The author shows a characterization of a (unbounded) weakly filter convergent sequence which is parallel to that every weakly null sequence (xn) in a Banach space admits a norm null sequence (yn) with yn ∈ co...The author shows a characterization of a (unbounded) weakly filter convergent sequence which is parallel to that every weakly null sequence (xn) in a Banach space admits a norm null sequence (yn) with yn ∈ co(xk)k≥n for all n ∈ N. A version of the Radon-Riesz type theorem is also proved within the frame of the filter convergence.展开更多
基金partially supported by the Natural Science Foundation of China(11426061,11501108)the Natural Science Foundation of Fujian province(2015J01579)
文摘The author shows a characterization of a (unbounded) weakly filter convergent sequence which is parallel to that every weakly null sequence (xn) in a Banach space admits a norm null sequence (yn) with yn ∈ co(xk)k≥n for all n ∈ N. A version of the Radon-Riesz type theorem is also proved within the frame of the filter convergence.