From: claudio pisani <pisclau@yahoo.it>
To: categories@mta.ca
Subject: question on terminology
Date: Fri, 24 Aug 2012 20:03:59 +0100 (BST) [thread overview]
Message-ID: <E1T53tk-0004zl-Tw@mlist.mta.ca> (raw)
Dear categorists,
Is there a standard name for those presheaves X on a category C such that Xf is a bijection for any f in C?
I have sometimes called them "biactions" since any such X (considered as, say, a left action of C) is paired with the obvious presheaf X' on C^op (a right action of C): X'f = (Xf)^-1.
Of course, they correspond, as categories over C, to discrete bifibrations.
I also know that the separable or decidable presheaves are those for which every Xf is injective.
Claudio
[For admin and other information see: http://www.mta.ca/~cat-dist/ ]
next reply other threads:[~2012-08-24 19:03 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-08-24 19:03 claudio pisani [this message]
-- strict thread matches above, loose matches on Subject: below --
2012-08-26 4:59 Fred E.J. Linton
[not found] <977qHyDIk8016S03.1345865710@web03.cms.usa.net>
2012-08-25 13:58 ` claudio pisani
2012-08-27 22:03 ` David Roberts
2012-08-25 3:35 Fred E.J. Linton
2010-02-04 17:39 Question " lamarche
2010-02-06 0:12 ` Toby Bartels
2010-02-06 0:21 ` Steve Lack
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