Results 51 to 60 of about 163 (126)
On the maximal Aa -index of graphs with a prescribed number of edges
Special MatricesFor any real number α∈[0,1]\alpha \in \left[\mathrm{0,1}], by the Aα{A}_{\alpha }-matrix of a graph GG, we mean the matrix Aα(G)=αD(G)+(1−α)A(G){A}_{\alpha }\left(G)=\alpha D\left(G)+\left(1-\alpha )A\left(G), where A(G)A\left(G) and D(G)D\left(G) are ...
Chang Ting-Chung, Tam Bit-Shun
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The Degree-Diameter Problem for Outerplanar Graphs
Discussiones Mathematicae Graph Theory, 2017 For positive integers Δ and D we define nΔ,D to be the largest number of vertices in an outerplanar graph of given maximum degree Δ and diameter D. We prove that nΔ,D=ΔD2+O (ΔD2−1)$n_{\Delta ,D} = \Delta ^{{D \over 2}} + O\left( {\Delta ^{{D \over 2 ...
Dankelmann Peter +2 more
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High Girth Hypergraphs with Unavoidable Monochromatic or Rainbow Edges
Discussiones Mathematicae Graph Theory, 2022 A classical result of Erdős and Hajnal claims that for any integers k, r, g ≥ 2 there is an r-uniform hypergraph of girth at least g with chromatic number at least k.
Axenovich Maria, Karrer Annette
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Sequences of Maximal Degree Vertices in Graphs [PDF]
, 2004 2000 Mathematics Subject Classification: 05C35.Let Γ(M ) where M ⊂ V (G) be the set of all vertices of the graph G adjacent to any vertex of M. If v1, . . . , vr is a vertex sequence in G such that Γ(v1, . . . , vr ) = ∅ and vi is a maximal degree vertex
Khadzhiivanov, Nickolay, Nenov, Nedyalko
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Hamiltonian and Pancyclic Graphs in the Class of Self-Centered Graphs with Radius Two
Discussiones Mathematicae Graph Theory, 2018 The paper deals with Hamiltonian and pancyclic graphs in the class of all self-centered graphs of radius 2. For both of the two considered classes of graphs we have done the following. For a given number n of vertices, we have found an upper bound of the
Hrnčiar Pavel, Monoszová Gabriela
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Avoiding rainbow 2-connected subgraphs
Open Mathematics, 2017 While defining the anti-Ramsey number Erdős, Simonovits and Sós mentioned that the extremal colorings may not be unique. In the paper we discuss the uniqueness of the colorings, generalize the idea of their construction and show how to use it to ...
Gorgol Izolda
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Discussiones Mathematicae Graph Theory, 2018 A total-colored graph G is rainbow total-connected if any two vertices of G are connected by a path whose edges and internal vertices have distinct colors.
Sun Yuefang, Jin Zemin, Tu Jianhua
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On the Sizes of (k, l)-Edge-Maximal r-Uniform Hypergraphs
Discussiones Mathematicae Graph Theory, 2023 Let H = (V, E) be a hypergraph, where V is a set of vertices and E is a set of non-empty subsets of V called edges. If all edges of H have the same cardinality r, then H is an r-uniform hypergraph; if E consists of all r-subsets of V, then H is a ...
Tian Yingzhi +3 more
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The intersection density of cubic arc-transitive graphs with \(2\)-arc-regular full automorphism group equal to \( \operatorname{PGL}_{2}(q)\) [PDF]
The intersection density of a transitive permutation group \(G\leq \operatorname{Sym}(V)\) is the ratio between the largest size of a subset of \(G\) in which any two agree on at least one element of \(V\), and the order of a point-stabilizer of \(G ...
Meagher, Karen +1 more
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Some News about the Independence Number of a Graph [PDF]
, 2000 For a finite undirected graph G on n vertices some continuous optimization problems taken over the n-dimensional cube are presented and it is proved that their optimum values equal the independence number of G. Keywords: graph, independence.
Harant, Jochen, Jochen Harant
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