review interfaces

docs/src/lib/interfaces.md

@@ -210,6 +210,17 @@ isempty(::AbstractCentrallySymmetricPolytope)
 
 A zonotope is a specific centrally symmetric polytope characterized by a
 center and a collection of generators.
+Mathematically, a zonotope is defined as the set
+
+```math
+Z = \\left\\{ c + ∑_{i=1}^p ξ_i g_i,~~ ξ_i \\in [-1, 1]~~ ∀ i = 1,…, p \\right\\},
+```
+where ``c \\in \\mathbb{R}^n`` is its center and ``\\{g_i\\}_{i=1}^p``,
+``g_i \\in \\mathbb{R}^n``, is the set of generators.
+This characterization defines a zonotope as the finite Minkowski sum of line
+segments.
+Zonotopes can be equivalently described as the image of a unit infinity-norm
+ball in ``\\mathbb{R}^n`` by an affine transformation.
 
 ```@docs
 AbstractZonotope