From: Richard Garner <rhgg2@hermes.cam.ac.uk>
To: categories@mta.ca
Subject: Cartesian closed without products
Date: Mon, 7 Jan 2008 11:08:55 +0000 (GMT) [thread overview]
Message-ID: <E1JBxJG-0001VE-Qa@mailserv.mta.ca> (raw)
Dear categorists,
A small category C has finite products just when the
representables in [C^op, Set] are closed under finite
products. It is cartesian closed just when the representables
are closed under finite products and internal hom.
It seems natural, therefore, to consider a notion of
"cartesian closedness without finite products": categories in
which the representables are closed in [C^op, Set] under
internal hom but not necessarily under finite products. This
amounts to giving, for each pair of objects X and Y, an
object [X, Y] together with a universal natural
transformation C(-, [X, Y]) x C(-, X) -> C(-, Y). Such
categories will be closed in the sense of Eilenberg-Kelly
without necessarily being monoidal: let us call them
"universally closed" for now.
Obviously, any cartesian closed category is universally
closed; and categorical proof theory gives us a class of
non-degenerate examples built from the syntax of (classical)
sequent calculi with implication but no product.
The question now arises as to whether there are any
non-syntactic examples of universally closed categories which
are not cartesian closed. The most likely place seems to me
to be domain theory, but I have been unable to track anything
down. Does anyone have any pointers?
Thanks,
Richard.
next reply other threads:[~2008-01-07 11:08 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-01-07 11:08 Richard Garner [this message]
2008-01-07 14:09 Richard Garner
2008-01-07 21:35 Toby Bartels
2008-01-08 21:29 Ronnie
2008-01-09 1:36 Peter Selinger
2008-01-09 2:29 Toby Bartels
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