Results 21 to 30 of about 1,119 (103)
A note on the k‐domination number of a graph
International Journal of Mathematics and Mathematical Sciences, Volume 13, Issue 1, Page 205-206, 1990., 1989 The k‐domination number of a graph G = G(V, E), γk(G), is the least cardinality of a set X ⊂ V such that any vertex in VX is adjacent to at least k vertices of X. Extending a result of Cockayne, Gamble and Shepherd [4], we prove that if , n ≥ 1, k ≥ 1 then, , where p is the order of G.
Y. Caro, Y. Roditty
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On some interconnections between combinatorial optimization and extremal graph theory [PDF]
, 2004 The uniting feature of combinatorial optimization and extremal graph theory is that in both areas one should find extrema of a function defined in most cases on a finite set.
Cvetković Dragoš M. +2 more
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On the discrepancy of coloring finite sets
International Journal of Mathematics and Mathematical Sciences, Volume 13, Issue 4, Page 825-827, 1990., 1990 Given a subset S of {1, …, n} and a map X : {1, …, n} → {−1, 1}, (i.e. a coloring of {1, …, n} with two colors, say red and blue) define the discrepancy of S with respect to X to be dX(S)=|∑i∈SX(i)| (the difference between the reds and blues on S).
D. Hajela
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A regular graph of girth 6 and valency 11
International Journal of Mathematics and Mathematical Sciences, Volume 9, Issue 3, Page 561-565, 1986., 1986 Let f(11, 6) be the number of vertices of an (11, 6)‐cage. By giving a regular graph of girth 6 and valency 11, we show that f(11, 6) ≤ 240. This is the best known upper bound for f(11, 6).
P. K. Wong
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A note on the problem of finding a (3, 9)‐cage
International Journal of Mathematics and Mathematical Sciences, Volume 8, Issue 4, Page 817-820, 1985., 1985 In this paper, we discuss The poblem of finding a (3, 9)‐cage. A hamiltonian graph with girth 9 and 54 vertices is given. Except four vertices, each of the remaining vertices of this graph has valency Three. This graph is obtained with the aid of a computer.
P. K. Wong
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International Journal of Mathematics and Mathematical Sciences, Volume 5, Issue 3, Page 553-564, 1982., 1982 A graph is subeulerian if it is spanned by an eulerian supergraph. Boesch, Suffel and Tindell have characterized the class of subeulerian graphs and determined the minimum number of additional lines required to make a subeulerian graph eulerian. In this paper, we consider the related notion of a subsemi‐eulerian graph, i.e.
Charles Suffel +3 more
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On extremal numbers of the triangle plus the four-cycle
Forum of Mathematics, SigmaFor a family $\mathcal {F}$ of graphs, let ${\mathrm {ex}}(n,\mathcal {F})$ denote the maximum number of edges in an n-vertex graph which contains none of the members of $\mathcal {F}$ as a subgraph.
Jie Ma, Tianchi Yang
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Hyper-Wiener indices of polyphenyl chains and polyphenyl spiders
Open Mathematics, 2019 Let G be a connected graph and u and v two vertices of G. The hyper-Wiener index of graph G is WW(G)=12∑u,v∈V(G)(dG(u,v)+dG2(u,v))$\begin{array}{} WW(G)=\frac{1}{2}\sum\limits_{u,v\in V(G)}(d_{G}(u,v)+d^{2}_{G}(u,v)) \end{array}$, where dG(u, v) is the ...
Wu Tingzeng, Lü Huazhong
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Exact solutions to the Erdős-Rothschild problem
Forum of Mathematics, SigmaLet $\boldsymbol {k} := (k_1,\ldots ,k_s)$ be a sequence of natural numbers. For a graph G, let $F(G;\boldsymbol {k})$ denote the number of colourings of the edges of G with colours $1,\dots ,s$ such that, for every $c \in \{1 ...
Oleg Pikhurko, Katherine Staden
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On the Metric Dimension of Directed and Undirected Circulant Graphs
Discussiones Mathematicae Graph Theory, 2020 The undirected circulant graph Cn(±1, ±2, . . . , ±t) consists of vertices v0, v1, . . . , vn−1 and undirected edges vivi+j, where 0 ≤ i ≤ n − 1, 1 ≤ j ≤ t (2 ≤ t ≤ n2{n \over 2} ), and the directed circulant graph Cn(1, t) consists of vertices v0, v1, .
Vetrík Tomáš
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