* The converse of universality/pullback-stability
@ 2009-12-08 10:33 Tobias Heindel
0 siblings, 0 replies; only message in thread
From: Tobias Heindel @ 2009-12-08 10:33 UTC (permalink / raw)
To: categories
I have a short question concerning terminology related to extensive
categories. In the latter, coproducts enjoy the following property.
U ----> Z <---- V
| | |
| | |
v v v
A ---> A+B <--- B
/--------------------------------------------\
| In a double square diagram as illustrated, |
| the top row is a coproduct diagram |
| if and only if both squares are pullbacks. |
\--------------------------------------------/
The "if"-part of this condition is known as universality or
pullback-stability of co-products; it also can be formulated for
arbitrary colimits. What about the "only if" direction? Is there a
name for it in the case of arbitrary colimits?
Tobias Heindel
[For admin and other information see: http://www.mta.ca/~cat-dist/ ]
^ permalink raw reply [flat|nested] only message in thread
only message in thread, other threads:[~2009-12-08 10:33 UTC | newest]
Thread overview: (only message) (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2009-12-08 10:33 The converse of universality/pullback-stability Tobias Heindel
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).