منابع مشابه
Flag algebras
Asymptotic extremal combinatorics deals with questions that in the language of model theory can be re-stated as follows. For finite models M, N of an universal theory without constants and function symbols (like graphs, digraphs or hypergraphs), let p(M, N) be the probability that a randomly chosen sub-model of N with |M | elements is isomorphic to M . Which asymptotic relations exist between t...
متن کاملOn Quantum Flag Algebras
Let G be a semisimple simply connected algebraic group over an algebraically closed field of characteristic 0. Let V be a simple finite-dimensional G-module and let y be its highest weight vector. It is a classical result of B. Kostant that the algebra of functions on the closure of G · y is quadratic. In this paper we generalize this result to the case of the quantum group Uq(g). The proof use...
متن کاملImprimitive flag-transitive symmetric designs
A recent paper of O’Reilly Regueiro obtained an explicit upper bound on the number of points of a flagtransitive, point-imprimitive, symmetric design in terms of the number of blocks containing two points. We improve that upper bound and give a complete list of feasible parameter sequences for such designs for which two points lie in at most ten blocks. Classifications are available for some of...
متن کاملFlag Algebras: An Interim Report
For the most part, this article is a survey of concrete results in extremal combinatorics obtained with the method of flag algebras. But our survey is also preceded, interleaved and concluded with a few general digressions about the method itself. Also, instead of giving a plain and unannotated list of results, we try to divide our account into several connected stories that often include histo...
متن کاملSymmetric Graphs and Flag Graphs
With any G-symmetric graph admitting a nontrivial G-invariant partition B, we may associate a natural ‘‘cross-sectional’’ geometry, namely the 1-design DðBÞ 1⁄4 ðB; BðBÞ; IÞ in which IC for 2B and C 2 BðBÞ if and only if is adjacent to at least one vertex in C, where B2B and BðBÞ is the neighbourhood of B in the quotient graph B of with respect to B. In a vast number of cases, the dual 1-design...
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ژورنال
عنوان ژورنال: Journal of Combinatorial Theory, Series A
سال: 1988
ISSN: 0097-3165
DOI: 10.1016/0097-3165(88)90007-6