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An edge cut X of a connected graph G is a k-restricted edge cut if G-X is disconnected and every component of G-X has at least k vertices. Additionally, if the deletion of a minimum k-restricted edge cut isolates a connected component of k vertices, then the graph is said to be super-λk. In this paper, several sufficient conditions yielding super-λk graphs are given in terms of the girth and the diameter. 相似文献
74.
Mei-Chu Chang 《Journal of Functional Analysis》2004,207(2):444-460
A well-known conjecture of W. Rudin is that the set of squares is a ∧p-set for all p>4. In particular, this implies that for all ε>0, there exists a constant cε such that
75.
Takayoshi FujiiShinsuke Asai Tomoyuki OkadaWei Hao Hiroyuki MoritaToshiaki Yoshimura 《Tetrahedron letters》2003,44(33):6203-6205
Several diaryl(fluoro)-λ6-sulfanenitriles 3 were synthesized by the reaction of S,S-diarylsulfimides 1 with Selectfluor™. This reaction also allows the first preparation of heterocyclic fluoro-λ6-sulfanenitrile, 5-fluoro-10,10-dioxo-5,10-dihydro-5λ6,10λ6-thianthren-5-nitrile (5) and its molecular structure was determined by X-ray crystallographic analysis. 相似文献
76.
基于(λ,μ)-反模糊子群概念及其基本性质,深入刻画了(λ,μ)-反模糊子群以及(λ,μ)-反模糊正规子群的结构.首先讨论了群G的(λ,μ)-反模糊子群在G的不同元素上隶属度的分布情况,其次研究了(λ,μ)-反模糊正规子群在G的不同元素上隶属度的分布情况,最后对循环群和阿贝尔群上(λ,μ)-反模糊子群及正规子群的结构进行详细讨论并给出了相应的结果. 相似文献
77.
Jiangang Qi 《Journal of Mathematical Analysis and Applications》2007,334(2):983-997
Some limit-point criteria are obtained for higher-dimensional semi-degenerate singular Hamiltonian differential systems with perturbation potential terms by using M(λ)-theory. Results in this paper cover many previous results of Hartman, Levinson, Titchmarsh and Read. 相似文献
78.
Nazli Jalalian 《Tetrahedron》2010,66(31):5793-11780
The application of chiral hypervalent iodine reagents in asymmetric synthesis is highly desirable, as the reagents are metal-free, environmentally benign and employed under mild conditions. Three chiral diaryliodonium salts have been designed to provide chemoselectivity and asymmetric induction in asymmetric α-phenylation of carbonyl compounds. The synthetic routes to the selected targets are detailed herein, together with a structural investigation into the diastereoselectivity of the alkylation process. 相似文献
79.
Yurii V. Svyaschenko 《Tetrahedron letters》2010,51(48):6316-6318
A novel approach to 1,2λ5-azaphosphinines has been elaborated. Aminophosphonium chlorides bearing a β-dialkylaminocrotonic nitrile residue react with N,N-dimethylformamide dimethylacetal to afford 1,2λ5-azaphosphinines. 相似文献
80.