From: Robin Cockett <robin@ucalgary.ca>
To: "categories@mta.ca" <categories@mta.ca>, Dana Scott <scott@cs.cmu.edu>
Subject: Re: An elementary question
Date: Mon, 14 Aug 2017 18:51:22 +0000 [thread overview]
Message-ID: <E1dhfjY-0001hJ-DR@mlist.mta.ca> (raw)
In-Reply-To: <E1dh2U9-0000c9-3y@mlist.mta.ca>
A great question ... and I do not have an answer for it. However, regarding P (<) Q as a (posetal) module between the posets it does have the striking property that it is the final module!
-robin
________________________________
From: Dana Scott <scott@cs.cmu.edu>
Sent: Sunday, August 13, 2017 1:55:11 PM
To: categories@mta.ca
Subject: categories: An elementary question
The category of posets (= partially ordered sets) and monotone
maps is often used as an easy example -- different from the category
of sets -- that has products, coproducts, and is cartesian closed
but not a topos.
Let P and Q be two posets. Define (P (<) Q) as the modified
coproduct where all the elements of P are made less than all the
elements of Q. QUESTION. Does (P (<) Q) have a nice categorical
definition as a functor in the category of posets?
[For admin and other information see: http://www.mta.ca/~cat-dist/ ]
next prev parent reply other threads:[~2017-08-14 18:51 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-08-13 19:55 Dana Scott
2017-08-14 0:15 ` alex
2017-08-14 4:42 ` Patrik Eklund
2017-08-14 18:43 ` Mike Stay
2017-08-15 5:57 ` Vaughan Pratt
[not found] ` <fa2a57444ecc56bfc61165f2263d42e5@cs.umu.se>
2017-08-15 14:21 ` Mike Stay
2017-08-14 8:00 ` Paul Blain Levy
2017-08-14 18:51 ` Robin Cockett [this message]
[not found] ` <CAKQgqTb4f=+Y=SuCu26AKg3Wd02friY_6z9FhukXiSnoapLZRQ@mail.gmail.com>
2017-08-15 4:50 ` Patrik Eklund
2017-08-15 21:49 ` Joachim Kock
2017-08-17 2:02 ` Branko Nikolić
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