By introducing the notions of L-spaces and L_r-spaces, a complete generalization of Kalton's closed graph theorem is obtained. It points out the class of L_r-spaces is the maximal class of range spaces for the clo...By introducing the notions of L-spaces and L_r-spaces, a complete generalization of Kalton's closed graph theorem is obtained. It points out the class of L_r-spaces is the maximal class of range spaces for the closed graph theorem when the class of domain spaces is the class of Mackey spaces with weakly * sequentially complete dual.Some examples are constructed showing that the class of L_r-spaces is strictly larger than the class of separable B_r-complete spaces.Some properties of L-spaces and L_r-spaces are discussed and the relations between B-complete (resp. B_r-complete) spaces and L-spaces (resp. L_r-spaces) are given.展开更多
Gyllenberg and Yan(Discrete Contin Dyn Syst Ser B 11(2):347–352,2009)presented a system in Zeeman’s class 30 of 3-dimensional Lotka-Volterra(3D LV)competitive systems to admit at least two limit cycles,one of which ...Gyllenberg and Yan(Discrete Contin Dyn Syst Ser B 11(2):347–352,2009)presented a system in Zeeman’s class 30 of 3-dimensional Lotka-Volterra(3D LV)competitive systems to admit at least two limit cycles,one of which is generated by the Hopf bifurcation and the other is obtained by the Poincaré-Bendixson theorem.Yu et al.(J Math Anal Appl 436:521–555,2016,Sect.3.4)recalculated the first Liapunov coefficient of Gyllenberg and Yan’s system to be positive,rather than negative as in Gyllenberg and Yan(2009),and pointed out that the Poincaré-Bendixson theorem is not applicable for that system.Jiang et al.(J Differ Equ 284:183–218,2021,p.213)proposed an open question:“whether Zeeman’s class 30 can be rigorously proved to admit at least two limit cycles by the Hopf theorem and the Poincaré-Bendixson theorem?”This paper provides four systems in Zeeman’s class 30 to admit at least two limit cycles by the Hopf theorem and the Poincaré-Bendixson theorem and gives an answer to the above question.展开更多
P-集合(packet sets)是把动态特性引入到有限普通集合(Cantor set)内,以改进有限普通集合而提出的。P-集合具有动态特性。P-集合是由内P-集合XF-(internal packet set XF-)与外P-集合XF(outer packet set XF)构成的集合对。利用P-集合,...P-集合(packet sets)是把动态特性引入到有限普通集合(Cantor set)内,以改进有限普通集合而提出的。P-集合具有动态特性。P-集合是由内P-集合XF-(internal packet set XF-)与外P-集合XF(outer packet set XF)构成的集合对。利用P-集合,提出内P-等价类、外P-等价类、P等价类的概念;给出P-等价类还原定理、内P-等价类离散区间内点定理、外P-等价类离散区间外点定理、P-等价类离散区间子区间定理、P-等价类辨识准则;利用这些结果给出P-等价类在未知信息搜索-辨识中的应用。结果表明,P-集合与普通集合之间存在交叉、渗透空间,一些新结果潜藏在这个空间中。展开更多
文摘By introducing the notions of L-spaces and L_r-spaces, a complete generalization of Kalton's closed graph theorem is obtained. It points out the class of L_r-spaces is the maximal class of range spaces for the closed graph theorem when the class of domain spaces is the class of Mackey spaces with weakly * sequentially complete dual.Some examples are constructed showing that the class of L_r-spaces is strictly larger than the class of separable B_r-complete spaces.Some properties of L-spaces and L_r-spaces are discussed and the relations between B-complete (resp. B_r-complete) spaces and L-spaces (resp. L_r-spaces) are given.
基金the National Natural Science Foundation of China(NSFC)under Grant No.12171321.
文摘Gyllenberg and Yan(Discrete Contin Dyn Syst Ser B 11(2):347–352,2009)presented a system in Zeeman’s class 30 of 3-dimensional Lotka-Volterra(3D LV)competitive systems to admit at least two limit cycles,one of which is generated by the Hopf bifurcation and the other is obtained by the Poincaré-Bendixson theorem.Yu et al.(J Math Anal Appl 436:521–555,2016,Sect.3.4)recalculated the first Liapunov coefficient of Gyllenberg and Yan’s system to be positive,rather than negative as in Gyllenberg and Yan(2009),and pointed out that the Poincaré-Bendixson theorem is not applicable for that system.Jiang et al.(J Differ Equ 284:183–218,2021,p.213)proposed an open question:“whether Zeeman’s class 30 can be rigorously proved to admit at least two limit cycles by the Hopf theorem and the Poincaré-Bendixson theorem?”This paper provides four systems in Zeeman’s class 30 to admit at least two limit cycles by the Hopf theorem and the Poincaré-Bendixson theorem and gives an answer to the above question.
文摘P-集合(packet sets)是把动态特性引入到有限普通集合(Cantor set)内,以改进有限普通集合而提出的。P-集合具有动态特性。P-集合是由内P-集合XF-(internal packet set XF-)与外P-集合XF(outer packet set XF)构成的集合对。利用P-集合,提出内P-等价类、外P-等价类、P等价类的概念;给出P-等价类还原定理、内P-等价类离散区间内点定理、外P-等价类离散区间外点定理、P-等价类离散区间子区间定理、P-等价类辨识准则;利用这些结果给出P-等价类在未知信息搜索-辨识中的应用。结果表明,P-集合与普通集合之间存在交叉、渗透空间,一些新结果潜藏在这个空间中。
