Sorry for this

[David Wilson]

I found out today that my wife has been hiding a foreclosure notice from me 
for a couple months.

Hope your days were better than mine.

Don't miss me if I drop out of sight for a while.





ma> From seqfan-owner at ext.jussieu.fr  Tue Feb 12 06:36:41 2008
ma> Date: Mon, 11 Feb 2008 21:36:01 -0800
ma> From: "Max Alekseyev" <maxale at gmail.com>
ma> To: SeqFan <seqfan at ext.jussieu.fr>
ma> Subject: Enumerating alcohols and other classes of chemical molecules
ma> 
ma> SeqFans,
ma> 
ma> I've just found a page
ma> http://algo.inria.fr/libraries/autocomb/Polya-html/Polya.html
ma> where a number of sequences related to enumeration of classes of
ma> chemical molecules are derived and references to the EIS book are
ma> given.
ma> But one of the sequences is described as
ma> 
ma> "This series does not appear in the book by N. J. A. Sloane and S.
ma> Plouffe [ The Encyclopedia of Integer Sequences , (1995), Academic
ma> Press]"
ma> 
ma> I've checked a few first terms in OEIS, and it is still not there.
ma> Could somebody with chemical background submit this sequence to OEIS
ma> with an appropriate description (a reference to this page and a maple
ma> code from there will be also useful)?
ma> 
ma> Also, it makes sense to find the other mentioned sequences (that are
ma> present in OEIS) and give a reference to this page in OEIS entries.
ma> 
ma> Thanks,
ma> Max

The problem starts when the author says that these chemical substances
are equivalent to rooted trees. I just cannot see why the simple
example of CH3-CH2-CH3 ought be called rooted on any of the three
carbons (unless you are able to stick it onto a specific solid surface,
which is an entirely different thing). So discussion and enumeration
of some forms of colored rooted trees is fine, but we must be able
to eliminate the structural duplicates that show up in the rooted versions
to end up with some standard gas-phase chemistry (which is different to
the sub-Kelvin surface chemistry). I guess this business
becomes fuzzy very quickly; we have to worry about definitions like
"di-ethyl-ester-full" , "not di-ethyl-ester-free" and the like. Enumerations
related to the real chemical structures would probably not be anymore similar
to the sequences found in the web page. A mine-field for anyone with some reputation
to loose as a mathematician or a chemist.

Richard