Abstract and Applied Analysis
Volume 6 (2001), Issue 7, Pages 381-400
doi:10.1155/S1085337501000719
Abstract
Let X
be a Banach space, V⊂X
is its subspace and U⊂X*. Given x∈X, we are looking for v∈V such
that u (v)=u (x)
for all u∈U and ‖v‖ ≤M‖x‖. In
this article, we study the restrictions placed on the constant M
as a function of X,V, and U.