1 (**************************************************************************)
4 (* ||A|| A project by Andrea Asperti *)
6 (* ||I|| Developers: *)
7 (* ||T|| The HELM team. *)
8 (* ||A|| http://helm.cs.unibo.it *)
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11 (* v GNU General Public License Version 2 *)
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15 set "baseuri" "cic:/matita/logic/iff".
17 include "../../library/logic/connectives.ma".
19 definition Iff : Prop \to Prop \to Prop \def
20 \lambda A,B. (A \to B) \land (B \to A).
22 (*CSC: the URI must disappear: there is a bug now *)
23 interpretation "logical iff" 'iff x y = (cic:/matita/logic/iff/Iff.con x y).
25 notation > "hvbox(a break \liff b)"
26 left associative with precedence 25
29 notation < "hvbox(a break \leftrightarrow b)"
30 left associative with precedence 25