Hasse diagram layout

[alexpghayes]

http://mathworld.wolfram.com/HasseDiagram.html

In particular this would pave the way for utilities to turn lme* style model objects into Hasse diagrams.

[thomasp85]

Do you have any pointers to a good layout algorithm for this... it appears that optimal drawing of Hasse diagrams is a pretty tough problem... (btm, the underlying structure is just a DAG which can be shown with a sugiyama layout)

[alexpghayes]

Sadly not. However, my goal here would be to produce diagrams in style of http://users.stat.umn.edu/~gary/book/fcdae.pdf. Chapter 11 in particular describes how to make these diagrams.