Solomon algebra of every supersolvable arrangement is a Koszul algebra; whether the converse is true is an open problem.{{cite journal, first=Sergey, last= Yuzvinsky, title= Orlik–Solomon algebras in algebra and topology, journal= Russian Mathematical Surveys, vo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Koszul Algebra
In abstract algebra, a Koszul algebra R is a graded k-algebra over which the ground field k has a linear minimal graded free resolution, ''i.e.'', there exists an exact sequence: :\cdots \rightarrow (R(-i))^ \rightarrow \cdots \rightarrow (R(-2))^ \rightarrow (R(-1))^ \rightarrow R \rightarrow k \rightarrow 0. for some nonnegative integers b_i. Here R(-j) is the graded algebra R with grading shifted up by j, ''i.e.'' R(-j)_i = R_, and the exponent b_i refers to the b_i-fold direct sum. Choosing bases for the free modules in the resolution, the chain maps are given by matrices, and the definition requires the matrix entries to be zero or linear forms. An example of a Koszul algebra is a polynomial ring over a field, for which the Koszul complex is the minimal graded free resolution of the ground field. There are Koszul algebras whose ground fields have infinite minimal graded free resolutions, ''e.g'', R = k ,y(xy) . The concept is named after the French mathematician Jean-Lo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Arrangement Of Hyperplanes
In geometry and combinatorics, an arrangement of hyperplanes is an arrangement of a finite set ''A'' of hyperplanes in a linear, affine, or projective space ''S''. Questions about a hyperplane arrangement ''A'' generally concern geometrical, topological, or other properties of the complement, ''M''(''A''), which is the set that remains when the hyperplanes are removed from the whole space. One may ask how these properties are related to the arrangement and its intersection semilattice. The intersection semilattice of ''A'', written ''L''(''A''), is the set of all subspaces that are obtained by intersecting some of the hyperplanes; among these subspaces are ''S'' itself, all the individual hyperplanes, all intersections of pairs of hyperplanes, etc. (excluding, in the affine case, the empty set). These intersection subspaces of ''A'' are also called the flats of ''A''. The intersection semilattice ''L''(''A'') is partially ordered by ''reverse inclusion''. If the whole space ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Matroid
In combinatorics, a matroid is a structure that abstracts and generalizes the notion of linear independence in vector spaces. There are many equivalent ways to define a matroid Axiomatic system, axiomatically, the most significant being in terms of: independent sets; bases or circuits; rank functions; closure operators; and closed sets or ''flats''. In the language of partially ordered sets, a finite simple matroid is equivalent to a geometric lattice. Matroid theory borrows extensively from the terms used in both linear algebra and graph theory, largely because it is the abstraction of various notions of central importance in these fields. Matroids have found applications in geometry, topology, combinatorial optimization, network theory, and coding theory. Definition There are many Cryptomorphism, equivalent ways to define a (finite) matroid. Independent sets In terms of independence, a finite matroid M is a pair (E, \mathcal), where E is a finite set (called the ''gro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Perfect Elimination Ordering
Perfect commonly refers to: * Perfection; completeness, and excellence * Perfect (grammar), a grammatical category in some languages Perfect may also refer to: Film and television * ''Perfect'' (1985 film), a romantic drama * ''Perfect'' (2018 film), a science fiction thriller * "Perfect" (''Doctors''), a 2004 television episode Literature * ''Perfect'' (Friend novel), a 2004 novel by Natasha Friend * ''Perfect'' (Hopkins novel), a young adult novel by Ellen Hopkins * ''Perfect'' (Joyce novel), a 2013 novel by Rachel Joyce * ''Perfect'' (Shepard novel), a Pretty Little Liars novel by Sara Shepard * ''Perfect'', a young adult science fiction novel by Dyan Sheldon Music * Perfect interval, in music theory * Perfect Records, a record label Artists * Perfect (musician) (born 1980), reggae singer * Perfect (Polish band) * Perfect (American band), an American alternative rock group Albums * ''Perfect'' (Intwine album) (2004) * ''Perfect'' (Half Japanese album) (201 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
