共查询到20条相似文献,搜索用时 640 毫秒
1.
关于Z映射与局部连通空间的几个定理曹尚民(聊城师范学院,252059)定义1设X,Y为拓扑空间,若f:X→Y对于Y的任一开集V有f(Int(f ̄(-1)(v)))=v,则称f为z映射。定义2拓扑空间x的子集A称为Pre-open集,若和c1分别是集合... 相似文献
2.
3.
4.
5.
朱赋鎏 《数学物理学报(A辑)》1996,16(4):444-452
设X=G0/K0是非紧致黎曼对称空间,G0的李代数g0是其复化李代数g的正规实型.若记n0=dimX,则我们在该文中证明:对于f∈Lp(X),1≤P≤2,当复数z满足Rez>δ(n0,P)=(n0-1)(1/P—1/2)时,f关于拉普拉斯算子本征函数展开的z阶Riesz平均几乎处处收敛于f.这一结论与经典的欧氏空间,以及复的和一秩的非紧致黎曼对称空间中完全相同. 相似文献
6.
关于K—极凸Banach空间 总被引:3,自引:0,他引:3
何仁义 《纯粹数学与应用数学》1998,14(2):19-22
引进K-极凸Banach空间,证明了XK-极凸当且仅当X自反、K-严格凸且有(H)性质,得到了K-极凸空间的一些性质,并讨论了K-极凸与K-K-强光滑、K-一致凸及完全K-凸的关系。 相似文献
7.
本文证明了如下两个定理:(1)C_k(X)为强Frechet空间(或者Frechet空间)的充分必要条件是X中的每一开K-覆盖序列{u_n:n∈N},存在U_n∈u_n,使{U_n:n∈N}为X的K-序列,(2)C_k(X)有可数扇密度的充分必要条件是X中的每一开K-覆盖序列{u_n:n∈N}存在u_n的有限于族u'_n,使{u'_n:n∈N}是X的开K-覆盖. 相似文献
8.
薛留根 《数理统计与应用概率》1994,9(3):54-60
设(Xn)是R^1中的平稳,强混合序列,具有公共的密度f(x),则可定义f(x)及其导函数f^(r)(x)的核估计与最近邻估计f^(r)n(x)=(nh^r+1n(x))^-1n∑i=1K^(r)(Xi-X/hn(x)),fn(x)=(nan(x))^-1n∑i=1K(Xi-x/an(x))其中核函数K(X)为取定的概率密度函数,且具有r(r≥0)阶导数,窗宽hn(x)=hn(x;X1,...,X 相似文献
9.
10.
K-强凸性与K-强光滑性 总被引:14,自引:0,他引:14
苏雅拉图 《数学年刊A辑(中文版)》1998,(3)
本文引进了K-强凸性的概念,它是强凸性概念的推广.然后证明了K-强凸性与K-强光滑具有对偶性质;X为K-强光滑当且仅当X是自反且K-强凸;自反的Banach空间X是K-强凸当且仅当X是K-严格凸且具有(H)性质;局部K-一致凸空间是K-强凸的,从而推广了文[2-4]的结果.最后利用K-强暴露点的概念刻划了K-强光滑空间的特征,从而推广了[7]的结果. 相似文献
11.
12.
Huanyin CHEN Department of Mathematics Hunan Normal University Changsha China. 《数学年刊B辑(英文版)》2007,28(6):617-628
A ring R is a QB-ring provided that aR bR=R with a,b∈R implies that there exists a y∈R such that a by∈R_q~(-1).It is said that a ring R is a JB-ring provided that R/J(R)is a QB-ring,where J(R)is the Jacobson radical of R.In this paper,various necessary and sufficient conditions,under which a ring is a JB-ring,are established.It is proved that JB-rings can be characterized by pseudo-similarity.Furthermore,the author proves that R is a JB-ring iff so is R/J(R)~2. 相似文献
13.
14.
15.
This article proves a characterisation of the classical unital that is a generalisation of a characterisation proved in 1982
by Lefèvre-Percsy. It is shown that if is a Buekenhout-Metz unital with respect to a line in such that a line of not through meets in a Baer subline, then is classical. An immediate corollary is that if is a unital in PG such that is Buekenhout-Metz with respect to two distinct lines, then is classical.
Received 5 August 1999; revised 15 February 2000. 相似文献
16.
类似与标型谱算子,U-标算子是否拟仿射相似于自伴算子是一“公开问题”.尽管对具纯离散谱的U-标算子答案是肯定的,但一般情况下并不成立.本文继续探讨这一问题,证明了U-标算子在一强范数拓扑意义下是Hermite算子,或者说U-标算子拟仿射相似于Hermite算子,并给出U-标算子是标型谱算子的充要条件. 相似文献
17.
A. V. Zhuchok 《Algebra and Logic》2011,50(4):323-340
It is proved that a system of axioms for a dimonoid is independent and Cayley’s theorem for semigroups has an analog in the
class of dimonoids. The least separative congruence is constructed on an arbitrary dimonoid endowed with a commutative operation.
It is shown that an appropriate quotient dimonoid is a commutative separative semigroup. The least separative congruence on
a free commutative dimonoid is characterized. It is stated that each dimonoid with a commutative operation is a semilattice
of Archimedean subdimonoids, each dimonoid with a commutative periodic semigroup is a semilattice of unipotent subdimonoids,
and each dimonoid with a commutative operation is a semilattice of a-connected subdimonoids. Various dimonoid constructions are presented. 相似文献
18.
Goda Hiroshi; Hirasawa Mikami; Yamamoto Ryosuke 《Proceedings London Mathematical Society》2001,83(2):472-492
Let R be a Seifert surface obtained by applying Seifert's algorithmto a connected diagram D for a link L. In this paper, lettingD be almost alternating, we give a practical algorithm to determinewhether L is a fibered link and R is a fiber surface. We furthershow that L is a fibered link and R is a fiber surface for Lif and only if R is a Hopf plumbing, that is, a successive plumbingof a finite number of Hopf bands. It has been known for sometime that this is true if D is alternating, and we show thatit is not always true if D is 2-almost alternating. In the appendix,we partially answer C. Adams's open question concerning almostalternating diagrams. 2000 Mathematical Subject Classification:57M25. 相似文献
19.
环R称为N-环,如果R的素根N(R)={r∈R|存在自然数n使rn=0}.本文不仅对N-环进行了刻划,而且还研究了N-环的VonNeumann正则性.特别证明了:对于N-环R,如下条件是等价的:(1)R是强正则环;(2)R是正则环;(3)R是左SP-环;(4)R是右SF-环;(5)R是MELT,左p-V-环;(6)R是MERT,右p-V-环.因此推广了文献[4]中几乎所有的重要结果,同时也改进或推广了其它某些有关正则环的有用结果. 相似文献
20.
《Journal of Applied Mathematics and Mechanics》1999,63(2):305-312
Aero-elastic vibration is investigated in the case of a shallow shell of revolution or a cylindrical panel, which respectively occupy a part of a thin cylindrical body or a thin profile, in a high-velocity supersonic gas flow at zero angle of attack. Particular attention is paid to finding the pressure interaction and this problem is solved within the framework of the law of plane sections in boundary-layer theory. An expression is obtained which refines and supplements the well-known formula of “piston” theory. A linearized formulation of the problem of the panel flutter of a shallow shell is presented. Using the example of a plate located on one of the sides of a wedge, it is shown that the formula of “piston” theory is complemented with a term which has the meaning of a compressive force in the plane of the plate. It is shown that, when account is taken of this term, there is a reduction in the critical flow velocity. 相似文献