Degenerate $C$-ultradistribution semigroups in locally convex spaces
  The main subject in this paper are degenerate $C$-ultradistribution semigroups in barreled sequentially complete locally convex spaces. Here, the regularizing operator $C$ is not necessarily injective and the infinitesimal generator is multivalued linear operator. We also consider exponential degenerate $C$-ultradistribution semigroups. 
Marko Kosti\'c, Stevan Pilipovi\'c and Daniel Velinov
math.FA