Browsing Combinatorics and Optimization by Subject "hypergraphs"
Now showing items 1-5 of 5
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List colouring hypergraphs and extremal results for acyclic graphs
(University of Waterloo, 2008-05-21)We study several extremal problems in graphs and hypergraphs. The first one is on list-colouring hypergraphs, which is a generalization of the ordinary colouring of hypergraphs. We discuss two methods for determining the ... -
On the orientation of hypergraphs
(University of Waterloo, 2011-01-13)This is an expository thesis. In this thesis we study out-orientations of hypergraphs, where every hyperarc has one tail vertex. We study hypergraphs that admit out-orientations covering supermodular-type connectivity ... -
Ramsey-nice families of graphs
(Elsevier, 2018-08)For a finite family $\cF$ of fixed graphs let $R_k(\cF)$ be the smallest integer $n$ for which every $k$-coloring of the edges of the complete graph $K_n$ yields a monochromatic copy of some $F\in\cF$. We say that $\cF$ ... -
A Stability Theorem for Matchings in Tripartite 3-Graphs
(Cambridge University Press, 2018-04-02)It follows from known results that every regular tripartite hypergraph of positive degree, with n vertices in each class, has matching number at least n/2. This bound is best possible, and the extremal configuration is ... -
Symmetries
(University of Waterloo, 2016-10-03)Automorphisms of graphs, hypergraphs and disgraphs are investigated. The invariance of the chromatic polynomial in the rotor effect is disproved. New invariance results are obtained. It is shown that given any integer k ...