Combination Theorem for Continuous Mappings/Normed Division Ring/Inverse Rule

Theorem
Let $\struct{S, \tau}$ be a topological space.

Let $\struct{R, +, *, \norm{\,\cdot\,}}$ be a normed division ring.

Let $\tau_R$ be the topology induced by the norm $\norm{\,\cdot\,}$.

Let $g : \struct{S, \tau} \to \struct{R, \tau_R}$ be continuous mappings.

Let $U = S \setminus \set{x : \map g x = 0}$

Let $g^{-1} : U \to R$ denote the mapping defined by:
 * $\forall x \in U : \map {g^{-1}} x = \map g x^{-1}$

Let $\tau_U$ be the subspace topology on $U$.

Then:
 * $g^{-1} : \struct{U, \tau_U} \to \struct{R, \tau_R}$ is continuous.

where $g^{-1} : U \to R$ is the mapping defined by:
 * $\forall x \in U : \map {g^{-1}} x = \map g x^{-1}$