Lattice theory
A complete lattice (L?????? is a set L with a partial
- transitive: l1 l2 l2 l3 l1 l3
- anti-symmetric: l1 l2 l2 l1 l1 = l2
and such that all subsets Y have least upper bounds Y:
- upper bound: ?l ? Y????l Y
- least: if ?l ? Y????l l0 then Y l0