  This note discusses two problems related to the Fredrickson-Andersen one spin
facilitated model in stationarity. The first, considered in 2008 in a paper of
Cancrini, Martinelli, Roberto and Toninelli, is the spectral gap of the model's
infinitesimal generator. They study the decay of this spectral gap when the
density is large, but in dimensions $3$ and higher, they do not find the exact
exponent. They also show that the persistence function of the model has
exponential tail, but the typical decay time is not analyzed. We will see that
the correct exponent for the decay of the spectral gap in dimension $3$ and
higher is $2$, and discover how the time over which the persistence function
decays diverges in high densities. We also discuss the scaling of the spectral
gap in finite graphs.
