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 *)
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15 include "ground/lib/subset_ext_inclusion.ma".
16 include "ground/lib/subset_equivalence.ma".
18 (* EXTENSIONS FOR SUBSETS ***************************************************)
20 (* Constructions with subset_equivalence ************************************)
22 lemma subset_equivalence_ext_f1_bi (A1) (A0) (f) (u1) (v1):
23 u1 ⇔ v1 → subset_ext_f1 A1 A0 f u1 ⇔ subset_ext_f1 A1 A0 f v1.
24 #A1 #A0 #f #u1 #v1 * #Huv1 #Hvu1
25 /3 width=3 by subset_inclusion_ext_f1_bi, conj/