Let $f,g$ be a pair of univalent functions on a proper subdomain $\Omega$ of $\mathbb C$. Does their sum $f+g$ necessarily omit any complex value?
Similarly, can all holomorphic function be written as sums of univalent functions?

No to both in as simple domain as the unit disk. 1) $(1-z)^{-2}-(1+z)^{-2}$ 2) Univalent functions cannot grow too fast near the boundary.
– fedjaJun 16 '12 at 0:36

Or $z$ and $1/z$ on ${\bf C} - \{0\}$.
– Nik WeaverJun 16 '12 at 0:42

`$z$`

and`$1/z$`

on`${\bf C} - \{0\}$`

. – Nik Weaver Jun 16 '12 at 0:42