搜索结果: 121-135 共查到“知识库 组合数学”相关记录451条 . 查询时间(5.212 秒)
Bounds for graph regularity and removal lemmas
graph regularity removal lemmas Combinatorics
2011/9/20
Abstract: We show, for any positive integer k, that there exists a graph in which any equitable partition of its vertices into k parts has at least ck^2/\log^* k pairs of parts which are not \epsilon-...
Abstract: We characterize permutations whose Bruhat graphs can be drawn in the plane. In particular, we show this property, as well as that of having having length at most a fixed l, is characterized ...
Distance sets of universal and Urysohn metric spaces
Distance sets of universal Urysohn metric spaces Combinatorics
2011/9/20
Abstract: A metric space $\mathrm{M}=(M;\de)$ is {\em homogeneous} if for every isometry $f$ of a finite subspace of $\mathrm{M}$ to a subspace of $\mathrm{M}$ there exists an isometry of $\mathrm{M}$...
On a conjecture of Erdos and Simonovits: Even Cycles
conjecture of Erdos and Simonovits Even Cycles Combinatorics
2011/9/19
Abstract: Let $\mc{F}$ be a family of graphs. A graph is {\em $\mc{F}$-free} if it contains no copy of a graph in $\mc{F}$ as a subgraph. A cornerstone of extremal graph theory is the study of the {\e...
On abelian and additive complexity in infinite words
additive complexity infinite words Combinatorics
2011/9/19
Abstract: The study of the structure of infinite words having bounded abelian complexity was initiated by G. Richomme, K. Saari, and L. Q. Zamboni. In this note we define bounded additive complexity f...
Local-to-global principles for rotor walk
cycle popping hitting sequence monoid action rotorrouter model sandpile group sandpile monoid
2011/9/19
Abstract: In rotor walk on a finite directed graph, the exits from each vertex follow a prescribed periodic sequence. Here we consider the case of rotor walk where a particle starts from a designated ...
Inscribing a regular octahedron into polytopes
inscribed polytopes spheric geometry Combinatorics
2011/9/19
Abstract: We prove that any simple polytope (and some non-simple polytopes) in $\mathbb R^3$ admits an inscribed regular octahedron.
On epimorphisms of spherical Moufang buildings
spherical Moufang buildings epimorphisms Combinatorics
2011/9/16
Abstract: In this paper we classify the the epimorphisms of irreducible spherical Moufang buildings (of rank at least 2) defined over a field. As an application we characterize indecomposable epimorph...
Actions and identities on set partitions
Actions and identities set partitions Combinatorics
2011/9/16
Abstract: A labeled set partition is a partition of a set of integers whose arcs are labeled by nonzero elements of an abelian group $A$. Inspired by the action of the linear characters of the unitria...
Crystal energy functions via the charge in types A and C
Crystal energy functions Combinatorics
2011/9/16
Abstract: The Ram-Yip formula for Macdonald polynomials (at t=0) provides a statistic which we call charge. In types A and C it can be defined on tensor products of Kashiwara-Nakashima single column c...
The Discrete Analog of the Malgrange-Ehrenpreis Theorem
the Malgrange-Ehrenpreis Theorem The Discrete Analog Combinatorics
2011/9/19
Abstract: One of the landmarks of the modern theory of partial differential equations is the Malgrange- Ehrenpreis theorem that states that every non-zero linear partial differential operator with con...
Maximal supports and Schur-positivity among connected skew shapes
Symmetric function Schur-positive support skew shape ribbon
2011/9/19
Abstract: The Schur-positivity order on skew shapes is defined by B \leq A if the difference s_A - s_B is Schur-positive. It is an open problem to determine those connected skew shapes that are maxima...
Abstract: Generalized $t$-designs, which form a common generalization of objects such as $t$-designs, resolvable designs and orthogonal arrays, were defined by Cameron [P.J. Cameron, A generalisation ...
Symmetric chain decomposition for cyclic quotients of Boolean algebras and relation to cyclic crystals
Symmetric chain decomposition Boolean algebras cyclic crystals
2011/9/15
Abstract: The quotient of a Boolean algebra by a cyclic group is proven to have a symmetric chain decomposition. This generalizes earlier work of Griggs, Killian and Savage on the case of prime order,...
Abstract: We prove that, for each nonnegative integer k and each matroid N, if M is a 3-connected matroid containing N as a minor, and the the branch width of M is sufficiently large, then there is a ...