The cones of Hilbert functions of squarefree modules
  In this paper, we study different generalizations of the notion of squarefreeness for ideals to the more general case of modules. We describe the cones of Hilbert functions for squarefree modules in general and those generated in degree zero. We give their extremal rays and defining inequalities. For squarefree modules generated in degree zero, we compare the defining inequalities of that cone with the classical Kruskal-Katona bound, also asymptotically. 
Cristina Bertone, Dang Hop Nguyen, Kathrin Vorwerk
math.AC