Relational Sheaves for a Heyting Algebra
  We show that for a Heyting algebra ${\cal H}$, a relational-presheaf is an idempotent symmetric order-preserving lax-semifunctor. A relational-presheaf is a relational-sheaf, if it is an idempotent infima-preserving lax semifunctor. The associated relational-sheaf functor factors through the category of sheaves for ${\cal H}$. Using this and the appropriate comparison theorems we obtain the main result that the associated categories of relational-presheaves and relational-sheaves are each respectively equivalent to the categories of presheaves and sheaves for ${\cal H}$. 
W. Dale Garraway
math.CT