#19191: LatticePoset: add is_planar()
-------------------------------------+-------------------------------------
Reporter: jmantysalo | Owner:
Type: enhancement | Status: needs_review
Priority: major | Milestone: sage-6.9
Component: combinatorics | Resolution:
Keywords: | Merged in:
Authors: Jori Mäntysalo | Reviewers:
Report Upstream: N/A | Work issues:
Branch: | Commit:
u/jmantysalo/latticeposet__add_is_planar__|
c669ecbf2476518175f0719ba25e76cdc05f1521
Dependencies: | Stopgaps:
-------------------------------------+-------------------------------------
Comment (by ncohen):
Jori,
Up to now, in all papers that I have seen, a Poset is defined to be planar
when its hasse diagram is planar. Have you even found one paper that
defines it differently?
If there is to be a `Lattice.is_planar` or a `Poset.is_planar`, I expect
it to be `self._hasse_diagram.is_planar()`, and nothing else. Even the
paper that mentions this additional edge between 0 and n-1 uses *this*
definition (without the additional edge) and apparently proves that you
can add this edge without changing the property.
The least I can say is that I *know* that some people would be entitled to
believe that `Lattice.is_planar` does not add any edge, even without
reading the documentation (did you ever read the documentation of
`is_even` ?). And those must not be mislead.
If you want to implement another definition, it will have to be under
another name.
Nathann
--
Ticket URL: <http://trac.sagemath.org/ticket/19191#comment:17>
Sage <http://www.sagemath.org>
Sage: Creating a Viable Open Source Alternative to Magma, Maple, Mathematica,
and MATLAB
--
You received this message because you are subscribed to the Google Groups
"sage-trac" group.
To unsubscribe from this group and stop receiving emails from it, send an email
to [email protected].
To post to this group, send email to [email protected].
Visit this group at http://groups.google.com/group/sage-trac.
For more options, visit https://groups.google.com/d/optout.
