A-hypergeometric series and the Hasse-Witt matrix of a hypersurface
  We give a short combinatorial proof of the generic invertibility of the Hasse-Witt matrix of a projective hypersurface. We also examine the relationship between the Hasse-Witt matrix and certain $A$-hypergeometric series, which is what motivated the proof. 
Alan Adolphson and Steven Sperber
math.AG