[isabelle-dev] Regression in the sublocale command

[Florian Haftmann]

Hi Clemens,

thanks for investigating this.

Am 12.02.2015 um 22:19 schrieb Clemens Ballarin:
> Hi Florian,
> 
> I'm investigating a regression which prevents identifying certain equivalent locales through circular sublocale declarations:
> 
>   sublocale loc1 < x: loc2 A c (* sigma_1 *)
>     where "x.b == B" and "x.d == e" (* tau_1 *)
>   sorry
> 
>   sublocale loc2 < x: loc1 A b (* sigma_2 *)
>     where "x.c == C" and "x.e == d" (* tau_2 *)
>   sorry (* loops from changeset 8fab871a2a6f *)
> 
> The last "sorry" loops, which is unfortunate, because it forces certain workarounds on my current project.
> In a fairly lengthy debug session I figured out that it is the simplifier that loops. 
> This is an indication that the morphisms tau_1 and tau_2 are applied simultaneously, which they should not.
> In any case, the behaviour appears to have been introduced quite a
while ago in 8fab871a2a6f, which is in the first batch of your changes
to the locale interpretation commands.

I guess you found out using bisection.  But I read some incertainty in
your words »appears to have been introduced«.  Is the changeset
8fab871a2a6f a reliable entrance point or a first approximation?

I will have a closer look at this.

Cheers,
	Florian

-- 

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