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RE: [Coq-Club] forall implication


Chronological Thread 
  • From: "Soegtrop, Michael" <michael.soegtrop AT intel.com>
  • To: "coq-club AT inria.fr" <coq-club AT inria.fr>
  • Subject: RE: [Coq-Club] forall implication
  • Date: Mon, 27 Apr 2015 15:40:06 +0000
  • Accept-language: de-DE, en-US

Dear Richard,

below is a proof, that this is actually wrong. It gives a counter example,
which shows where the problem is.

Best regards,

Michael

Lemma ThisIsWrong:
(forall (T:Set) (P:T->Prop), forall (x:T), P x -> (forall y, P y))
-> False.
Proof.
intros H.
specialize (H bool).
specialize (H (fun b => b=true)).
specialize (H true).
simpl in H.
specialize (H eq_refl).
specialize (H false).
inversion H.
Qed.

Lemma ThisIsRight:
forall (T:Set) (P:T->Prop), (forall (x:T), P x) -> (forall y, P y).
Proof.
intros T P H.
assumption.
Qed.




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