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Re: [Coq-Club] Proof irrelevance for equalities - is there a trick without axioms?


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  • From: Jonathan Leivent <jonikelee AT gmail.com>
  • To: coq-club AT inria.fr
  • Subject: Re: [Coq-Club] Proof irrelevance for equalities - is there a trick without axioms?
  • Date: Wed, 17 Aug 2016 19:28:39 -0400
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On 08/17/2016 07:24 PM, Jason Gross wrote:
Oooh, nice!

Something strange seems to be going on here, though. Why does this not
replace H1 with eq_refl?

Goal forall (T : Type) (feq : Eq=Eq->T) (H1 : Eq=Eq), feq eq_refl = feq H1.
intros.
revert dependent H1.
refine (fun H1 => match H1 with eq_refl => _ end).

But, this does work (replacing the hole in the refine with eq_refl):

Goal forall (T : Type) (feq : Eq=Eq->T) (H1 : Eq=Eq), feq eq_refl = feq H1.
intros.
revert dependent H1.
refine (fun H1 => match H1 with eq_refl => eq_refl end).
Qed.

That's another strange behavior of return clause inference - sometimes it needs help like this, and sometimes not.

-- Jonathan


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