From: "Mamuka Jibladze" <jib@rmi.acnet.ge>
To: "Peter Freyd" <pjf@saul.cis.upenn.edu>, <categories@mta.ca>
Subject: Re: dualities
Date: Sun, 30 Apr 2006 20:56:34 +0400 [thread overview]
Message-ID: <E1FacnK-0005I2-9F@mailserv.mta.ca> (raw)
> Next is Pontryagin's: the category of locally compact groups. The
> original Pontryagin duality easily generalizes: the category of
> locally compact modules over a given commutative ring is self-dual.
> (In the non-commutative case one also obtains a duality but not a
> self-duality -- unless, of course, the ring is self-dual.) A corollary
> is that the category of discrete left R-modules is dual to the
> category of compact right R-modules. (For 50 years I've been trying to
> turn this into an exercise in abelian categories. There's a nice
> reduction down to the proposition that R/Z is a cogenerator for the
> category of compact abelian groups, but that fact seems to require
> some non-trivial functional analysis.)
This reminded me of a long-standing torture: does anybody know an elementary
proof at least of the particular case when the base ring - thus the dualizer
too - has only two elements? (Demanded by Guram Bezhanishvili; I agreed to
try thinking on this one as it seemed somehow close to Boolean algebras,
but...)
> Then, of course there's my present favorite: the category of finitely
> presented group-valued functors from the category of finitely
> presented modules over a commutative ring.
Yes, yes?
next reply other threads:[~2006-04-30 16:56 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-04-30 16:56 Mamuka Jibladze [this message]
-- strict thread matches above, loose matches on Subject: below --
2006-05-04 6:39 dualities Vaughan Pratt
2006-05-03 16:40 dualities Vaughan Pratt
2006-05-02 22:05 dualities John Baez
2006-05-02 5:39 dualities Vaughan Pratt
2006-05-01 20:02 dualities Ronnie Brown
2006-05-01 19:06 dualities Michael Barr
2006-05-01 11:46 dualities K C H Mackenzie
2006-04-30 19:28 dualities Vaughan Pratt
2006-04-29 14:14 dualities Peter Freyd
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