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半覆盖远离性与有限群的结构 被引量:2
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作者 郭秀云 崔雅琼 《上海大学学报(自然科学版)》 CAS CSCD 北大核心 2008年第3期244-247,共4页
利用Sylow子群的极大子群或者具有半覆盖远离性或者半正规,给出了有限群为超可解群的一些充分条件,推广了几个已有的结果.
关键词 覆盖远离 半正规性 超可解
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P_k γ上理想的若干性质
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作者 张平 《扬州师院学报(自然科学版)》 CSCD 1996年第2期1-6,共6页
证明了:1)P_κλ上存在一个半正规,弱选择,但不是λ-生成的理想.2)若 I 是一个λ^(<κ)-生成的,κ-完全的,弱选择的理想,则对每一个 A∈I^+,都存在 B∈P(A)∩I^+,使得 I|B=I_κλ|B;若 I 是一个λ^(<κ)-生成的,κ-完全的,弱选择... 证明了:1)P_κλ上存在一个半正规,弱选择,但不是λ-生成的理想.2)若 I 是一个λ^(<κ)-生成的,κ-完全的,弱选择的理想,则对每一个 A∈I^+,都存在 B∈P(A)∩I^+,使得 I|B=I_κλ|B;若 I 是一个λ^(<κ)-生成的,κ-完全的,弱选择的正规理想,则对每个 A∈I^+,都存在μ<κ,使得 I|A 不是(μ,λ)-可分的.3)若 Q_κλ上存在一个精细,■κ正规理想,则 P_κλ上存在一个精细,具有■κ性质的理想. 展开更多
关键词 集合 理想 半正规性 弱选择
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On Ws-Regular Spaces
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作者 Halgwrd Mohammed Darwesh Adil Kadir Jabbar 《Journal of Mathematics and System Science》 2012年第2期67-71,共5页
In the present, the authors investigate a new type of separation axioms, which they call it w s-regular. The authors obtained some of its basic properties and its characterizations. Also, the authors notice that the a... In the present, the authors investigate a new type of separation axioms, which they call it w s-regular. The authors obtained some of its basic properties and its characterizations. Also, the authors notice that the axiom of tO s-regularity is weaker than the regularity, stronger than s-regularity and it is independent of w -regularity. However, the authors showed that the w s-regularity and regularity are identical on the class of all locally countable spaces, while the concepts ofw s-regularity and s-regularity are same on the class of anti-locally countable spaces:; furthermore, they proved that the three concepts w s-regularity, s-regularity and w s-regularity are same on the class of extremally disconnected spaces. The authors characterized w s-regular Trspaces by g-open sets, and they proved that the w s-regularity is an open hereditary property and it is also a topologizal property. The w s-closure of subsets of topological spaces are investigated and characterized. The authors used the concepts w s-closure to obtain some characterizations of the w s-regular spaces. Behind those, the authors obtained some properties and characterizations of w -semi open sets. 展开更多
关键词 Semi-open set w -semi open set regular space s-regular space w s-regular space locally and anti locally countable space extremally disconnected space.
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Samuel multiplicity and the structure of essentially semi-regular operators: A note on a paper of Fang
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作者 ZENG QingPing ZHONG HuaiJie WU ZhenYing 《Science China Mathematics》 SCIE 2013年第6期1213-1231,共19页
Motivated by a paper of Fang (2009), we study the Samuel multiplicity and the structure of essentially semi-regular operators on an infinite-dimensional complex Banach space. First, we generalize Fang's results co... Motivated by a paper of Fang (2009), we study the Samuel multiplicity and the structure of essentially semi-regular operators on an infinite-dimensional complex Banach space. First, we generalize Fang's results concerning Samuel multiplicity from semi-Fredholm operators to essentially semi-regular operators by elementary methods in operator theory. Second, we study the structure of essentially semi-regular operators. More precisely, we present a revised version of Fang's 4 × 4 upper triangular model with a little modification, and prove it in detail after providing numerous preliminary results, some of which are inspired by Fang's paper. At last, as some applications, we get the structure of semi-Fredholm operators which revised Fang's 4 × 4 upper triangular model, from a different viewpoint, and characterize a semi-regular point λ∈ C in an essentially semi-regular domain. 展开更多
关键词 samuel multiplicity essentially semi-regular operators semi-Fredholm operators semi-regularoperators Kato decomposition
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