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21.
Harris Kwong 《Discrete Mathematics》2008,308(23):5522-5532
Let G be a graph with vertex set V and edge set E, and let A be an abelian group. A labeling f:V→A induces an edge labeling f∗:E→A defined by f∗(xy)=f(x)+f(y). For i∈A, let vf(i)=card{v∈V:f(v)=i} and ef(i)=card{e∈E:f∗(e)=i}. A labeling f is said to be A-friendly if |vf(i)−vf(j)|≤1 for all (i,j)∈A×A, and A-cordial if we also have |ef(i)−ef(j)|≤1 for all (i,j)∈A×A. When A=Z2, the friendly index set of the graph G is defined as {|ef(1)−ef(0)|:the vertex labelingf is Z2-friendly}. In this paper we completely determine the friendly index sets of 2-regular graphs. In particular, we show that a 2-regular graph of order n is cordial if and only if n?2 (mod 4). 相似文献
22.
Disjoint triangles and quadrilaterals in a graph 总被引:1,自引:0,他引:1
Jin Yan 《Discrete Mathematics》2008,308(17):3930-3937
Let G be a simple graph of order n and s and k be two positive integers. Brandt et al. obtained the following result: If s?k, n?3s+4(k-s) and σ2(G)?n+s, then G contains k disjoint cycles C1,…,Ck satisfying |Ci|=3 for 1?i?s and |Ci|?4 for s<i?k. In the above result, the length of Ci is not specified for s<i?k. We get a result specifying the length of Ci for each s<i?k if n?3s+4(k-s)+3. 相似文献
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李云章 《数学物理学报(B辑英文版)》2004,24(4):569-576
Let M=(11 1-1).In this paper, a necessary condition and an optimal sufficient condition on the orthogonality of M-wavelets are obtained by the introduction of cycle relat to M. 相似文献
26.
The star graph is one of the most attractive interconnection networks. The cycle embedding problem is widely discussed in many networks, and edge fault tolerance is an important issue for networks since edge failures may occur when a network is put into use. In this paper, we investigate the cycle embedding problem in star graphs with conditional faulty edges. We show that there exist fault-free cycles of all even lengths from 6 to n! in any n-dimensional star graph Sn (n ? 4) with ?3n − 10 faulty edges in which each node is incident with at least two fault-free edges. Our result not only improves the previously best known result where the number of tolerable faulty edges is up to 2n − 7, but also extends the result that there exists a fault-free Hamiltonian cycle under the same condition. 相似文献
27.
By the explicit representation for the divided differences with repetitions involving cycle index of symmetric groups, this paper deals with the asymptotic behavior of the intermediate point of the mean value theorem of divided differences with repetitions. Our results generalize some recent interesting results such as the asymptotic expansions of the immediate points of the Taylor formula and the differential mean value theorem of divided differences with distinct points. 相似文献
28.
Florian Pfender 《Discrete Mathematics》2009,309(9):2922-2924
We show that line graphs G=L(H) with σ2(G)≥7 contain cycles of all lengths k, 2rad(H)+1≤k≤c(G). This implies that every line graph of such a graph with 2rad(H)≥Δ(H) is subpancyclic, improving a recent result of Xiong and Li. The bound on σ2(G) is best possible. 相似文献
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