Syntax

Syntactic actants

Actant 1: whose waist it is
(a) Genitive
(b) Possessive
Талия девушки была тонкая и гибкая. The girl's waist was thin and lithe.
Красивый пояс перехватывал её талию. A pretty belt encircled her waist.
NB When the word талия functions as a subject and does not have a descriptive modifier, the construction талия у + Genitive is often preferred to (a) and (b), above:
Талия у девушки была тонкая и гибкая. The girl's waist was thin and lithe.