CONSTRUCTING OPERATORS WHICH CANNOT BE ISOMETRICALLY APPROXIMATED

Let E, F be Banach spaces. Suppose T∈B(E, F) to be an ε-isometric operator, i.e. We say that {T_ε|0≤ε<1} admits the isometry approximation     

A REMARK ON _1 SUBSPACES OF L_1 (μ,X)

ＡＲＥＭＡＲＫＯＮ　_1　ＳＵＢＳＰＡＣＥＳＯＦＬΦ_１（μ，Ｘ）ＤｉｎｇＧｕａｎｇｇｕｉ（定光桂）；ＨｕａｎｇＳｅｎｚｈｏｎｇ（黄森忠）（ＤｅｐａｒｔｍｅｎｔｏｆＭａｔｈｅｍａｔｉｃｓ，ＮａｎｋａｉＵｎｉｖｅｒｓｉｔｙ，Ｔｉａｎｊｉｎ３０００７１，...     

关于疾控成本最优策略问题的建模及求解

本文是本作者和合作者最近工作的一个综述.考虑实际情况下的如下成本问题:是维持现有的控制度("持平"),还是加强控制力度("走高"),何种策略在疾控成本上最优?文献[1]给出的答案是:这依赖于平均治疗费用和平均预防费用的比值.特别地,若这个比值大于1,则成本最优的控制策略是"走高".此外,文献[1]的结果表明,有限时间里的成本最优控制策略可能会是个Bang-Bang型的.     

重新赋范与等距逼近问题

本文考虑等距逼近问题。首先研究建立等距逼近问题的一般研究方法的可能性。得出的结论是:不存在一般的方法。其次研究本文里引进的所谓B型空间。得到一些初步的结果。     

APPROXIMATE ISOMETRIES ON (F)-NORMED SPACES

By considering the connection of approximate isometry with isometry we study the following problem "For what subclass of (F)-normed spaces the metric structure completely determines the linear constructure and further, what form can be taken when we represent an approximate isomaetry as a perturbation of isometry. We introduce a subclass of so-called midpoint p-constracted (F)-normed spaces. For this subclass some new results are obtained and especially the known results of Mazur-Ulam and Gervitz-Gruber are extended.     

AL_p空间(O

黄森忠 《数学学报》1987,30(4):455-466