研究了Banach空间中的Xd-Bessel列的一些性质,证明了当Xd为BK-空间时,BX(Xd)和B(X,Xd)等距同构,由此得到BX(Xd)是Banach空间.当Xd是以{ei}i∈Λ为无条件基的自反BK-空间时,得到了Xd-Bessel列的一些等价刻画.
Some properties of Xd-Bessel sequences for a Banach space is discussed.It is proved that when Xd is a BK-space,BX(Xd) is isometrically isomorphic with B(X,Xd) which means BX(Xd) is a Banach space.When Xd is a reflecxive BK-space with the basis{ei}i∈Λ,then some equivalent characterizations of Xd-Bessel sequences for a Banach space X are given.