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991.
992.
研究了一类参数方程的曲线,其参变量表示为所谓时标(time scale),该时标是所有实数的集的一个任意闭子集.引入了相应于矢量场的方向导数. 相似文献
993.
乔占科 《数学的实践与认识》2006,36(8):342-344
研究了拟正则半环上的同余,给出了拟正则半环上一类理想的性质,并利用这类理想给出了拟正则半环上可除半环同余的几种等价形式. 相似文献
994.
FAN Hongbing LIU Guizhen & LIU Jiping Department of Physics Computer Science Wilfrid Laurier University Waterloo ON. NL C Canada School of Mathematics System Science Shandong University Jinan China Department of Mathematics Computer Science University of Lethbridge Lethbridge AB. TK M Canada 《中国科学A辑(英文版)》2006,49(2):158-172
A 2-graph is a hypergraph with edge sizes of at most two. A regular 2-graph is said to be minimal if it does not contain a proper regular factor. Let f2(n) be the maximum value of degrees over all minimal regular 2-graphs of n vertices. In this paper, we provide a structure property of minimal regular 2-graphs, and consequently, prove that f2(n) = n 3-i/3, where 1 ≤ i ≤ 6, i ≡ n (mod 6) and n ≥ 7, which solves a conjecture posed by Fan, Liu, Wu and Wong. As applications in graph theory, we are able to characterize unfactorable regular graphs and provide the best possible factor existence theorem on degree conditions. Moreover, fa(n) and the minimal 2-graphs can be used in the universal switch box designs, which originally motivated this study. 相似文献
995.
设S是一个正则半群,如果存在一个S的子半群S~*及上的一元运算*满足条件:(1)(?)x∈S,x~*∈S~*∩V(x);(2)(?)x∈S~*,(x~*)~*=x;(3)(?)x,y∈S,(x~*y)~*=y~*x~(**),(xy~*)~*=y~(xx)x~*则称S~*是S的一个正则*_-断面.本文刻画了具有正则*_-断面的正则半群的结构。 相似文献
996.
Camillo Costantini 《Proceedings of the American Mathematical Society》2005,133(6):1861-1864
We solve a problem of Padmavally about resolvability of locally connected spaces, in the case where the space under consideration is regular.
997.
本文研究纯正的群的正则带.在给出这类半群的若干特征后,建立了纯正的群的正则带的构造定理.作为应用,同时给出了纯正的群的右拟正规带的构造定理. 相似文献
998.
N. Yu. Makarenko 《Siberian Mathematical Journal》2005,46(6):1097-1107
We improve the conclusion in Khukhro's theorem stating that a Lie ring (algebra) L admitting an automorphism of prime order p with finitely many m fixed points (with finite-dimensional fixed-point subalgebra of dimension m) has a subring (subalgebra) H of nilpotency class bounded by a function of p such that the index of the additive subgroup |L: H| (the codimension of H) is bounded by a function of m and p. We prove that there exists an ideal, rather than merely a subring (subalgebra), of nilpotency class bounded in terms of p and of index (codimension) bounded in terms of m and p. The proof is based on the method of generalized, or graded, centralizers which was originally suggested in [E. I. Khukhro, Math. USSR Sbornik 71 (1992) 51–63]. An important precursor is a joint theorem of the author and E. I. Khukhro on almost solubility of Lie rings (algebras) with almost regular automorphisms of finite order. 相似文献
999.
The concept of a hemisystem of a generalised quadrangle has its roots in the work of B. Segre, and this term is used here to denote a set of points such that every line ℓ meets in half of the points of ℓ. If one takes the point-line geometry on the points of the hemisystem, then one obtains a partial quadrangle and hence a
strongly regular point graph. The only previously known hemisystems of generalised quadrangles of order (q, q
2) were those of the elliptic quadric , q odd. We show in this paper that there exists a hemisystem of the Fisher–Thas–Walker–Kantor generalised quadrangle of order
(5, 52), which leads to a new partial quadrangle. Moreover, we can construct from our hemisystem the 3· A
7-hemisystem of , first constructed by Cossidente and Penttila.
相似文献
1000.
Anna Draganova 《Czechoslovak Mathematical Journal》2009,59(1):51-60
For any nontrivial connected graph F and any graph G, the F-degree of a vertex v in G is the number of copies of F in G containing v. G is called F-continuous if and only if the F-degrees of any two adjacent vertices in G differ by at most 1; G is F-regular if the F-degrees of all vertices in G are the same. This paper classifies all P
4-continuous graphs with girth greater than 3. We show that for any nontrivial connected graph F other than the star K
1,k
, k ⩾ 1, there exists a regular graph that is not F-continuous. If F is 2-connected, then there exists a regular F-continuous graph that is not F-regular.
相似文献