From: Andrej Bauer <Andrej.Bauer@andrej.com>
To: categories@mta.ca
Subject: Re: Cauchy completeness of Cauchy reals
Date: 28 Jan 2003 10:44:41 +0100 [thread overview]
Message-ID: <vkafzrdobg6.fsf@laurie.fmf.uni-lj.si> (raw)
In-Reply-To: Alex Simpson's message of "Tue, 28 Jan 2003 01:50:18 +0000 (GMT)"
Alex Simpson <als@inf.ed.ac.uk> writes:
>
> > The map e : 2^N --> [0,1] defined by
> >
> > e x = x_0/2 + x_1/4 + x_2/8 + ...
> >
> > is epi in the effective topos, but it is not regular epi.
>
> This is clearly wrong. Every epi is regular, in a topos.
>
> My original statement was correct. In the effective topos,
> the map from binary representations to Cauchy (= Dedekind)
> reals is not epi.
I stand corrected. I am confusing the effective topos with assemblies
(or modest sets) over the first Kleene algebra.
Andrej
next reply other threads:[~2003-01-28 9:44 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2003-01-28 9:44 Andrej Bauer [this message]
-- strict thread matches above, loose matches on Subject: below --
2003-01-28 20:51 Dusko Pavlovic
2003-01-29 2:00 ` Toby Bartels
2003-01-29 8:35 ` Alex Simpson
2003-02-04 9:15 ` Dusko Pavlovic
2003-02-05 20:56 ` Toby Bartels
2003-01-27 17:41 Andrej Bauer
2003-01-28 1:50 ` Alex Simpson
2003-01-16 23:05 Generalization of Browder's F.P. Theorem? Michael Barr
2003-01-21 18:11 ` Andrej Bauer
2003-01-22 10:13 ` Cauchy completeness of Cauchy reals Martin Escardo
2003-01-22 23:33 ` Dusko Pavlovic
2003-01-24 8:51 ` Martin Escardo
2003-01-25 2:21 ` Dusko Pavlovic
2003-01-25 16:24 ` Prof. Peter Johnstone
2003-01-27 3:57 ` Alex Simpson
2003-01-23 6:29 ` Vaughan Pratt
2003-02-04 0:47 ` Vaughan Pratt
2003-02-05 16:06 ` Prof. Peter Johnstone
2003-01-23 9:50 ` Mamuka Jibladze
2003-01-24 1:34 ` Ross Street
2003-01-24 16:56 ` Dusko Pavlovic
2003-01-24 19:48 ` Dusko Pavlovic
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