From: Peter Freyd <pjf@saul.cis.upenn.edu>
To: categories@mta.ca
Subject: Re: Name for a concept
Date: Wed, 7 Dec 2005 08:36:12 -0500 (EST) [thread overview]
Message-ID: <200512071336.jB7DaCmS021736@saul.cis.upenn.edu> (raw)
Jean asks:
Is there a standard name for the squares where the canonical map
is monic , i.e. the pair of maps A --->B and A --->C is jointly
monic.
In the early 60s at the annual AMS meeting held at Denver, Eilenberg,
Mac Lane and I sat down to "settle" the terminology. ("Denver One" I
called it.) There were just two things we totally agreed on: "weak" is
the operator on definitions that removes uniqueness conditions and
"partial" the operator that removes existence conditions. So the
answer to Jean's question would be "partial pullback".
As for the other side -- when the pair of maps are jointly epic --
I've seen them called "near-pullbacks" in the theoretical computer
science community. Functors between regular categories that preserve
near-pullbacks are precisely those that preserve "weak tabulations"
of (n-ary) relations.
next reply other threads:[~2005-12-07 13:36 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-12-07 13:36 Peter Freyd [this message]
-- strict thread matches above, loose matches on Subject: below --
2005-12-08 11:26 name " Clemens.BERGER
2005-12-08 11:06 Clemens.BERGER
2005-12-06 10:12 Name " jean benabou
2005-12-07 0:58 ` Toby Bartels
2005-12-07 19:15 ` Eduardo Dubuc
2005-12-05 14:44 Marco Grandis
2005-12-01 1:48 Michael Barr
2005-12-02 11:19 ` Ronald Brown
2005-12-02 13:51 ` Marco Grandis
2005-12-05 16:16 ` Eduardo Dubuc
2005-12-07 11:04 ` Marco Grandis
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