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Re: [Coq-Club] Simplest example of impredicative Prop?

From: Arnaud Spiwack <aspiwack AT lix.polytechnique.fr>
To: "Benjamin C. Pierce" <bcpierce AT cis.upenn.edu>
Cc: coq-club AT inria.fr
Subject: Re: [Coq-Club] Simplest example of impredicative Prop?
Date: Fri, 27 Jul 2012 10:41:27 +0200

I don't know if we want Prop to be impredicative. And I don't know if my example is simple either. But I don't know any proof that surjectivity is equivalent to being epi in the category of setoids that doesn't use impredicativity.

Arnaud

On 25 July 2012 16:23, Benjamin C. Pierce <bcpierce AT cis.upenn.edu> wrote:

What is the most elementary example showing why we want Prop to be impredicative?

Thanks!

- Benjamin

[Coq-Club] Simplest example of impredicative Prop?, Benjamin C. Pierce, 07/25/2012
- Re: [Coq-Club] Simplest example of impredicative Prop?, Adam Chlipala, 07/25/2012
- Re: [Coq-Club] Simplest example of impredicative Prop?, gallais @ ensl.org, 07/25/2012
- Re: [Coq-Club] Simplest example of impredicative Prop?, Chung-Kil Hur, 07/25/2012
- Re: [Coq-Club] Simplest example of impredicative Prop?, Arnaud Spiwack, 07/27/2012
  - Re: [Coq-Club] Simplest example of impredicative Prop?, Bas Spitters, 07/30/2012
    - Re: [Coq-Club] Simplest example of impredicative Prop?, Arnaud Spiwack, 07/31/2012
      - Re: [Coq-Club] Simplest example of impredicative Prop?, Benjamin C. Pierce, 07/31/2012
        
        Re: [Coq-Club] Simplest example of impredicative Prop?, Arnaud Spiwack, 07/31/2012