TITLE: Library of posets in GAP?
QUESTION [6 upvotes]: Is there a way to obtain in GAP the Hasse diagrams of famous posets like the partition lattice or the divisor lattice of an integer? If they are not saved, is there a way to get them somehow else, like with using SAGE?
If not, is there a trick to obtain the Hasse diagram easily without programming everything from the start?
Are small posets or lattice saved in GAP? Like the ones with at most 7 points.

REPLY [2 votes]: It does, it's mentioned in Macaulay2's docs here

The GAP package Simplicial Homology, available at http://www.eecis.udel.edu/~dumas/Homology/, provides methods for using posets within GAP. According to the documentation, posets are stored in GAP in the following manor: The ground set is the set of integers 1..n+1 and the relations are stored in a list of length n, where the ith entry is the set of vertices which cover i in the poset. In particular, 1 should be the unique minimal element and n+1 should be the unique maximal element.

The link is now dead, and seems to be https://ljk.imag.fr/membres/Jean-Guillaume.Dumas/Homology/ instead now. You can find the old link on the Wayback Machine.
Note that this is not the simpcomp package.
I'm looking into the same problem and didn't know about the heights parameter in Sage, I'll probably use that instead but leaving this note in case it helps.
Specifically, I was trying to see if it was simple to make an integer partition lattice like it is in Sage, but it doesn't seem to be.