On the third cohomology group of commutative monoids
  We interpret Grillet's symmetric thrid cohomology classes of commutative monoids in terms of strictly symmetric monoidal abelian groupoids. We state and prove a classification result that generalizes the well-known one for strictly commutative Picard categories by Deligne and Fr\"ohlich and Wall, and Sinh. 
Mar\'ia Calvo-Cervera, Antonio M. Cegarra, Benjam\'in A. Heredia
math.KT math.CT