Skip to main content

extend a continuous map on sphere to ball such that the image is out of a compact set

Let $\phi: S^{k-1}\to H\setminus Q$ be a continuous map, here

  • $E$ is an infinite dimensional Hilbert space
  • $Q$ is a compact set in $E$

I need extend $\phi$ to $B^{k}$ such that $\phi: B^{k}\to E\setminus Q$ is still continuous.

If $Q := \{u\in E:\|u\|_E=1\}\setminus E_{k+1}~ \text{where}~ E_{k+1} ~\text{is any $k+1$-dimension subspace of} ~E$ , that's Ok, how about other $Q$?

sorrymaker
  • 705
  • 3
  • 14