Lattices (Wikipedia) and are the most common forms of Abstract Domains.
Unlike the notation on Wikipedia, in program analysis we mostly use the following notation for the Join and Meet operators: - Join: ⊔ - Meet: ⊓
This notational convention makes it easier to notate lattice computations and logical formulae together.
In practice, data flow analysis only requires a "Join-Semilattices (Wikipedia)", though we do not make a strong distinction in the course.