Results 61 to 70 of about 20,911 (165)
Chromatic and clique numbers of a class of perfect graphs [PDF]
Transactions on Combinatorics, 2015 Let p be a prime number and n be a positive integer. The graph G p (n) is a graph with vertex set [n]=1,2,ldots,n , in which there is an arc from u to v if and only if uneqv and pnmidu+v . In this paper it is shown that G p (n) is a perfect
Mohammad Reza Fander
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Journal of Combinatorial Theory, Series B, 2016 zbMATH Open Web Interface contents unavailable due to conflicting licenses.
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Chromatic number via Turán number
Discrete Mathematics, 2017 A Kneser representation KG(H) for a graph G is a bijective assignment of hyperedges of a hypergraph H to the vertices of G such that two vertices of G are adjacent if and only if the corresponding hyperedges are disjoint. In this paper, we introduce a colored version of the Turan number and use that to determine the chromatic number of some families of
Meysam Alishahi, Hossein Hajiabolhassan
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Global Dominator Chromatic Number of Certain Graphs [PDF]
Mathematics Interdisciplinary ResearchFor a graph G=(V,E) and a vertex subset $D\subseteq V$, a vertex $v\in V$ is called a dominator of D if v is adjacent to every vertex in D, and an anti-dominator of D if v is not adjacent to any vertex in D. Given a coloring $C=\{V_{1},V_{2},\ldots,
Hadi Nouri Samani +2 more
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Journal of Symbolic Logic, 2008 AbstractWe show that if add(null) = c, then the globally Baire and universally measurable chromatic numbers of the graph of any Borel function on a Polish space are equal and at most three. In particular, this holds for the graph of the unilateral shift on [ℕ]ℕ, although its Borel chromatic number is ℵ0.
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The chromatic number of heptagraphs
Journal of Graph TheoryAbstractA pentagraph is a graph without cycles of length 3 or 4 and without induced cycles of odd length at least 7, and a heptagraph is one without cycles of length less than 7 and without induced cycles of odd length at least 9. Chudnovsky and Seymour proved that every pentagraph is 3‐colorable.
Di Wu, Baogang Xu, Yian Xu
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The Incidence Chromatic Number of Toroidal Grids
Discussiones Mathematicae Graph Theory, 2013 An incidence in a graph G is a pair (v, e) with v ∈ V (G) and e ∈ E(G), such that v and e are incident. Two incidences (v, e) and (w, f) are adjacent if v = w, or e = f, or the edge vw equals e or f.
Sopena Éric, Wu Jiaojiao
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The locating-chromatic number for Halin graphs
Communications in Combinatorics and Optimization, 2017 Let $G$ be a connected graph. Let $f$ be a proper $k$-coloring of $G$ and $\Pi=\{R_1,R_2,\ldots, R_k\}$ be an ordered partition of $V(G)$ into color classes. For any vertex $v$ of $G,$ define the {\em color code} $c_\Pi(v)$ of $v$ with respect to $\
I.A. Purwasih +4 more
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Chromatic Number of Pseudo-Von neuman Regular Graph
Ibn Al-Haitham Journal for Pure and Applied Sciences, 2020 Let R be a commutative ring , the pseudo – von neuman regular graph of the ring R is define as a graph whose vertex set consists of all elements of R and any two distinct vertices a and b are adjacent if and only if , this graph denoted by
Nabeel E. Arif, Nermen J. Khalel
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Some Equal Degree Graph Edge Chromatic Number
MATEC Web of Conferences, 2016 Let G(V, E) be a simple graph and k is a positive integer, if it exists a mapping of f, and satisfied with f(e1)≠6 = f(e2) for two incident edges e1,e2∉E(G), f(e1)≠6=f(e2), then f is called the k-proper-edge coloring of G(k-PEC for short).
Liu Jun +4 more
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