The Coq mailing list

[Maxime Dénès <mail AT maximedenes.fr>]

The anti-extensionality bug is indeed related to termination. More 
precisely, it is the subterm relation used by the guard checker which is 
not defined quite the right way on dependent pattern matching.

It is not too hard to fix (we have a patch), but doing so without ruling 
out any interesting legitimate example (dealing with recursion on 
dependently typed data structures) is more challenging.

I am also curious as to whether Agda is impacted. Let's try it :)

Maxime.

On 01/06/2014 12:59 PM, Altenkirch Thorsten wrote:
> Which bug was this?
>
> I only saw the one which allowed you to prove anti-extensionality? But
> this wasn't related to termination, or?
>
> Thorsten
>
> On 06/01/2014 16:54, "Cody Roux" 
> <cody.roux AT andrew.cmu.edu>
>  wrote:
>
> > Nice summary!
> >
> >
> > On 01/06/2014 08:49 AM, Altenkirch Thorsten wrote:
> > > Agda enforces termination via a termination checker which is more
> > > flexible but I think less principled than Coq's approach.
> >      That's a bit scary given that there was an inconsistency found in
> > the Coq termination checker just a couple of weeks ago :)
> >
> >      BTW, has anyone tried reproducing the bug in Agda?
> >
> >
> > Cody
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