Published online by Cambridge University Press: 06 January 2022
We determine the asymptotics of the number of independent sets of size
$\lfloor \beta 2^{d-1} \rfloor$
in the discrete hypercube
$Q_d = \{0,1\}^d$
for any fixed
$\beta \in (0,1)$
as
$d \to \infty$
, extending a result of Galvin for
$\beta \in (1-1/\sqrt{2},1)$
. Moreover, we prove a multivariate local central limit theorem for structural features of independent sets in
$Q_d$
drawn according to the hard-core model at any fixed fugacity
$\lambda>0$
. In proving these results we develop several general tools for performing combinatorial enumeration using polymer models and the cluster expansion from statistical physics along with local central limit theorems.