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From: Thomas Streicher <streicher@mathematik.tu-darmstadt.de>
To: Steve Vickers <s.j.vickers@cs.bham.ac.uk>
Cc: categories@mta.ca
Subject: Re: Fibred 2-category of Grothendieck toposes?
Date: Sun, 4 Dec 2016 13:00:48 +0100	[thread overview]
Message-ID: <E1cE3oa-0004Pl-1Q@mlist.mta.ca> (raw)
In-Reply-To: <2C7348C8-AAE0-4F33-A2B2-A4E112740F25@cs.bham.ac.uk>

Steve,

we are speaking about different things. Pullbacks of bgm's along
arbitrary gm's are described sufficiently well [Joh77] and in the
Elephant.

But what I have commented on was how to appropriately captured change
of base when studying topose sover a base topos.

I am working on the "algebraic" side whereas you think on the
"geometric" side. Reindexing in terms of the algebraic view is given
by precomposition but reindexing in terms of the geometric view is
postcomposition.

What I want to say is that pullbacks in Top are very different from
the change of base for relative topos theory.

Thomas


[For admin and other information see: http://www.mta.ca/~cat-dist/ ]


  parent reply	other threads:[~2016-12-04 12:00 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-12-02 10:20 Steve Vickers
     [not found] ` <2C7348C8-AAE0-4F33-A2B2-A4E112740F25@cs.bham.ac.uk>
2016-12-04 12:00   ` Thomas Streicher [this message]
     [not found] ` <98602071-6A60-42DF-BFC7-2C4E2745F980@cs.bham.ac.uk>
2016-12-05 10:26   ` Thomas Streicher
     [not found] <8135_1480682187_58416ACB_8135_508_1_E1cCn2y-0006W1-1X@mlist.mta.ca>
2016-12-02 13:30 ` Marta Bunge
2017-01-17 11:27 Steve Vickers

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