A set $P \subseteq \mathcal{P}(X)$ is a partition of $X$ if and only if all of the following conditions hold:
- $\emptyset \notin P$
- For all $x,y \in P$, if $x \neq y$ then $x \cap y = \emptyset$.
- $\bigcup P = X$
I have read many times that the partitions of a set form a lattice, but never really considered the idea in great detail. Where can I learn the major results about such lattices? An article recommendation would be nice.
I'm also interested in the generalization where condition 3 is disregarded.
G. Birkhoff, Lattice Theory. Providence, Rhode Island, 1967,
Chapt.4, sec.9.