[seqfan] Re: Giving a mathematical definition to A280001

Natan Consigli origami.experience at gmail.com
Fri Feb 3 15:24:15 CET 2017


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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