Results 31 to 40 of about 8,142 (223)

Diagonal Forms, Linear Algebraic Methods and Ramsey-Type Problems [PDF]

open access: yes, 2013
This thesis focuses mainly on linear algebraic aspects of combinatorics. Let N_t(H) be an incidence matrix with edges versus all subhypergraphs of a complete hypergraph that are isomorphic to H. Richard M.
Wong, Wing Hong Tony
core   +1 more source

An abstract approach to polychromatic coloring: Shallow hitting sets in ABA-free hypergraphs and pseudohalfplanes

open access: yesJournal of Computational Geometry, 2019
The goal of this paper is to give a new, abstract approach to cover-decomposition and polychromatic colorings using hypergraphs on ordered vertex sets.
Balázs Keszegh, Dömötör Pálvölgyi
doaj   +1 more source

Traces of hypergraphs

open access: yesJournal of the London Mathematical Society, 2019
Let $\text{Tr}(n,m,k)$ denote the largest number of distinct projections onto $k$ coordinates guaranteed in any family of $m$ binary vectors of length $n$. The classical Sauer-Perles-Shelah Lemma implies that $\text{Tr}(n, n^r, k) = 2^k$ for $k \le r$. While determining $\text{Tr}(n,n^r,k)$ precisely for general $k$ seems hopeless even for constant $r$,
Noga Alon, Guy Moshkovitz, Noam Solomon
openaire   +3 more sources

On partitioning of hypergraphs

open access: yesDiscrete Mathematics, 2007
The edge-isoperimetric problem on graphs (EIP), namely for a given integer \(m\) and graph \(G=(V,E)\) to find a subset \(A\) of the vertices of \(G\) of cardinality \(m\) so that the number of edges of \(G\) connecting vertices in \(A\) to vertices in \(V\setminus A\), is minimized (version 1), or such that the number of edges of \(G\) induced by \(A\)
S. Bezrukov, Battiti, Roberto
openaire   +3 more sources

On Matchings in Hypergraphs [PDF]

open access: yesThe Electronic Journal of Combinatorics, 2012
We show that if the largest matching in a $k$-uniform hypergraph $G$ on $n$ vertices has precisely $s$ edges, and $n>2k^2s/\log k$, then $H$ has at most $\binom n k - \binom {n-s} k $ edges and this upper bound is achieved only for hypergraphs in which the set of edges consists of all $k$-subsets which intersect a given set of $s$ vertices.
Peter Frankl   +2 more
openaire   +2 more sources

07281 Open Problems – Structure Theory and FPT Algorithmcs for Graphs, Digraphs and Hypergraphs [PDF]

open access: yes, 2007
The following is a list of the problems presented on Monday, July 9, 2007 at the open-problem session of the Seminar on Structure Theory and FPT Algorithmics for Graphs, Digraphs and Hypergraphs, held at Schloss Dagstuhl in Wadern ...
Stege, Ulrike   +3 more
core   +1 more source

Maximizing Spectral Radii of Uniform Hypergraphs with Few Edges

open access: yesDiscussiones Mathematicae Graph Theory, 2016
In this paper we investigate the hypergraphs whose spectral radii attain the maximum among all uniform hypergraphs with given number of edges. In particular we characterize the hypergraph(s) with maximum spectral radius over all unicyclic hypergraphs ...
Fan Yi-Zheng   +3 more
doaj   +1 more source

Hypergraphs in m-Polar Fuzzy Environment

open access: yesMathematics, 2018
Fuzzy graph theory is a conceptual framework to study and analyze the units that are intensely or frequently connected in a network. It is used to study the mathematical structures of pairwise relations among objects. An m-polar fuzzy (mF, for short) set
Muhammad Akram, Gulfam Shahzadi
doaj   +1 more source

Cartesian product of hypergraphs: properties and algorithms [PDF]

open access: yesElectronic Proceedings in Theoretical Computer Science, 2009
Cartesian products of graphs have been studied extensively since the 1960s. They make it possible to decrease the algorithmic complexity of problems by using the factorization of the product.
Alain Bretto   +2 more
doaj   +1 more source

Elementary definability of the class of universal hypergraphic automata in the class of semigroups [PDF]

open access: yesИзвестия Саратовского университета. Новая серия: Математика. Механика. Информатика, 2022
Hypergraphic automata are automata, state sets and output symbol sets of which are hypergraphs, being invariant under actions of transition and output functions. Universally attracting objects in the category of hypergraphic automata are called universal
Molchanov, Vladimir Aleksandrovich   +1 more
doaj   +1 more source

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