1 (**************************************************************************)
4 (* ||A|| A project by Andrea Asperti *)
6 (* ||I|| Developers: *)
7 (* ||T|| The HELM team. *)
8 (* ||A|| http://helm.cs.unibo.it *)
10 (* \ / This file is distributed under the terms of the *)
11 (* v GNU General Public License Version 2 *)
13 (**************************************************************************)
14 include "logic/equality.ma".
22 ∀H : ∀x.g x a = g a x.
23 ∃y,z. f (g y b) y = f (g z a) a.
24 #U. #a. #b. #f. #g. #H.
25 napply (ex_intro ????);
26 ##[ ##2: napply (ex_intro ????);
27 ##[ ##2: nauto by H. ##| ##skip ##] ##| ##skip ##] nqed.
35 ∀H : ∀x.g x a = g a x.
36 ∃y,z. f y (g y b) = f a (g z a).
37 #U. #a. #b. #f. #g. #H.
38 napply (ex_intro ????);
39 ##[ ##2: napply (ex_intro ????);
40 ##[ ##2: nauto by H. ##| ##skip ##] ##| ##skip ##] nqed.
48 ∀H : ∀x.g x a = g a x.
49 ∃y,z. f (g z a) (g y b) = f (g y b) (g z a).
50 #U. #a. #b. #f. #g. #H.
51 napply (ex_intro ????);
52 ##[ ##2: napply (ex_intro ????);
53 ##[ ##2: nauto by H. ##| ##skip ##] ##| ##skip ##] nqed.