The Lattice of Fuzzy Intervals and Sufficient Conditions for its   Distributivity
  Given a reference lattice, we define fuzzy intervals to be the fuzzy sets such that their p-cuts are crisp closed intervals. We show that: given a complete reference lattice, the collection of its fuzzy intervals is a complete lattice. Furthermore we show that: if the reference lattice is completely distributive then the lattice of its fuzzy intervals is distributive. 
Ath. Kehagias