[seqfan] Re: Giving a mathematical definition to A280001

[Natan Consigli]

Ok, I'll propose them for review as soon as there are ready

On Sun, Feb 5, 2017 at 9:17 PM, Neil Sloane <njasloane at gmail.com> wrote:

>  Since A280001 is being discussed on this list, it is best if we have
> a concrete version to look at, so I am going to approve the current
> version. Natan, if there are errors that you know about in this
> version, please correct them.
> Best regards
> Neil
>
> Neil J. A. Sloane, President, OEIS Foundation.
> 11 South Adelaide Avenue, Highland Park, NJ 08904, USA.
> Also Visiting Scientist, Math. Dept., Rutgers University, Piscataway, NJ.
> Phone: 732 828 6098; home page: http://NeilSloane.com
> Email: njasloane at gmail.com
>
>
>
> On Fri, Feb 3, 2017 at 9:24 AM, Natan Consigli
> <origami.experience at gmail.com> wrote:
> > The drawings are three dimensional. In the PDF attached to A280001 there
> > are molecules with a dashed and wedge bonds which in chemistry generally
> > mean that they point inwards and outwards respectively.
> > I'll also attach the link as required by the moderator:
> > https://oeis.org/draft/A280001/a280001.pdf
> >
> > On Thu, Feb 2, 2017 at 11:26 AM, Natan Consigli <
> > origami.experience at gmail.com> wrote:
> >
> >> The drawings are three dimensional. In the attached PDF there are
> >> molecules with a dashed and wedge bonds which in chemistry generally
> mean
> >> that they point inwards and outwards respectively.
> >>
> >>
> >> On Thu, Feb 2, 2017 at 7:24 AM, Charles Greathouse <
> >> charles.greathouse at case.edu> wrote:
> >>
> >>> This is a worthwhile project! But I'm not sure that I understand your
> >>> question. Being a planar graph is already a standard graph-theoretic
> >>> primitive, or is this used in some special way in chemistry?
> >>>
> >>>
> >>>
> >>> Charles Greathouse
> >>> Case Western Reserve University
> >>>
> >>> On Wed, Feb 1, 2017 at 12:04 AM, Natan Consigli <
> >>> origami.experience at gmail.com> wrote:
> >>>
> >>> > Also, I have to mention that the graphs are three-dimensional for
> >>> > stereoisomer distinction
> >>> >
> >>> > On Wed, Feb 1, 2017 at 5:57 AM, Natan Consigli <
> >>> > origami.experience at gmail.com
> >>> > > wrote:
> >>> >
> >>> > > Dear Seqfans,
> >>> > >
> >>> > > I am trying to define A280001 mathematically with graph theory. To
> let
> >>> > the sequence be less "obscure" I have to define what does chemical
> >>> > aromaticity mean.
> >>> > >
> >>> > > Here is what I did so far.
> >>> > >
> >>> > > As far as being a hydrocarbon I am looking for a connected
> multigraph
> >>> > (non looped for some authors) where each node has degree less than
> five
> >>> > (octet rule).
> >>> > >
> >>> > > For the condition of being aromatic I need a connected subset of
> nodes
> >>> > that satisfies Huckel's rule. This means that such subset must have
> the
> >>> > following:
> >>> > >
> >>> > > 1) an alternating connection 1-edge/2-edge vertices (conjugated pi
> >>> > system);
> >>> > >
> >>> > > 2) the number of 2-edge connections must be odd (4n+2 pi
> electrons);
> >>> > >
> >>> > > 3) the subset of nodes must represent a chemically planar portion
> of
> >>> the
> >>> > molecule.
> >>> > >
> >>> > > I find stating rule 3 in a mathematical way very hard to do. If
> >>> anybody
> >>> > has ideas I would appreciate your help.
> >>> > >
> >>> > > Natan Consigli
> >>> > >
> >>> > >
> >>> >
> >>> > --
> >>> > Seqfan Mailing list - http://list.seqfan.eu/
> >>> >
> >>>
> >>> --
> >>> Seqfan Mailing list - http://list.seqfan.eu/
> >>>
> >>
> >>
> >
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