sentences:  Skew lattices in rings and normal skew lattices are examples
  of algebras on this variety.Let formula_160 with formula_38, formula_39 and formula_163, formula_164 be the coset bijection from formula_165 to formula_166 taking formula_41 to formula_42, formula_169 be the coset bijection from formula_166 to formula_171 taking formula_42 to formula_46 and finally formula_174 be the coset bijection from formula_165 to formula_171 taking formula_41 to formula_46.A skew lattice formula_17 is categorical if one always has the equality formula_180, i.e.