An analogue of Fekete's lemma for subadditive functions on cancellative   amenable semigroups
  We prove an analogue of Fekete's lemma for subadditive right-subinvariant functions defined on the finite subsets of a cancellative left-amenable semigroup. This extends results previously obtained in the case of amenable groups by E. Lindenstrauss and B. Weiss and by M. Gromov. 
Tullio Ceccherini-Silberstein, Fabrice Krieger, and Michel Coornaert
math.GR math.DS