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(* 02110-1301 USA                                                     *)

Theorem switch_subs :
forall (P : proc) (n1 n2 : name) (p : PP) (x : VV),
pname p <> n1 ->
vname x <> n2 ->
subs_var_proc (subs_par_proc P n2 p) n1 x =
subs_par_proc (subs_var_proc P n1 x) n2 p.