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(* 02110-1301 USA                                                     *)
(** In this file, we prove properties about hedges. These properties are in section 6.1 of the paper "On Bisimulations for the Spi-Calculus" by J. Borgström and U. Nestmann. However, we consider here an extended message language. *)
(** Author: Sébastien Briais (sebastien.briais@epfl.ch) *)
Unset Standard Proposition Elimination Names.
(** We assume to have a (countably infinite) set of names. *)
Hypothesis Nam : Set.
(** We define three operators for building messages. *)
Inductive op : Set :=
| Pub : op
| Priv : op
| Hash : op.

(** Equality of operators is decidable. *)
Lemma op_eq_dec : forall o1 o2 : op, {o1 = o2} + {o1 <> o2}.
simple destruct o1; simple destruct o2; try auto;
try (right; red in |- *; intro; inversion H).