From: Richard Garner <richard.garner@mq.edu.au>
To: Categories list <categories@mta.ca>
Subject: Tensor product of left exact morphisms
Date: Thu, 26 Mar 2015 12:27:32 +1100 [thread overview]
Message-ID: <E1Yb6og-0000q0-EU@mlist.mta.ca> (raw)
Dear categorists,
If G is a group, then [G,Set] is the classifying topos for right
G-torsors.
What about the classifying topos for possibly non-transitive torsors?
I'm not very adept at these calculations, but if I construct it as a
subtopos of the classifying topos for G^op-sets, it appears to come out
as [X,Set] where X is the category of finitely presentable, free,
non-empty G^op-sets.
Similarly, if G is a groupoid, the corresponding classifying topos
appears to be [X,Set], where X is the full subcategory of [G^op, Set] on
those finite coproducts of representables which have global support.
Is this correct?
Richard
[For admin and other information see: http://www.mta.ca/~cat-dist/ ]
next reply other threads:[~2015-03-26 1:27 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-03-26 1:27 Richard Garner [this message]
2015-03-26 15:00 ` Joyal, André
[not found] ` <8C57894C7413F04A98DDF5629FEC90B1137B097E@Pli.gst.uqam.ca>
2015-03-26 23:08 ` Richard Garner
2015-03-27 13:08 ` henry
2015-03-28 8:40 ` Richard Garner
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