[seqfan] Re: When are stereoisomers counted in A000628?

Natan Consigli origami.experience at gmail.com
Thu Feb 9 16:29:44 CET 2017


I think what you just said is precisely what the comments really mean. A_4
gives the rotations of the molecule and S_4 includes reflections which is
exactly the group that can orbit a R stereoisomer into an S one.
An other thing is that I found other sequences containing the comment in
A000628. Should I fix them or is it better that the editors handle this?

On Thu, Feb 9, 2017 at 12:55 PM, Richard J. Mathar <mathar at mpia-hd.mpg.de>
wrote:

> With reference to http://list.seqfan.eu/pipermail/seqfan/2017-
> February/017255.html:
>
> The phrase is not useful in both cases, because it is not important with
> which
> group you act on the molecule (you can act with any geometric group on any
> molecule if you wish) but whether that molecule is symmetric (an
> "eigenvector")
> or non-symmetric upon action of the symmetry group.
>
> What the comment means to say is (?) that in A000628 molecules are counted
> if
> they are not symmetric under actions of S_4, whereas they are counted in
> A000602 if they are not symmetric under actions of A_4.
>
>
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>


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