In this talk we show that the Dirichlet Laplacian on a
periodically perforated domain (compact or not) converges to a
homogenised limit when the period lengths tends to 0.  Classically, only
strong resolvent convergence has been shown. Using abstract methods for
convergence of operators acting in varying Hilbert spaces, we can also
show norm resolvent convergence.  This is a joint work with Andrii
Khrabustovskyi (KIT)