Subject: Re: 2 questions
Date: Wed, 28 Aug 2002 11:55:58 -0400
From: Murray Gerstenhaber <mgersten@math.upenn.edu>
To: Don Davis <dmd1@lehigh.edu>

Reply to "stupid queston" (which is not so stupid!):
Please see Murray Gerstenhaber and Samuel D. Schack, "The cohomology of
presheaves of algebras. I: Presheaves over a partially orderd set",
Transactions Amer. Math. Soc. 310 (1988) 135-165, and (if you have
access to it) (same authors) "Algebraic cohomology and deformation
theory" inbook "Deformation Theory of Algebras and Structures and
Deformations", Michiel Hazewinkel and Murray Gerstenhaber, eds. Kluwer,
1988, pp 11-264. (See particularly sections 17 to 23.) Unfortunately the
book is very expensive but there used to be some arrangement to get it
cheaply for use as a text. (If you can't get it, please let me know;
maybe I can get some pages copied.)
Murray Gerstenhaber

Don Davis wrote:
>
> Two postings, both questions..........DMD
> ______________________________________________
>
> Subject: cup product and Yoneda product
> Date: Tue, 27 Aug 2002 14:59:00 -0400 (ART)
> From: Mariano Suarez-Alvarez <aldoc9@mate.dm.uba.ar>
>
> I guess this is folklore, but I could not find it; maybe some one on the
>
> list can provide a reference:
>
> Does the cup-product on the cohomology of a space X with values in a
> comm.
> ring R coincide with the Yoneda product on the self-extension algebra
> Ext(R,R) of the constant sheaf of rings R on X in the category of
> sheaves
> of R-Modules?
>
> Thanks,
>
> -- m
>
> Mariano Suarez-Alvarez
> Departamento de Matemática
> Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires
> Ciudad Universitaria, Pabellón I. Buenos Aires (1428). Argentina.
> http://mate.dm.uba.ar/~aldoc9
> _______________________________________________________
>
>    Subject: Fwd: stupid question
> Date: Wed, 28 Aug 2002 09:33:14 +0100
> From: Dr Andrew Baker <a.baker@maths.gla.ac.uk>
>
> ----- Forwarded message from Caitlin Horn <caitlin_horn@hotmail.com>
> -----
>     Date: Tue, 27 Aug 2002 14:00:00 +0000
>     From: Caitlin Horn <caitlin_horn@hotmail.com>
> Reply-To: Caitlin Horn <caitlin_horn@hotmail.com>
>  Subject: stupid question
>       To: a.baker@maths.gla.ac.uk
>
> Hi there,
>
> My name is Caitlin Horn and I'm currently doing a PhD in inorganic
> chemistry
> at the uni of Nottingham.  I've made a compound which contains lots of
> iodine, and the iodine atoms line up to form a kind of helix, which is
> in
> cross section like a figure of 8 (well, more like a bow-tie, but
> whatever).
> See the attached jpeg for an idea of what I mean.  My question is: does
> this
> type of helix have a special name? I'm writing a paper on it and
> "figure-of-8-helix" doesn't exactly roll off the tongue (or the
> fingers!).
> I'd be very grateful for any information you can provide...
>
> Thanks loads,
> Caitlin
>
> --
> Dr Andrew Baker (Reader in Mathematics)
> Department of Mathematics
> University of Glasgow
> Glasgow G12 8QW
>
>   ------------------------------------------------------------------------
>  [Image]  [Image]