Differentiability of the isoperimetric profile and topology of analytic   Riemannian manifolds
  We show that smooth isoperimetric profiles are exceptional for real analytic Riemannian manifolds. For instance, under some extra assumption, this can happen only on topological spheres. 
Renata Grimaldi (DMMM), Stefano Nardulli (DMMM, LM-Orsay), Pierre   Pansu (LM-Orsay)
math.DG