Holomorphic functions with Nash real part
Antonio Carbone
TL;DR
This work resolves the question of when a holomorphic function on an open set $D\subset \mathbb{C}^n$ is complex Nash by tying it to the Nash-ness of its real (or imaginary) part. The authors prove that $f=f_1+i f_2$ is complex Nash if and only if $f_1$ (and equivalently $f_2$) is real Nash, using a combination of real–complex algebraic techniques and a Cartan-type construction to reconstruct $f$ from its real part. Key contributions include establishing the equivalence of $f\in \mathcal{N}_{\mathbb{C}}(D)$ with $f_1,f_2\in \mathcal{N}_{\mathbb{R}}(D)$, and providing a self-contained proof that avoids reliance on integration. The results clarify the algebraic structure of Nash holomorphic functions and have implications for definability and algebraicity in several complex variables.
Abstract
In this paper we show that a holomorphic function, defined on an open subset $D$ of $\mathbb{C}^n$, is a complex Nash function if and only if its real part (or equivalently its imaginary part) is a real Nash function.
