A short proof of a central limit theorem for the order of the giant component and $k$-core

In this note we outline a new and simple approach to proving central limit theorems for various ‘global’ graph parameters which have robust ‘local’ approximations, using the Efron–Stein inequality, which relies on a combinatorial analysis of the stability of these approximations under resampling an edge. As an application, we give short proofs of a central limit theorem for the order of the giant component and of the $k$-core for sparse random graphs.