I'm trying to create a poset whose elements are frozen sets (they are certain chains of subsets of flats of a matroid), and I'm getting unexpected behavior. For example:
sage: elts = [frozenset({1, 2, 3}), frozenset({3, 4, 5}), frozenset({1, 3, 4})]
sage: rels = [frozenset({1,2,3}), frozenset({3,4,5})]
sage: Poset(elts, rels)
Finite poset containing 6 elements
The elements are:
frozenset({1, 2, 3})
2
frozenset({3, 4, 5})
3
4
5
Why does this happen?
