Given $A \in \mathsf{M}_{m \times n}(\mathbb{R})$ and $b \in \mathbb{R}^m$, the polyhedron with respect to $A$ and $b$, denoted by $P(A,b)$, is defined by $$ \{ x \in \mathbb{R}^n \mid Ax \le b \}.$$ If $P(A,b)$ is compact, then $P(A,b)$ is called a polytope; if $b=0$, then $P(A,b)$ is called a polyhedral cone.
As is well-known, $P(A,b)$ is a polytope if and only if there are vectors $v_1,\dots,v_k \in \mathbb{R}^n$ such that $P(A,b) = \text{conv}(\{v_1,\dots,v_k\})$. Similary, $P(A,0)$ is polyhedral cone if and only if there are vectors $v_1,\dots,v_k \in \mathbb{R}^n$ such that $P(A,0) = \text{coni}(\{v_1,\dots,v_k\})$.
In $\mathbb{C}^n$, it seems reasonable to define a polytope and polyhderal cone as the convex hull and conical hull of a finite collection of vectors, respectively.
The map $f: \mathbb{C}^n \longrightarrow \mathbb{R}^{2n}$ defined by $$ \begin{bmatrix} z_1 \\ \vdots \\ z_n \end{bmatrix}\in\mathbb{C}^n \longmapsto \begin{bmatrix} \Re z_1 \\ \Im z_1 \\ \vdots \\ \Re z_n \\ \Im z_n \end{bmatrix} \in \mathbb{R}^{2n} $$ is a linear isomorphism (here $\mathbb{C}^n$ is viewed as a real, $2n$-dimensional vector space). With the definition above, $V$ is a polytope (respectively, polyhedral cone) in $\mathbb{C}^n$ if and only if $f(V)$ is a polytope (respectively, polyhedral cone) in $\mathbb{R}^{2n}$.
Questions:
- Have polytopes/convex polyhedra been defined this way in complex Euclidean space?
- Has this observation been made before?
- If so, is there a suitable reference?