src/HOL/Auth/Yahalom2.thy

           ==> Says A B {|Agent A, Nonce NA|} # evs : yahalom lost"
 
          (*Bob's response to Alice's message.  Bob doesn't know who 
 	   the sender is, hence the A' in the sender field.*)
     YM2  "[| evs: yahalom lost;  B ~= Server;  Nonce NB ~: used evs;
-             Says A' B {|Agent A, Nonce NA|} : set_of_list evs |]
+             Says A' B {|Agent A, Nonce NA|} : set evs |]
           ==> Says B Server 
                   {|Agent B, Nonce NB, Crypt (shrK B) {|Agent A, Nonce NA|}|}
                 # evs : yahalom lost"
 
          (*The Server receives Bob's message.  He responds by sending a
            new session key to Alice, with a packet for forwarding to Bob.
            !! Fields are reversed in the 2nd packet to prevent attacks!! *)
     YM3  "[| evs: yahalom lost;  A ~= B;  A ~= Server;  Key KAB ~: used evs;
              Says B' Server {|Agent B, Nonce NB,
 			      Crypt (shrK B) {|Agent A, Nonce NA|}|}
-               : set_of_list evs |]
+               : set evs |]
           ==> Says Server A
                {|Nonce NB, 
                  Crypt (shrK A) {|Agent B, Key KAB, Nonce NA|},
                  Crypt (shrK B) {|Nonce NB, Key KAB, Agent A|}|}
                  # evs : yahalom lost"

          (*Alice receives the Server's (?) message, checks her Nonce, and
            uses the new session key to send Bob his Nonce.*)
     YM4  "[| evs: yahalom lost;  A ~= Server;  A ~= B;  
              Says S A {|Nonce NB, Crypt (shrK A) {|Agent B, Key K, Nonce NA|},
                         X|}
-               : set_of_list evs;
-             Says A B {|Agent A, Nonce NA|} : set_of_list evs |]
+               : set evs;
+             Says A B {|Agent A, Nonce NA|} : set evs |]
           ==> Says A B {|X, Crypt K (Nonce NB)|} # evs : yahalom lost"
 
          (*This message models possible leaks of session keys.  The nonces
            identify the protocol run.  Quoting Server here ensures they are
            correct. *)
     Oops "[| evs: yahalom lost;  A ~= Spy;
              Says Server A {|Nonce NB, 
                              Crypt (shrK A) {|Agent B, Key K, Nonce NA|},
-                             X|}  : set_of_list evs |]
+                             X|}  : set evs |]
           ==> Says A Spy {|Nonce NA, Nonce NB, Key K|} # evs : yahalom lost"
 
 end