منابع مشابه
Hypergraphs, Quasi-randomness, and Conditions for Regularity
Haviland and Thomason and Chung and Graham were the first to investigate systematically some properties of quasi-random hypergraphs. In particular, in a series of articles, Chung and Graham considered several quite disparate properties of random-like hypergraphs of density 1/2 and proved that they are in fact equivalent. The central concept in their work turned out to be the so called deviation...
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Let H=(V,E) be a hypergraph. A panchromatic t-colouring of H is a t-colouring of its vertices such that each edge has at least one vertex of each colour; and H is panchromatically t-choosable if, whenever each vertex is given a list of t colours, the vertices can be coloured from their lists in such a way that each edge receives at least t different colours. The Hall ratio of H is h(H) =min {∣∣...
متن کاملNecessary Spectral Conditions for Coloring Hypergraphs
Hoffman proved that for a simple graph G, the chromatic number χ(G) obeys χ(G) ≥ 1 − λ1 λn where λ1 and λn are the maximal and minimal eigenvalues of the adjacency matrix of G respectively. Lovász later showed that χ(G) ≥ 1− λ1 λn for any (perhaps negatively) weighted adjacency matrix. In this paper, we give a probabilistic proof of Lovász’s theorem, then extend the technique to derive generali...
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In an in nite digraph D an edge e is reachable from an edge e if there exists an alternating walk in D whose initial and terminal edges are e and e Reachability is an equivalence relation and if D is arc transitive then this relation is either universal or all of its equiv alence classes induce isomorphic bipartite digraphs In Question Cameron Praeger and Wormald asked if there exist highly arc...
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ژورنال
عنوان ژورنال: Algebraic structures and their applications
سال: 2018
ISSN: 2382-9761,2423-3447
DOI: 10.29252/asta.5.2.45