From: Andrew Stacey <andrew.stacey@math.ntnu.no>
To: Michael Barr <barr@math.mcgill.ca>
Cc: Categories list <categories@mta.ca>
Subject: Re: Another question on Grothendieck
Date: Mon, 30 Aug 2010 20:04:43 +0200 [thread overview]
Message-ID: <E1Oqaj2-0004kH-9P@mlist.mta.ca> (raw)
In-Reply-To: <E1Oq7DH-0001gU-Pk@mlist.mta.ca>
On Mon, Aug 30, 2010 at 10:18:30AM -0400, Michael Barr wrote:
> Grothendieck introduces, on the top of p. 209 of the Tohoku paper, the
> notation U_{i_0..i_p} without explanation and uses it again over the next
> couple pages. Here {U_i} is an open cover of a space X and I have reason
> to believe that this stands for the intersection of U_{i_j}. Can anyone
> confirm this? Or give an alternate explanation?
>
> The context is that of a claim that (when A is a sheaf) and "every
> U_{i_0..i_p} is A-acyclic, then"... and that awfully like the definition of
> a simple cover.
I have absolutely no idea as to what Grothendieck meant, but the notation you
describe is quite common in (algebraic) topology and means what you "have
reason to believe" that it means.
Andrew
[For admin and other information see: http://www.mta.ca/~cat-dist/ ]
next prev parent reply other threads:[~2010-08-30 18:04 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-08-30 14:18 Michael Barr
2010-08-30 18:04 ` Andrew Stacey [this message]
[not found] ` <E1Or9Si-00031p-Iw@mlist.mta.ca>
2010-09-03 6:46 ` Vaughan Pratt
[not found] ` <4C819AD7.8090403@dm.uba.ar>
2010-09-04 7:04 ` Vaughan Pratt
[not found] ` <4C82A02D.7090703@dm.uba.ar>
2010-09-05 23:23 ` Vaughan Pratt
[not found] ` <E1Ort7T-00087z-SA@mlist.mta.ca>
2010-09-05 19:51 ` Steven Vickers
2010-09-06 17:53 ` Eduardo J. Dubuc
2010-08-31 5:50 ` John Baez
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