Suppose that $K$ is a simply connected and closed subset of an infinite-dimensional Banach space $B$. Then is $K$ necessarily a retract of $B$?
I can't seem to find a counter example..
banach-spacesgeneral-topologytopological-vector-spaces
Suppose that $K$ is a simply connected and closed subset of an infinite-dimensional Banach space $B$. Then is $K$ necessarily a retract of $B$?
I can't seem to find a counter example..
Best Answer
Each Banach space is contractible.
Each retract of a contractible space is contractible.
Each Banach space of dimension $> 1$ contains a compact simply connected subset which is not contractible.