unconditionally convergent series

In normed space with limited dimension and infinite dimensional Fréche space,unconditional convergence of series is equivalent with absolute convergence.

文中讨论了无穷维赋范线性空间中,级数的收敛、绝对收敛、条件收敛、无条件收敛、弱无条件收敛等概念之间的关系,且通过反例说明弱无条件收敛的级数未必收敛、无条件收敛的级数未必绝对收敛等重要结论。

It is discussed that the relations between the convergence, absolute convergence, weakly unconditional convergence and unconditional convergence and summability of an infinite series ∑∞n=1x_nin a Banach space X.

研究了Banach空间X中的级数∑∞n=1xn的收敛性、绝对收敛性、弱无条件收敛性、无条件收敛性与可和性等概念之间的关系,证明了:当X为一般Banach空间时,无条件收敛性与可和性是等价的;当X为Hilbert空间时,弱无条件收敛性、无条件收敛性及可和性是等价的;当X为数域时,无条件收敛性与绝对收敛性及可和性是等价的。