I am trying to figure out if the statement holds true, the literature i am following says that its not true but i don't seem to understand,
If $Y$ is a Banach space and let subspace $A \subset Y'$, such that $Y'$ is a dual . $A$ is norm closed if and only if $A$ is weak star closed ?
Looks like reflexivity comes into play to argue this statement . Thank you for your hints !