The problem of invariance and self-similarity in Z-modules is investigated.
For a selection of examples relevant to quasicrystals, especially Fibonacci
modules, we determine the semigroup of self-similarities and encapsulate the
number of similarity submodules in terms of Dirichlet series generating
functions.Comment: 7 pages; to appear in: Aperiodic 97, eds. M. de Boissieu, J. L.
Verger-Gaugry and R. Currat, World Scientific, Singapore (1998), in pres