sentences:  Returning to distribution, formula_158 so that formula_159 characterizes the variety of distributive, normal skew lattices, and (D3) characterizes the variety of symmetric, distributive, normal skew lattices.Categorical Skew Lattices
  
  A skew lattice is categorical if nonempty composites of coset bijections are coset bijections.Categorical skew lattices form a variety.