From: Tony Meman <tonymeman1@googlemail.com>
To: categories <categories@mta.ca>
Subject: Comma categories
Date: Thu, 24 Sep 2009 22:23:22 +0200 [thread overview]
Message-ID: <E1MqvuI-0005uu-ID@mailserv.mta.ca> (raw)
Dear category theorists,
I have two questions concerning comma categories.
If C is a category with a terminal object *, is the comma category (C,*)
consisting of arrows from C to * isomorphic to the category C itself? If
this is true, the same should apply to the dual case with an initial object.
The category sSet of simplicial sets is the category of functors from the
opposite delta category Delta^op to Set. The category of pointed simplicial
sets sSet* is defined as the comma category (delta0, sSet), where
delta0=hom(-,[0]). Is sSet* isomorphic to the category of functors from
([0],Delta)^op to Set?
Thank you in advance for any help.
Tony
[For admin and other information see: http://www.mta.ca/~cat-dist/ ]
next reply other threads:[~2009-09-24 20:23 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-09-24 20:23 Tony Meman [this message]
-- strict thread matches above, loose matches on Subject: below --
2009-09-24 22:37 Steve Lack
2007-11-08 1:32 Robert L Knighten
2007-11-08 0:05 Bill Lawvere
2007-11-05 12:21 claudio pisani
2007-11-02 16:12 wlawvere
2007-10-31 15:20 Uwe Egbert Wolter
1998-10-20 21:11 F W Lawvere
1998-10-20 0:26 Ross Street
1998-10-19 16:14 Manuel Bullejos
1998-10-19 17:19 ` Vaughan Pratt
1997-07-01 18:13 comma categories categories
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