Compactifications on twisted tori with fluxes and free differential   algebras
  We describe free differential algebras for non-abelian one and two form gauge potentials in four dimensions deriving the integrability conditions for the corresponding curvatures. We show that a realization of these algebras occurs in M-theory compactifications on twisted tori with constant four-form flux, due to the presence of antisymmetric tensor fields in the reduced theory. 
Gianguido Dall'Agata, Riccardo D'Auria and Sergio Ferrara