If a ball is the union of two sets, does one of them non empty interior?

63 Views Asked by At

Hi everyone: Suppose that an open ball $B$ of $\mathbb{R}^{m}$ $(m\geq2)$ can be written as the disjoint union of two sets: $B=E\cup F$. Can we conclude that one these sets,$E$ or $F$, has non empty interior? Thanks for you reply.