src/HOL/Auth/OtwayRees.thy

     Fake "[| evs: otway;  B ~= Spy;  
              X: synth (analz (sees Spy evs)) |]
           ==> Says Spy B X  # evs : otway"
 
          (*Alice initiates a protocol run*)
-    OR1  "[| evs: otway;  A ~= B;  B ~= Server;  Nonce NA ~: used evs |]
+    OR1  "[| evs1: otway;  A ~= B;  B ~= Server;  Nonce NA ~: used evs1 |]
           ==> Says A B {|Nonce NA, Agent A, Agent B, 
                          Crypt (shrK A) {|Nonce NA, Agent A, Agent B|} |} 
-                 # evs : otway"
+                 # evs1 : otway"
 
          (*Bob's response to Alice's message.  Bob doesn't know who 
 	   the sender is, hence the A' in the sender field.
            Note that NB is encrypted.*)
-    OR2  "[| evs: otway;  B ~= Server;  Nonce NB ~: used evs;
-             Says A' B {|Nonce NA, Agent A, Agent B, X|} : set evs |]
+    OR2  "[| evs2: otway;  B ~= Server;  Nonce NB ~: used evs2;
+             Says A' B {|Nonce NA, Agent A, Agent B, X|} : set evs2 |]
           ==> Says B Server 
                   {|Nonce NA, Agent A, Agent B, X, 
                     Crypt (shrK B)
                       {|Nonce NA, Nonce NB, Agent A, Agent B|}|}
-                 # evs : otway"
+                 # evs2 : otway"
 
          (*The Server receives Bob's message and checks that the three NAs
            match.  Then he sends a new session key to Bob with a packet for
            forwarding to Alice.*)
-    OR3  "[| evs: otway;  B ~= Server;  Key KAB ~: used evs;
+    OR3  "[| evs3: otway;  B ~= Server;  Key KAB ~: used evs3;
              Says B' Server 
                   {|Nonce NA, Agent A, Agent B, 
                     Crypt (shrK A) {|Nonce NA, Agent A, Agent B|}, 
                     Crypt (shrK B) {|Nonce NA, Nonce NB, Agent A, Agent B|}|}
-               : set evs |]
+               : set evs3 |]
           ==> Says Server B 
                   {|Nonce NA, 
                     Crypt (shrK A) {|Nonce NA, Key KAB|},
                     Crypt (shrK B) {|Nonce NB, Key KAB|}|}
-                 # evs : otway"
+                 # evs3 : otway"
 
          (*Bob receives the Server's (?) message and compares the Nonces with
 	   those in the message he previously sent the Server.*)
-    OR4  "[| evs: otway;  A ~= B;  
+    OR4  "[| evs4: otway;  A ~= B;  
              Says B Server {|Nonce NA, Agent A, Agent B, X', 
                              Crypt (shrK B)
                                    {|Nonce NA, Nonce NB, Agent A, Agent B|}|}
-               : set evs;
+               : set evs4;
              Says S' B {|Nonce NA, X, Crypt (shrK B) {|Nonce NB, Key K|}|}
-               : set evs |]
-          ==> Says B A {|Nonce NA, X|} # evs : otway"
+               : set evs4 |]
+          ==> Says B A {|Nonce NA, X|} # evs4 : otway"
 
          (*This message models possible leaks of session keys.  The nonces
            identify the protocol run.*)
-    Oops "[| evs: otway;  B ~= Spy;
+    Oops "[| evso: otway;  B ~= Spy;
              Says Server B {|Nonce NA, X, Crypt (shrK B) {|Nonce NB, Key K|}|}
-               : set evs |]
-          ==> Says B Spy {|Nonce NA, Nonce NB, Key K|} # evs : otway"
+               : set evso |]
+          ==> Says B Spy {|Nonce NA, Nonce NB, Key K|} # evso : otway"
 
 end