Let
X, Y be two locally compact Hausdorff spaces and
T:C_0(X)\rightarrow C_0(Y) be a standard surjective ɛ-norm-additive map, i.e.
\begin{equation*}\big|\|T(f)+T(g)\|-\|f+g\|\big|\leq \varepsilon,\;{\rm for\;all}\; f, g\in C_0(X).\end{equation*}
Then there exist a homeomorphism
\varphi:Y\rightarrow X and a continuous function
\lambda:Y\rightarrow\lbrace\pm1\rbrace such that
\begin{equation*}|T(f)(y)-\lambda(y)f(\varphi(y))|\leq\frac{3}{2}\varepsilon,\;{\rm for\;all}\;y\in Y,\;f\in C_0(X).\end{equation*}
The estimate ‘
\frac{3}{2}\varepsilon’ is optimal. And this result can be regarded as a new nonlinear extension of the Banach–Stone theorem.