LaTeX.org

That works of course, but things aren't always that regular, for instance the lattice of partitions of a set of four elements ordered by inclusion as in http://en.wikipedia.org/wiki/Hasse_diagram. I was wondering whether it's possible to align nodes in a more general way instead of having them fixed ...

Yes, but in that case you're limited to the lay-out of the matrix. Each row should get aligned according to the number of nodes present in it, not by some smallest common multiple of the number of elements.

In Galois theory (and many other parts of mathematics) one often finds Galois correspondence. This can be represented in a Hasse diagram. Now I'm looking for a way to draw these Hasse diagrams. An example can be found in the attachment, it's from http://www.galois-theorie.de/. More examples of Hasse ...