From: categories <cat-dist@mta.ca>
To: categories <categories@mta.ca>
Subject: Terminology for Kan extensions
Date: Wed, 28 Jan 1998 10:22:45 -0400 (AST) [thread overview]
Message-ID: <Pine.OSF.3.90.980128102231.845A-100000@mailserv.mta.ca> (raw)
Date: Wed, 28 Jan 1998 10:25:34 +0000 (GMT)
From: Ronnie Brown <r.brown@bangor.ac.uk>
There seems some confusion as to whether Left Kan extensions are right
Kan extensions and conversely, and it seems different authors use
different conventions.
What do people think of using a terminology analogous to limits and
colimits, i.e. Kan extensions and Kan coextensions? In particular, what
Carmody and Walters call left Kan extensions would here be Kan
coextensions, which can be constructed as coends (as in Mac Lane, CFTWM).
This point has come from Anne Heyworth, where left Kan extensions use
right rewriting, if you write composition in a category in the algebraic
rather than functional way.
Any other ideas?
Ronnie
Prof R. Brown, School of Mathematics,
University of Wales, Bangor
Dean St., Bangor, Gwynedd LL57 1UT, United Kingdom
Tel. direct:+44 1248 382474|office: 382475
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reply other threads:[~1998-01-28 14:22 UTC|newest]
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