  This is an expository proof that, if $M$ is a compact $n$-manifold with no
boundary, then the set of holonomies of strictly-convex real-projective
structures on $M$ is a subset of
$\operatorname{Hom}(\pi_1M,\operatorname{PGL}(n+1,\mathbb RR))$ that is both
open and closed.
