Directory example is now called NTP
authornipkow
Thu, 13 Apr 1995 16:57:18 +0200
changeset 1051 4fcd0638e61d
parent 1050 0c36c6a52a1d
child 1052 e044350bfa52
Directory example is now called NTP
src/HOL/IOA/NTP/Abschannel.ML
src/HOL/IOA/NTP/Abschannel.thy
src/HOL/IOA/NTP/Action.ML
src/HOL/IOA/NTP/Action.thy
src/HOL/IOA/NTP/Correctness.ML
src/HOL/IOA/NTP/Correctness.thy
src/HOL/IOA/NTP/Impl.ML
src/HOL/IOA/NTP/Impl.thy
src/HOL/IOA/NTP/Lemmas.ML
src/HOL/IOA/NTP/Lemmas.thy
src/HOL/IOA/NTP/Multiset.ML
src/HOL/IOA/NTP/Multiset.thy
src/HOL/IOA/NTP/Packet.ML
src/HOL/IOA/NTP/Packet.thy
src/HOL/IOA/NTP/Read_me
src/HOL/IOA/NTP/Receiver.ML
src/HOL/IOA/NTP/Receiver.thy
src/HOL/IOA/NTP/Sender.ML
src/HOL/IOA/NTP/Sender.thy
src/HOL/IOA/NTP/Spec.thy
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/HOL/IOA/NTP/Abschannel.ML	Thu Apr 13 16:57:18 1995 +0200
@@ -0,0 +1,54 @@
+(*  Title:      HOL/IOA/NTP/Abschannel.ML
+    ID:         $Id$
+    Author:     Tobias Nipkow and Olaf Mueller
+    Copyright   1994  TU Muenchen
+
+Derived rules
+*)
+
+open Abschannel;
+
+val abschannel_ss = action_ss addsimps 
+ ([srch_asig_def, rsch_asig_def, rsch_ioa_def, srch_ioa_def, ch_ioa_def, 
+   ch_asig_def, srch_actions_def, rsch_actions_def, rename_def, asig_of_def, 
+   actions_def, srch_trans_def, rsch_trans_def, ch_trans_def,starts_of_def, 
+   trans_of_def] 
+   @ Option.option.simps @ act.simps @ asig_projections @ set_lemmas);
+
+goal Abschannel.thy
+     "S_msg(m) ~: actions(srch_asig)        &    \
+     \ R_msg(m) ~: actions(srch_asig)        &    \
+     \ S_pkt(pkt) : actions(srch_asig)    &    \
+     \ R_pkt(pkt) : actions(srch_asig)    &    \
+     \ S_ack(b) ~: actions(srch_asig)     &    \
+     \ R_ack(b) ~: actions(srch_asig)     &    \
+     \ C_m_s ~: actions(srch_asig)           &    \
+     \ C_m_r ~: actions(srch_asig)           &    \
+     \ C_r_s ~: actions(srch_asig)  & C_r_r(m) ~: actions(srch_asig)";
+
+by(simp_tac abschannel_ss 1);
+qed"in_srch_asig";
+
+goal Abschannel.thy
+      "S_msg(m) ~: actions(rsch_asig)         & \
+     \ R_msg(m) ~: actions(rsch_asig)         & \
+     \ S_pkt(pkt) ~: actions(rsch_asig)    & \
+     \ R_pkt(pkt) ~: actions(rsch_asig)    & \
+     \ S_ack(b) : actions(rsch_asig)       & \
+     \ R_ack(b) : actions(rsch_asig)       & \
+     \ C_m_s ~: actions(rsch_asig)            & \
+     \ C_m_r ~: actions(rsch_asig)            & \
+     \ C_r_s ~: actions(rsch_asig)            & \
+     \ C_r_r(m) ~: actions(rsch_asig)";
+
+by(simp_tac abschannel_ss 1);
+qed"in_rsch_asig";
+
+goal Abschannel.thy "srch_ioa = (srch_asig, {{|}}, srch_trans)";
+by (simp_tac (abschannel_ss  addsimps [starts_of_def]) 1);
+qed"srch_ioa_thm";
+
+goal Abschannel.thy "rsch_ioa = (rsch_asig, {{|}}, rsch_trans)";
+by (simp_tac (abschannel_ss  addsimps [starts_of_def]) 1);
+qed"rsch_ioa_thm";
+
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/HOL/IOA/NTP/Abschannel.thy	Thu Apr 13 16:57:18 1995 +0200
@@ -0,0 +1,103 @@
+(*  Title:      HOL/IOA/NTP/Abschannel.thy
+    ID:         $Id$
+    Author:     Tobias Nipkow and Olaf Mueller
+    Copyright   1994  TU Muenchen
+
+The (faulty) transmission channel (both directions)
+*)
+
+Abschannel = IOA + Action + Multiset +
+ 
+datatype ('a)act =   S('a) | R('a)
+
+consts
+ 
+ch_asig  :: "'a act signature"
+
+ch_trans :: "('a act, 'a multiset)transition set"
+
+ch_ioa   :: "('a act, 'a multiset)ioa"
+
+rsch_actions  :: "'m action => bool act option"
+srch_actions  :: "'m action =>(bool * 'm) act option"
+
+srch_asig, 
+rsch_asig  :: "'m action signature"
+
+srch_trans :: "('m action, 'm packet multiset)transition set"
+rsch_trans :: "('m action, bool multiset)transition set"
+
+srch_ioa   :: "('m action, 'm packet multiset)ioa"
+rsch_ioa   :: "('m action, bool multiset)ioa"   
+
+
+defs
+
+srch_asig_def "srch_asig == asig_of(srch_ioa)"
+rsch_asig_def "rsch_asig == asig_of(rsch_ioa)"
+
+srch_trans_def "srch_trans == trans_of(srch_ioa)"  
+rsch_trans_def "rsch_trans == trans_of(rsch_ioa)"
+
+srch_ioa_def "srch_ioa == rename ch_ioa srch_actions"
+rsch_ioa_def "rsch_ioa == rename ch_ioa rsch_actions"
+
+
+ch_asig_def "ch_asig == (UN b. {S(b)}, UN b. {R(b)}, {})"
+
+ch_trans_def "ch_trans ==                                       \
+\ {tr. let s = fst(tr);                                         \
+\          t = snd(snd(tr))                                     \
+\      in                                                       \
+\      case fst(snd(tr))                                        \
+\        of S(b) => t = addm s b |                            \
+\           R(b) => count s b ~= 0 & t = delm s b}"
+
+ch_ioa_def "ch_ioa == (ch_asig, {{|}}, ch_trans)"
+
+
+rsch_actions_def "rsch_actions (act) ==        \
+\	    case act of                \
+\           S_msg(m) => None |         \
+\	    R_msg(m) => None |         \
+\           S_pkt(packet) => None |    \
+\	    R_pkt(packet) => None |    \
+\	    S_ack(b) => Some(S(b)) |   \
+\	    R_ack(b) => Some(R(b)) |   \
+\           C_m_s =>  None  |          \
+\           C_m_r =>  None |           \
+\           C_r_s =>  None  |          \
+\           C_r_r(m) => None"
+
+srch_actions_def "srch_actions (act) ==         \
+\	    case act of                \
+\           S_msg(m) => None |         \
+\	    R_msg(m) => None |         \
+\           S_pkt(p) => Some(S(p)) |   \
+\	    R_pkt(p) => Some(R(p)) |   \
+\	    S_ack(b) => None |         \
+\	    R_ack(b) => None |         \
+\           C_m_s => None |            \
+\           C_m_r => None |            \
+\           C_r_s => None |            \
+\           C_r_r(m) => None"
+
+end  
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
+
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/HOL/IOA/NTP/Action.ML	Thu Apr 13 16:57:18 1995 +0200
@@ -0,0 +1,13 @@
+(*  Title:      HOL/IOA/NTP/Action.ML
+    ID:         $Id$
+    Author:     Tobias Nipkow & Konrad Slind
+    Copyright   1994  TU Muenchen
+
+Derived rules for actions
+*)
+
+goal Action.thy "!!x. x = y ==> action_case a b c d e f g h i j x =     \
+\                               action_case a b c d e f g h i j y";
+by (asm_simp_tac HOL_ss 1);
+
+val action_ss = arith_ss addcongs [result()] addsimps Action.action.simps;
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/HOL/IOA/NTP/Action.thy	Thu Apr 13 16:57:18 1995 +0200
@@ -0,0 +1,14 @@
+(*  Title:      HOL/IOA/NTP/Action.thy
+    ID:         $Id$
+    Author:     Tobias Nipkow & Konrad Slind
+    Copyright   1994  TU Muenchen
+
+The set of all actions of the system
+*)
+
+Action = Packet +
+datatype 'm action = S_msg ('m) | R_msg ('m)
+                   | S_pkt ('m packet) | R_pkt ('m packet)
+                   | S_ack (bool) | R_ack (bool)
+                   | C_m_s | C_m_r | C_r_s | C_r_r ('m)
+end
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/HOL/IOA/NTP/Correctness.ML	Thu Apr 13 16:57:18 1995 +0200
@@ -0,0 +1,116 @@
+(*  Title:      HOL/IOA/NTP/Correctness.ML
+    ID:         $Id$
+    Author:     Tobias Nipkow & Konrad Slind
+    Copyright   1994  TU Muenchen
+
+The main correctness proof: Impl implements Spec
+*)
+
+open Impl;
+open Spec;
+
+val hom_ss = impl_ss;
+val hom_ioas = [Spec.ioa_def, Spec.trans_def,
+                Sender.sender_trans_def,Receiver.receiver_trans_def]
+               @ impl_ioas;
+
+val hom_ss' = hom_ss addsimps hom_ioas;
+
+val impl_asigs = [Sender.sender_asig_def,Receiver.receiver_asig_def,
+                   Abschannel.srch_asig_def,Abschannel.rsch_asig_def];
+
+
+(* A lemma about restricting the action signature of the implementation
+ * to that of the specification.
+ ****************************)
+goal Correctness.thy
+ "a:externals(asig_of(restrict impl_ioa (externals spec_sig))) = \
+\ (case a of                  \
+\     S_msg(m) => True        \
+\   | R_msg(m) => True        \
+\   | S_pkt(pkt) => False  \
+\   | R_pkt(pkt) => False  \
+\   | S_ack(b) => False    \
+\   | R_ack(b) => False    \
+\   | C_m_s => False          \
+\   | C_m_r => False          \
+\   | C_r_s => False          \
+\   | C_r_r(m) => False)";
+ by(simp_tac (hom_ss addcongs [if_weak_cong] 
+                  addsimps ([externals_def, restrict_def, restrict_asig_def,
+                             Spec.sig_def] @ asig_projections)) 1);
+
+  by(Action.action.induct_tac "a" 1);
+  by(ALLGOALS(simp_tac (action_ss addsimps 
+                        (actions_def :: asig_projections @ set_lemmas))));
+ (* 2 *)
+  by (simp_tac (hom_ss addsimps impl_ioas) 1);
+  by (simp_tac (hom_ss addsimps impl_asigs) 1); 
+  by(simp_tac (hom_ss addsimps ([asig_of_par, asig_comp_def] 
+                                 @ asig_projections)) 1);
+  by (simp_tac abschannel_ss 1); 
+ (* 1 *)
+  by (simp_tac (hom_ss addsimps impl_ioas) 1);
+  by (simp_tac (hom_ss addsimps impl_asigs) 1); 
+  by(simp_tac (hom_ss addsimps ([asig_of_par, asig_comp_def] 
+                                 @ asig_projections)) 1);
+  by (simp_tac abschannel_ss 1);
+qed "externals_lemma"; 
+
+
+val sels = [Sender.sbit_def, Sender.sq_def, Sender.ssending_def,
+            Receiver.rbit_def, Receiver.rq_def, Receiver.rsending_def];
+
+(* Proof of correctness *)
+goalw Correctness.thy [Spec.ioa_def, Solve.is_weak_pmap_def]
+  "is_weak_pmap hom (restrict impl_ioa (externals spec_sig)) spec_ioa";
+by(simp_tac (hom_ss addsimps 
+             (Correctness.hom_def::[cancel_restrict,externals_lemma])) 1);
+br conjI 1;
+by(simp_tac (hom_ss addsimps impl_ioas) 1);
+br ballI 1;
+bd CollectD 1;
+by(asm_simp_tac (hom_ss addsimps sels) 1);
+by(REPEAT(rtac allI 1));
+br imp_conj_lemma 1;   (* from lemmas.ML *)
+by(Action.action.induct_tac "a"  1);
+by(asm_simp_tac (hom_ss' setloop (split_tac [expand_if])) 1);
+by(forward_tac [inv4] 1);
+by(asm_full_simp_tac (hom_ss addsimps 
+                      [imp_ex_equiv,neq_Nil_conv,ex_all_equiv]) 1);
+by(simp_tac hom_ss' 1);
+by(simp_tac hom_ss' 1);
+by(simp_tac hom_ss' 1);
+by(simp_tac hom_ss' 1);
+by(simp_tac hom_ss' 1);
+by(simp_tac hom_ss' 1);
+by(simp_tac hom_ss' 1);
+
+by(asm_simp_tac hom_ss' 1);
+by(forward_tac [inv4] 1);
+by(forward_tac [inv2] 1);
+be disjE 1;
+by(asm_simp_tac hom_ss 1);
+by(asm_full_simp_tac (hom_ss addsimps 
+                      [imp_ex_equiv,neq_Nil_conv,ex_all_equiv]) 1);
+
+by(asm_simp_tac hom_ss' 1);
+by(forward_tac [inv2] 1);
+be disjE 1;
+
+by(forward_tac [inv3] 1);
+by(case_tac "sq(sen(s))=[]" 1);
+
+by(asm_full_simp_tac hom_ss' 1);
+by(fast_tac (HOL_cs addSDs [add_leD1 RS leD]) 1);
+
+by(case_tac "m = hd(sq(sen(s)))" 1);
+
+by(asm_full_simp_tac (hom_ss addsimps 
+                     [imp_ex_equiv,neq_Nil_conv,ex_all_equiv]) 1);
+
+by(asm_full_simp_tac hom_ss 1);
+by(fast_tac (HOL_cs addSDs [add_leD1 RS leD]) 1);
+
+by(asm_full_simp_tac hom_ss 1);
+result();
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/HOL/IOA/NTP/Correctness.thy	Thu Apr 13 16:57:18 1995 +0200
@@ -0,0 +1,21 @@
+(*  Title:      HOL/IOA/NTP/Correctness.thy
+    ID:         $Id$
+    Author:     Tobias Nipkow & Konrad Slind
+    Copyright   1994  TU Muenchen
+
+The main correctness proof: Impl implements Spec
+*)
+
+Correctness = Solve + Impl + Spec +
+
+consts
+
+hom :: "'m impl_state => 'm list"
+
+defs
+
+hom_def 
+"hom(s) == rq(rec(s)) @ (if rbit(rec s) = sbit(sen s) then sq(sen s) \
+\                        else ttl(sq(sen s)))"
+
+end
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/HOL/IOA/NTP/Impl.ML	Thu Apr 13 16:57:18 1995 +0200
@@ -0,0 +1,408 @@
+(*  Title:      HOL/IOA/NTP/Impl.ML
+    ID:         $Id$
+    Author:     Tobias Nipkow & Konrad Slind
+    Copyright   1994  TU Muenchen
+
+The implementation --- Invariants
+*)
+
+open Abschannel;
+
+val impl_ioas =
+  [Impl.impl_def,
+   Sender.sender_ioa_def, 
+   Receiver.receiver_ioa_def, 
+   srch_ioa_thm RS eq_reflection,
+   rsch_ioa_thm RS eq_reflection];
+
+val transitions = [Sender.sender_trans_def, Receiver.receiver_trans_def,
+            Abschannel.srch_trans_def, Abschannel.rsch_trans_def];
+ 
+
+val impl_ss = merge_ss(action_ss,list_ss) 
+              addcongs [let_weak_cong] 
+              addsimps [Let_def, ioa_triple_proj, starts_of_par, trans_of_par4,
+                       in_sender_asig, in_receiver_asig, in_srch_asig,
+                       in_rsch_asig, count_addm_simp, count_delm_simp,
+                       Multiset.countm_empty_def, Multiset.delm_empty_def,
+                       (* Multiset.count_def, *) count_empty,
+                       Packet.hdr_def, Packet.msg_def];
+
+goal Impl.thy
+  "fst(x) = sen(x)            & \
+\  fst(snd(x)) = rec(x)       & \
+\  fst(snd(snd(x))) = srch(x) & \
+\  snd(snd(snd(x))) = rsch(x)";
+by(simp_tac (HOL_ss addsimps
+        [Impl.sen_def,Impl.rec_def,Impl.srch_def,Impl.rsch_def]) 1);
+val impl_ss = impl_ss addsimps [result()];
+
+goal Impl.thy "a:actions(sender_asig)   \
+\            | a:actions(receiver_asig) \
+\            | a:actions(srch_asig)     \
+\            | a:actions(rsch_asig)";
+  by(Action.action.induct_tac "a" 1);
+  by(ALLGOALS(simp_tac impl_ss));
+val impl_ss = impl_ss addsimps [result()];
+
+
+(* INVARIANT 1 *)
+val ss = impl_ss addcongs [if_weak_cong] addsimps transitions;
+val abs_ss= merge_ss(ss,abschannel_ss);
+
+goalw Impl.thy impl_ioas "invariant impl_ioa inv1";
+br invariantI 1;
+by(asm_full_simp_tac (impl_ss addsimps 
+       [Impl.inv1_def, Impl.hdr_sum_def,
+        Sender.srcvd_def, Sender.ssent_def,
+        Receiver.rsent_def,Receiver.rrcvd_def]) 1);
+
+by(simp_tac (HOL_ss addsimps [fork_lemma,Impl.inv1_def]) 1);
+
+(* Split proof in two *)
+by (rtac conjI 1);
+
+(* First half *)
+by(asm_full_simp_tac (impl_ss addsimps [Impl.inv1_def]) 1);
+br Action.action.induct 1;
+
+val tac = asm_simp_tac (ss addcongs [conj_cong] 
+                           addsimps [Suc_pred_lemma]
+                           setloop (split_tac [expand_if]));
+val tac_abs = asm_simp_tac (abs_ss addcongs [conj_cong] 
+                                addsimps [Suc_pred_lemma]
+                                setloop (split_tac [expand_if]));
+by (EVERY1[tac, tac, tac, tac]);
+by (tac 1);
+by (tac_abs 1);
+
+(* 5 + 1 *)
+ 
+by (tac 1);
+by (tac_abs 1);
+ 
+(* 4 + 1 *)
+by(EVERY1[tac, tac, tac, tac]);
+
+
+(* Now the other half *)
+by(asm_full_simp_tac (impl_ss addsimps [Impl.inv1_def]) 1);
+br Action.action.induct 1;
+by(EVERY1[tac, tac]);
+
+(* detour 1 *)
+by (tac 1);
+by (tac_abs 1);
+by (rtac impI 1);
+by (REPEAT (etac conjE 1));
+by (asm_simp_tac (impl_ss addsimps [Impl.hdr_sum_def, Multiset.count_def,
+                                    Multiset.countm_nonempty_def]
+                          setloop (split_tac [expand_if])) 1);
+(* detour 2 *)
+by (tac 1);
+by (tac_abs 1);
+by (rtac impI 1);
+by (REPEAT (etac conjE 1));
+by (asm_full_simp_tac (impl_ss addsimps 
+                       [Impl.hdr_sum_def, 
+                        Multiset.count_def,
+                        Multiset.countm_nonempty_def,
+                        Multiset.delm_nonempty_def,
+                        left_plus_cancel,left_plus_cancel_inside_succ,
+                        unzero_less]
+                 setloop (split_tac [expand_if])) 1);
+by (rtac allI 1);
+by (rtac conjI 1);
+by (rtac impI 1);
+by (hyp_subst_tac 1);
+
+by (rtac (pred_suc RS mp RS sym RS iffD2) 1);
+by (dtac less_le_trans 1);
+by (cut_facts_tac [rewrite_rule[Packet.hdr_def]
+		   eq_packet_imp_eq_hdr RS countm_props] 1);;
+by (assume_tac 1);
+by (assume_tac 1);
+
+by (rtac (countm_done_delm RS mp RS sym) 1);
+by (rtac refl 1);
+by (asm_simp_tac (HOL_ss addsimps [Multiset.count_def]) 1);
+
+by (rtac impI 1);
+by (asm_full_simp_tac (HOL_ss addsimps [neg_flip]) 1);
+by (hyp_subst_tac 1);
+by (rtac countm_spurious_delm 1);
+by (simp_tac HOL_ss 1);
+
+by (EVERY1[tac, tac, tac, tac, tac, tac]);
+
+qed "inv1";
+
+
+
+(* INVARIANT 2 *)
+
+  goal Impl.thy "invariant impl_ioa inv2";
+
+  by (rtac invariantI1 1); 
+  (* Base case *)
+  by (asm_full_simp_tac (impl_ss addsimps 
+                    (Impl.inv2_def :: (receiver_projections 
+                                       @ sender_projections @ impl_ioas))) 1);
+
+  by (asm_simp_tac (impl_ss addsimps impl_ioas) 1);
+  by (Action.action.induct_tac "a" 1);
+
+  (* 10 cases. First 4 are simple, since state doesn't change wrt. invariant *)
+  (* 10 *)
+  by (asm_simp_tac (impl_ss addsimps (Impl.inv2_def::transitions)) 1);
+  (* 9 *)
+  by (asm_simp_tac (impl_ss addsimps (Impl.inv2_def::transitions)) 1);
+  (* 8 *)
+  by (asm_simp_tac (impl_ss addsimps (Impl.inv2_def::transitions)) 2);
+  (* 7 *)
+  by (asm_simp_tac (impl_ss addsimps (Impl.inv2_def::transitions)) 3);
+  (* 6 *)
+  by(forward_tac [rewrite_rule [Impl.inv1_def]
+                               (inv1 RS invariantE) RS conjunct1] 1);
+  by (asm_full_simp_tac (impl_ss addsimps [leq_imp_leq_suc,Impl.inv2_def]
+                                 addsimps transitions) 1);
+  (* 5 *)
+  by (asm_full_simp_tac (impl_ss addsimps [leq_imp_leq_suc,Impl.inv2_def]
+                                 addsimps transitions) 1);
+  (* 4 *)
+  by (forward_tac [rewrite_rule [Impl.inv1_def]
+                                (inv1 RS invariantE) RS conjunct1] 1);
+  by (asm_full_simp_tac (impl_ss addsimps [Impl.inv2_def] 
+                                 addsimps transitions) 1);
+  by (fast_tac (HOL_cs addDs [add_leD1,leD]) 1);
+
+  (* 3 *)
+  by (forward_tac [rewrite_rule [Impl.inv1_def] (inv1 RS invariantE)] 1);
+
+  by (asm_full_simp_tac (impl_ss addsimps 
+                         (Impl.inv2_def::transitions)) 1);
+  by (fold_tac [rewrite_rule [Packet.hdr_def]Impl.hdr_sum_def]);
+  by (fast_tac (HOL_cs addDs [add_leD1,leD]) 1);
+
+  (* 2 *)
+  by (asm_full_simp_tac (impl_ss addsimps 
+                         (Impl.inv2_def::transitions)) 1);
+  by(forward_tac [rewrite_rule [Impl.inv1_def]
+                               (inv1 RS invariantE) RS conjunct1] 1);
+  by (rtac impI 1);
+  by (rtac impI 1);
+  by (REPEAT (etac conjE 1));
+  by (dres_inst_tac [("k","count (rsch s) (~sbit(sen s))")] 
+                     (standard(leq_add_leq RS mp)) 1);
+  by (asm_full_simp_tac HOL_ss 1);
+
+  (* 1 *)
+  by (asm_full_simp_tac (impl_ss addsimps 
+                         (Impl.inv2_def::transitions)) 1);
+  by(forward_tac [rewrite_rule [Impl.inv1_def]
+                               (inv1 RS invariantE) RS conjunct2] 1);
+  by (rtac impI 1);
+  by (rtac impI 1);
+  by (REPEAT (etac conjE 1));
+  by (fold_tac  [rewrite_rule[Packet.hdr_def]Impl.hdr_sum_def]);
+  by (dres_inst_tac [("k","hdr_sum (srch s) (sbit(sen s))")] 
+                     (standard(leq_add_leq RS mp)) 1);
+  by (asm_full_simp_tac HOL_ss 1);
+qed "inv2";
+
+
+(* INVARIANT 3 *)
+goal Impl.thy "invariant impl_ioa inv3";
+
+  by (rtac invariantI 1); 
+  (* Base case *)
+  by (asm_full_simp_tac (impl_ss addsimps 
+                    (Impl.inv3_def :: (receiver_projections 
+                                       @ sender_projections @ impl_ioas))) 1);
+
+  by (asm_simp_tac (impl_ss addsimps impl_ioas) 1);
+  by (Action.action.induct_tac "a" 1);
+
+  (* 10 *)
+  by (asm_full_simp_tac (impl_ss addsimps 
+                  (append_cons::not_hd_append::Impl.inv3_def::transitions)
+                  setloop (split_tac [expand_if])) 1);
+
+  (* 9 *)
+  by (asm_full_simp_tac (impl_ss addsimps 
+                  (append_cons::not_hd_append::Impl.inv3_def::transitions)
+                  setloop (split_tac [expand_if])) 1);
+
+  (* 8 *)
+  by (asm_full_simp_tac (impl_ss addsimps 
+                  (append_cons::not_hd_append::Impl.inv3_def::transitions)
+                  setloop (split_tac [expand_if])) 1);
+  by (tac_abs 1);
+  by (strip_tac  1 THEN REPEAT (etac conjE 1));
+  by (asm_full_simp_tac (HOL_ss addsimps [cons_imp_not_null]) 1);
+
+
+  by (hyp_subst_tac 1);
+  by (etac exE 1);
+  by (asm_full_simp_tac list_ss 1);
+
+  (* 7 *)
+  by (asm_full_simp_tac (impl_ss addsimps 
+      (Suc_pred_lemma::append_cons::not_hd_append::Impl.inv3_def::transitions)
+                  setloop (split_tac [expand_if])) 1); 
+  by (tac_abs 1);
+  by (fast_tac HOL_cs 1);
+
+  (* 6 *)
+  by (asm_full_simp_tac (impl_ss addsimps 
+                  (append_cons::not_hd_append::Impl.inv3_def::transitions)
+                  setloop (split_tac [expand_if])) 1);
+  (* 5 *)
+  by (asm_full_simp_tac (impl_ss addsimps 
+                  (append_cons::not_hd_append::Impl.inv3_def::transitions)
+                  setloop (split_tac [expand_if])) 1);
+
+  (* 4 *)
+  by (asm_full_simp_tac (impl_ss addsimps 
+                  (append_cons::not_hd_append::Impl.inv3_def::transitions)
+                  setloop (split_tac [expand_if])) 1);
+
+  (* 3 *)
+  by (asm_full_simp_tac (impl_ss addsimps 
+                  (append_cons::not_hd_append::Impl.inv3_def::transitions)
+                  setloop (split_tac [expand_if])) 1);
+
+  (* 2 *)
+  by (asm_full_simp_tac (impl_ss addsimps transitions) 1);
+  by (simp_tac (HOL_ss addsimps [Impl.inv3_def]) 1);
+  by (strip_tac  1 THEN REPEAT (etac conjE 1));
+  by (rtac (imp_or_lem RS iffD2) 1);
+  by (rtac impI 1);
+  by (forward_tac [rewrite_rule [Impl.inv2_def] (inv2 RS invariantE)] 1);
+  by (asm_full_simp_tac list_ss 1);
+  by (REPEAT (etac conjE 1));
+  by (res_inst_tac [("j","count (ssent(sen s)) (~sbit(sen s))"),
+                    ("k","count (rsent(rec s)) (sbit(sen s))")] le_trans 1);
+  by (forward_tac [rewrite_rule [Impl.inv1_def]
+                                (inv1 RS invariantE) RS conjunct2] 1);
+  by (asm_full_simp_tac (list_ss addsimps 
+                         [Impl.hdr_sum_def, Multiset.count_def]) 1);
+  by (rtac (less_eq_add_cong RS mp RS mp) 1);
+  by (rtac countm_props 1);
+  by (simp_tac (list_ss addsimps [Packet.hdr_def]) 1);
+  by (rtac countm_props 1);
+  by (simp_tac (list_ss addsimps [Packet.hdr_def]) 1);
+  by (assume_tac 1);
+
+
+  (* 1 *)
+  by (asm_full_simp_tac (impl_ss addsimps 
+                  (append_cons::not_hd_append::Impl.inv3_def::transitions)
+                  setloop (split_tac [expand_if])) 1);
+  by (strip_tac  1 THEN REPEAT (etac conjE 1));
+  by (rtac (imp_or_lem RS iffD2) 1);
+  by (rtac impI 1);
+  by (forward_tac [rewrite_rule [Impl.inv2_def] (inv2 RS invariantE)] 1);
+  by (asm_full_simp_tac list_ss 1);
+  by (REPEAT (etac conjE 1));
+  by (dtac mp 1);
+  by (assume_tac 1);
+  by (etac allE 1);
+  by (dtac (imp_or_lem RS iffD1) 1);
+  by (dtac mp 1);
+  by (assume_tac 1);
+  by (assume_tac 1);
+qed "inv3";
+
+
+
+(* INVARIANT 4 *)
+
+goal Impl.thy "invariant impl_ioa inv4";
+
+  by (rtac invariantI 1); 
+  (* Base case *)
+  by (asm_full_simp_tac (impl_ss addsimps 
+                    (Impl.inv4_def :: (receiver_projections 
+                                       @ sender_projections @ impl_ioas))) 1);
+
+  by (asm_simp_tac (impl_ss addsimps impl_ioas) 1);
+  by (Action.action.induct_tac "a" 1);
+
+  (* 10 *)
+  by (asm_full_simp_tac (impl_ss addsimps 
+                         (append_cons::Impl.inv4_def::transitions)
+                  setloop (split_tac [expand_if])) 1);
+
+  (* 9 *)
+  by (asm_full_simp_tac (impl_ss addsimps 
+                         (append_cons::Impl.inv4_def::transitions)
+                  setloop (split_tac [expand_if])) 1);
+
+  (* 8 *)
+  by (asm_full_simp_tac (impl_ss addsimps 
+                         (append_cons::Impl.inv4_def::transitions)
+                  setloop (split_tac [expand_if])) 1);
+  (* 7 *)
+  by (asm_full_simp_tac (impl_ss addsimps 
+                         (append_cons::Impl.inv4_def::transitions)
+                  setloop (split_tac [expand_if])) 1);
+
+  (* 6 *)
+  by (asm_full_simp_tac (impl_ss addsimps 
+                         (append_cons::Impl.inv4_def::transitions)
+                  setloop (split_tac [expand_if])) 1);
+
+  (* 5 *)
+  by (asm_full_simp_tac (impl_ss addsimps 
+                         (append_cons::Impl.inv4_def::transitions)
+                  setloop (split_tac [expand_if])) 1);
+
+  (* 4 *)
+  by (asm_full_simp_tac (impl_ss addsimps 
+                         (append_cons::Impl.inv4_def::transitions)
+                  setloop (split_tac [expand_if])) 1);
+
+  (* 3 *)
+  by (asm_full_simp_tac (impl_ss addsimps 
+                         (append_cons::Impl.inv4_def::transitions)
+                  setloop (split_tac [expand_if])) 1);
+
+  (* 2 *)
+  by (asm_full_simp_tac (impl_ss addsimps 
+                         (append_cons::Impl.inv4_def::transitions)
+                  setloop (split_tac [expand_if])) 1);
+
+  by (strip_tac  1 THEN REPEAT (etac conjE 1));
+  by(forward_tac [rewrite_rule [Impl.inv2_def]
+                               (inv2 RS invariantE)] 1);
+ 
+  by (asm_full_simp_tac list_ss 1);
+
+  (* 1 *)
+  by (asm_full_simp_tac (impl_ss addsimps 
+                         (append_cons::Impl.inv4_def::transitions)
+                  setloop (split_tac [expand_if])) 1);
+  by (strip_tac  1 THEN REPEAT (etac conjE 1));
+  by (rtac ccontr 1);
+  by(forward_tac [rewrite_rule [Impl.inv2_def]
+                               (inv2 RS invariantE)] 1);
+  by(forward_tac [rewrite_rule [Impl.inv3_def]
+                               (inv3 RS invariantE)] 1);
+  by (asm_full_simp_tac list_ss 1);
+  by (eres_inst_tac [("x","m")] allE 1);
+  by (dtac less_le_trans 1);
+  by (dtac (left_add_leq RS mp) 1);
+  by (asm_full_simp_tac list_ss 1);
+  by (asm_full_simp_tac arith_ss 1);
+qed "inv4";
+
+
+
+(* rebind them *)
+
+val inv1 = rewrite_rule [Impl.inv1_def] (inv1 RS invariantE);
+val inv2 = rewrite_rule [Impl.inv2_def] (inv2 RS invariantE);
+val inv3 = rewrite_rule [Impl.inv3_def] (inv3 RS invariantE);
+val inv4 = rewrite_rule [Impl.inv4_def] (inv4 RS invariantE);
+
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/HOL/IOA/NTP/Impl.thy	Thu Apr 13 16:57:18 1995 +0200
@@ -0,0 +1,71 @@
+(*  Title:      HOL/IOA/NTP/Impl.thy
+    ID:         $Id$
+    Author:     Tobias Nipkow & Konrad Slind
+    Copyright   1994  TU Muenchen
+
+The implementation
+*)
+
+Impl = Sender + Receiver + Abschannel +
+
+types 
+
+'m impl_state 
+= "'m sender_state * 'm receiver_state * 'm packet multiset * bool multiset"
+(*  sender_state   *  receiver_state   *    srch_state      * rsch_state *)
+
+
+consts
+ impl_ioa    :: "('m action, 'm impl_state)ioa"
+ sen         :: "'m impl_state => 'm sender_state"
+ rec         :: "'m impl_state => 'm receiver_state"
+ srch        :: "'m impl_state => 'm packet multiset"
+ rsch        :: "'m impl_state => bool multiset"
+ inv1, inv2, 
+ inv3, inv4  :: "'m impl_state => bool"
+ hdr_sum     :: "'m packet multiset => bool => nat"
+
+defs
+
+ impl_def
+  "impl_ioa == (sender_ioa || receiver_ioa || srch_ioa || rsch_ioa)"
+
+ sen_def   "sen == fst"
+ rec_def   "rec == fst o snd"
+ srch_def "srch == fst o snd o snd"
+ rsch_def "rsch == snd o snd o snd"
+
+hdr_sum_def
+   "hdr_sum M b == countm M (%pkt.hdr(pkt) = b)"
+
+(* Lemma 5.1 *)
+inv1_def 
+  "inv1(s) ==                                                                 \
+ \   (!b. count (rsent(rec s)) b = count (srcvd(sen s)) b + count (rsch s) b) \
+ \ & (!b. count (ssent(sen s)) b                                              \
+ \        = hdr_sum (rrcvd(rec s)) b + hdr_sum (srch s) b)"
+
+(* Lemma 5.2 *)
+ inv2_def "inv2(s) ==                                                   \
+\  (rbit(rec(s)) = sbit(sen(s)) &                                       \
+\   ssending(sen(s)) &                                                  \
+\   count (rsent(rec s)) (~sbit(sen s)) <= count (ssent(sen s)) (~sbit(sen s)) &\
+\   count (ssent(sen s)) (~sbit(sen s)) <= count (rsent(rec s)) (sbit(sen s)))  \
+\   |                                                                   \
+\  (rbit(rec(s)) = (~sbit(sen(s))) &                                    \
+\   rsending(rec(s)) &                                                  \
+\   count (ssent(sen s)) (~sbit(sen s)) <= count (rsent(rec s)) (sbit(sen s)) &\
+\   count (rsent(rec s)) (sbit(sen s)) <= count (ssent(sen s)) (sbit(sen s)))"
+
+(* Lemma 5.3 *)
+ inv3_def "inv3(s) ==                                                   \
+\   rbit(rec(s)) = sbit(sen(s))                                         \
+\   --> (!m. sq(sen(s))=[] | m ~= hd(sq(sen(s)))                        \
+\        -->  count (rrcvd(rec s)) (sbit(sen(s)),m)                     \
+\             + count (srch s) (sbit(sen(s)),m)                         \
+\            <= count (rsent(rec s)) (~sbit(sen s)))"
+
+(* Lemma 5.4 *)
+ inv4_def "inv4(s) == rbit(rec(s)) = (~sbit(sen(s))) --> sq(sen(s)) ~= []"
+
+end
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/HOL/IOA/NTP/Lemmas.ML	Thu Apr 13 16:57:18 1995 +0200
@@ -0,0 +1,239 @@
+(*  Title:      HOL/IOA/NTP/Lemmas.ML
+    ID:         $Id$
+    Author:     Tobias Nipkow & Konrad Slind
+    Copyright   1994  TU Muenchen
+
+(Mostly) Arithmetic lemmas
+Should realy go in Arith.ML.
+Also: Get rid of all the --> in favour of ==> !!!
+*)
+
+(* Logic *)
+val prems = goal HOL.thy "(P ==> Q-->R) ==> P&Q --> R";
+  by(fast_tac (HOL_cs addDs prems) 1);
+qed "imp_conj_lemma";
+
+goal HOL.thy "(P --> (? x. Q(x))) = (? x. P --> Q(x))";
+  by(fast_tac HOL_cs 1);
+qed "imp_ex_equiv";
+
+goal HOL.thy "(A --> B & C) = ((A --> B) & (A --> C))";
+  by (fast_tac HOL_cs 1);
+qed "fork_lemma";
+
+goal HOL.thy "((A --> B) & (C --> B)) = ((A | C) --> B)";
+  by (fast_tac HOL_cs 1);
+qed "imp_or_lem";
+
+goal HOL.thy "(X = (~ Y)) = ((~X) = Y)";
+  by (fast_tac HOL_cs 1);
+qed "neg_flip";
+
+goal HOL.thy "P --> Q(M) --> Q(if P then M else N)";
+  by (rtac impI 1); 
+  by (rtac impI 1);
+  by (rtac (expand_if RS iffD2) 1);
+  by (fast_tac HOL_cs 1);
+qed "imp_true_decompose";
+
+goal HOL.thy "(~P) --> Q(N) --> Q(if P then M else N)";
+  by (rtac impI 1); 
+  by (rtac impI 1);
+  by (rtac (expand_if RS iffD2) 1);
+  by (fast_tac HOL_cs 1);
+qed "imp_false_decompose";
+
+
+(* Sets *)
+val set_lemmas =
+   map (fn s => prove_goal Set.thy s (fn _ => [fast_tac set_cs 1]))
+        ["f(x) : (UN x. {f(x)})",
+         "f x y : (UN x y. {f x y})",
+         "!!a. (!x. a ~= f(x)) ==> a ~: (UN x. {f(x)})",
+         "!!a. (!x y. a ~= f x y) ==> a ~: (UN x y. {f x y})"];
+
+
+(* Arithmetic *)
+goal Arith.thy "n ~= 0 --> Suc(m+pred(n)) = m+n";
+  by (nat_ind_tac "n" 1);
+  by (REPEAT(simp_tac arith_ss 1));
+val Suc_pred_lemma = store_thm("Suc_pred_lemma", result() RS mp);
+
+goal Arith.thy "x <= y --> x <= Suc(y)";
+  by (rtac impI 1);
+  by (rtac (le_eq_less_or_eq RS iffD2) 1);
+  by (rtac disjI1 1);
+  by (dtac (le_eq_less_or_eq RS iffD1) 1);
+  by (etac disjE 1);
+  by (etac less_SucI 1);
+  by (asm_simp_tac nat_ss 1);
+val leq_imp_leq_suc = store_thm("leq_imp_leq_suc", result() RS mp);
+
+(* Same as previous! *)
+goal Arith.thy "(x::nat)<=y --> x<=Suc(y)";
+  by (simp_tac (arith_ss addsimps [le_eq_less_or_eq]) 1);
+qed "leq_suc";
+
+goal Arith.thy "((m::nat) + n = m + p) = (n = p)";
+  by (nat_ind_tac "m" 1);
+  by (simp_tac arith_ss 1);
+  by (asm_simp_tac arith_ss 1);
+qed "left_plus_cancel";
+
+goal Arith.thy "((x::nat) + y = Suc(x + z)) = (y = Suc(z))";
+  by (nat_ind_tac "x" 1);
+  by (simp_tac arith_ss 1);
+  by (asm_simp_tac arith_ss 1);
+qed "left_plus_cancel_inside_succ";
+
+goal Arith.thy "(x ~= 0) = (? y. x = Suc(y))";
+  by (nat_ind_tac "x" 1);
+  by (simp_tac arith_ss 1);
+  by (asm_simp_tac arith_ss 1);
+  by (fast_tac HOL_cs 1);
+qed "nonzero_is_succ";
+
+goal Arith.thy "(m::nat) < n --> m + p < n + p";
+  by (nat_ind_tac "p" 1);
+  by (simp_tac arith_ss 1);
+  by (asm_simp_tac arith_ss 1);
+qed "less_add_same_less";
+
+goal Arith.thy "(x::nat)<= y --> x<=y+k";
+  by (nat_ind_tac "k" 1);
+  by (simp_tac arith_ss 1);
+  by (asm_full_simp_tac (arith_ss addsimps [leq_suc]) 1);
+qed "leq_add_leq";
+
+goal Arith.thy "(x::nat) + y <= z --> x <= z";
+  by (nat_ind_tac "y" 1);
+  by (simp_tac arith_ss 1);
+  by (asm_simp_tac arith_ss 1);
+  by (rtac impI 1);
+  by (dtac Suc_leD 1);
+  by (fast_tac HOL_cs 1);
+qed "left_add_leq";
+
+goal Arith.thy "(A::nat) < B --> C < D --> A + C < B + D";
+ by (rtac impI 1);
+ by (rtac impI 1);
+ by (rtac less_trans 1);
+ by (rtac (less_add_same_less RS mp) 1);
+ by (assume_tac 1);
+ by (rtac (add_commute RS ssubst)1);;
+ by (res_inst_tac [("m1","B")] (add_commute RS ssubst) 1);
+ by (rtac (less_add_same_less RS mp) 1);
+ by (assume_tac 1);
+qed "less_add_cong";
+
+goal Arith.thy "(A::nat) <= B --> C <= D --> A + C <= B + D";
+  by (rtac impI 1);
+  by (rtac impI 1);
+  by (asm_full_simp_tac (arith_ss addsimps [le_eq_less_or_eq]) 1);
+  by (safe_tac HOL_cs);
+  by (rtac (less_add_cong RS mp RS mp) 1);
+  by (assume_tac 1);
+  by (assume_tac 1);
+  by (rtac (less_add_same_less RS mp) 1);
+  by (assume_tac 1);
+  by (rtac (add_commute RS ssubst)1);;
+  by (res_inst_tac [("m1","B")] (add_commute RS ssubst) 1);
+  by (rtac (less_add_same_less RS mp) 1);
+  by (assume_tac 1);
+qed "less_eq_add_cong";
+
+goal Arith.thy "(w <= y) --> ((x::nat) + y <= z) --> (x + w <= z)";
+  by (rtac impI 1); 
+  by (dtac (less_eq_add_cong RS mp) 1);
+  by (cut_facts_tac [le_refl] 1);
+  by (dres_inst_tac [("P","x<=x")] mp 1);by (assume_tac 1);
+  by (asm_full_simp_tac (HOL_ss addsimps [add_commute]) 1);
+  by (rtac impI 1);
+  by (etac le_trans 1);
+  by (assume_tac 1);
+qed "leq_add_left_cong";
+
+goal Arith.thy "(? x. y = Suc(x)) = (~(y = 0))";
+  by (nat_ind_tac "y" 1);
+  by (simp_tac arith_ss 1);
+  by (rtac iffI 1);
+  by (asm_full_simp_tac arith_ss 1);
+  by (fast_tac HOL_cs 1);
+qed "suc_not_zero";
+
+goal Arith.thy "Suc(x) <= y --> (? z. y = Suc(z))";
+  by (rtac impI 1);
+  by (asm_full_simp_tac (arith_ss addsimps [le_eq_less_or_eq]) 1);
+  by (safe_tac HOL_cs);
+  by (fast_tac HOL_cs 2);
+  by (asm_simp_tac (arith_ss addsimps [suc_not_zero]) 1);
+  by (rtac ccontr 1);
+  by (asm_full_simp_tac (arith_ss addsimps [suc_not_zero]) 1);
+  by (hyp_subst_tac 1);
+  by (asm_full_simp_tac arith_ss 1);
+qed "suc_leq_suc";
+
+goal Arith.thy "~0<n --> n = 0";
+  by (nat_ind_tac "n" 1);
+  by (asm_simp_tac arith_ss 1);
+  by (safe_tac HOL_cs);
+  by (asm_full_simp_tac arith_ss 1);
+  by (asm_full_simp_tac arith_ss 1);
+qed "zero_eq";
+
+goal Arith.thy "x < Suc(y) --> x<=y";
+  by (nat_ind_tac "n" 1);
+  by (asm_simp_tac arith_ss 1);
+  by (safe_tac HOL_cs);
+  by (etac less_imp_le 1);
+qed "less_suc_imp_leq";
+
+goal Arith.thy "0<x --> Suc(pred(x)) = x";
+  by (nat_ind_tac "x" 1);
+  by (simp_tac arith_ss 1);
+  by (asm_simp_tac arith_ss 1);
+qed "suc_pred_id";
+
+goal Arith.thy "0<x --> (pred(x) = y) = (x = Suc(y))";
+  by (nat_ind_tac "x" 1);
+  by (simp_tac arith_ss 1);
+  by (asm_simp_tac arith_ss 1);
+qed "pred_suc";
+
+goal Arith.thy "(x ~= 0) = (0<x)";
+  by (nat_ind_tac "x" 1);
+  by (simp_tac arith_ss 1);
+  by (asm_simp_tac arith_ss 1);
+qed "unzero_less";
+
+(* Odd proof. Why do induction? *)
+goal Arith.thy "((x::nat) = y + z) --> (y <= x)";
+  by (nat_ind_tac "y" 1);
+  by (simp_tac arith_ss 1);
+  by (simp_tac (arith_ss addsimps 
+                [Suc_le_mono, le_refl RS (leq_add_leq RS mp)]) 1);
+qed "plus_leq_lem";
+
+(* Lists *)
+
+goal List.thy "(xs @ (y#ys)) ~= []";
+  by (list.induct_tac "xs" 1);
+  by (simp_tac list_ss 1);
+  by (asm_simp_tac list_ss 1);
+qed "append_cons";
+
+goal List.thy "(x ~= hd(xs@ys)) = (x ~= (if xs = [] then hd ys else hd xs))";
+  by (list.induct_tac "xs" 1);
+  by (simp_tac list_ss 1);
+  by (asm_full_simp_tac list_ss 1);
+qed "not_hd_append";
+
+goal List.thy "(L = (x#rst)) --> (L = []) --> P";
+  by (simp_tac list_ss 1);
+qed "list_cases";
+
+goal List.thy "(? L2. L1 = x#L2) --> (L1 ~= [])";
+  by (strip_tac 1);
+  by (etac exE 1);
+  by (asm_simp_tac list_ss 1);
+qed "cons_imp_not_null";
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/HOL/IOA/NTP/Lemmas.thy	Thu Apr 13 16:57:18 1995 +0200
@@ -0,0 +1,9 @@
+(*  Title:      HOL/IOA/NTP/Lemmas.thy
+    ID:         $Id$
+    Author:     Tobias Nipkow & Konrad Slind
+    Copyright   1994  TU Muenchen
+
+Arithmetic lemmas
+*)
+
+Lemmas = Arith
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/HOL/IOA/NTP/Multiset.ML	Thu Apr 13 16:57:18 1995 +0200
@@ -0,0 +1,84 @@
+(*  Title:      HOL/IOA/NTP/Multiset.ML
+    ID:         $Id$
+    Author:     Tobias Nipkow & Konrad Slind
+    Copyright   1994  TU Muenchen
+
+Axiomatic multisets.
+Should be done as a subtype and moved to a global place.
+*)
+
+goalw Multiset.thy [Multiset.count_def, Multiset.countm_empty_def]
+   "count {|} x = 0";
+ by (rtac refl 1);
+qed "count_empty";
+
+goal Multiset.thy 
+     "count (addm M x) y = (if y=x then Suc(count M y) else count M y)";
+  by (asm_simp_tac (arith_ss addsimps 
+                    [Multiset.count_def,Multiset.countm_nonempty_def]
+                    setloop (split_tac [expand_if])) 1);
+qed "count_addm_simp";
+
+goal Multiset.thy "count M y <= count (addm M x) y";
+  by (simp_tac (arith_ss addsimps [count_addm_simp]
+                         setloop (split_tac [expand_if])) 1);
+  by (rtac impI 1);
+  by (rtac (le_refl RS (leq_suc RS mp)) 1);
+qed "count_leq_addm";
+
+goalw Multiset.thy [Multiset.count_def] 
+     "count (delm M x) y = (if y=x then pred(count M y) else count M y)";
+  by (res_inst_tac [("M","M")] Multiset.induction 1);
+  by (asm_simp_tac (arith_ss 
+                   addsimps [Multiset.delm_empty_def,Multiset.countm_empty_def]
+                   setloop (split_tac [expand_if])) 1);
+  by (asm_full_simp_tac (arith_ss 
+                         addsimps [Multiset.delm_nonempty_def,
+                                   Multiset.countm_nonempty_def]
+                         setloop (split_tac [expand_if])) 1);
+  by (safe_tac HOL_cs);
+  by (asm_full_simp_tac HOL_ss 1);
+qed "count_delm_simp";
+
+goal Multiset.thy "!!M. (!x. P(x) --> Q(x)) ==> (countm M P <= countm M Q)";
+  by (res_inst_tac [("M","M")] Multiset.induction 1);
+  by (simp_tac (arith_ss addsimps [Multiset.countm_empty_def]) 1);
+  by (simp_tac (arith_ss addsimps[Multiset.countm_nonempty_def]) 1);
+  by (etac (less_eq_add_cong RS mp RS mp) 1);
+  by (asm_full_simp_tac (arith_ss addsimps [le_eq_less_or_eq]
+                                  setloop (split_tac [expand_if])) 1);
+qed "countm_props";
+
+goal Multiset.thy "!!P. ~P(obj) ==> countm M P = countm (delm M obj) P";
+  by (res_inst_tac [("M","M")] Multiset.induction 1);
+  by (simp_tac (arith_ss addsimps [Multiset.delm_empty_def,
+                                   Multiset.countm_empty_def]) 1);
+  by (asm_simp_tac (arith_ss addsimps[Multiset.countm_nonempty_def,
+                                      Multiset.delm_nonempty_def]
+                             setloop (split_tac [expand_if])) 1);
+qed "countm_spurious_delm";
+
+
+goal Multiset.thy "!!P. P(x) ==> 0<count M x --> 0<countm M P";
+  by (res_inst_tac [("M","M")] Multiset.induction 1);
+  by (simp_tac (arith_ss addsimps 
+                          [Multiset.delm_empty_def,Multiset.count_def,
+                           Multiset.countm_empty_def]) 1);
+  by (asm_simp_tac (arith_ss addsimps 
+                       [Multiset.count_def,Multiset.delm_nonempty_def,
+                        Multiset.countm_nonempty_def]
+                    setloop (split_tac [expand_if])) 1);
+val pos_count_imp_pos_countm = store_thm("pos_count_imp_pos_countm", standard(result() RS mp));
+
+goal Multiset.thy
+   "!!P. P(x) ==> 0<count M x --> countm (delm M x) P = pred (countm M P)";
+  by (res_inst_tac [("M","M")] Multiset.induction 1);
+  by (simp_tac (arith_ss addsimps 
+                          [Multiset.delm_empty_def,
+                           Multiset.countm_empty_def]) 1);
+  by (asm_simp_tac (arith_ss addsimps 
+                      [eq_sym_conv,count_addm_simp,Multiset.delm_nonempty_def,
+                       Multiset.countm_nonempty_def,pos_count_imp_pos_countm,
+                       suc_pred_id]
+                    setloop (split_tac [expand_if])) 1);
+qed "countm_done_delm";
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/HOL/IOA/NTP/Multiset.thy	Thu Apr 13 16:57:18 1995 +0200
@@ -0,0 +1,48 @@
+(*  Title:      HOL/IOA/NTP/Multiset.thy
+    ID:         $Id$
+    Author:     Tobias Nipkow & Konrad Slind
+    Copyright   1994  TU Muenchen
+
+Axiomatic multisets.
+Should be done as a subtype and moved to a global place.
+*)
+
+Multiset = Arith + "Lemmas" +
+
+types
+
+  'a multiset
+
+arities
+
+  multiset :: (term) term
+
+consts
+
+  "{|}"  :: "'a multiset"                        ("{|}")
+  addm   :: "['a multiset, 'a] => 'a multiset"
+  delm   :: "['a multiset, 'a] => 'a multiset"
+  countm :: "['a multiset, 'a => bool] => nat"
+  count  :: "['a multiset, 'a] => nat"
+
+rules
+
+delm_empty_def
+  "delm {|} x = {|}" 
+
+delm_nonempty_def
+  "delm (addm M x) y == (if x=y then M else addm (delm M y) x)"
+
+countm_empty_def
+   "countm {|} P == 0"
+
+countm_nonempty_def
+   "countm (addm M x) P == countm M P + (if P x then Suc 0 else 0)"
+
+count_def
+   "count M x == countm M (%y.y = x)"
+
+induction
+   "[| P({|}); !!M x. P(M) ==> P(addm M x) |] ==> P(M)"
+
+end
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/HOL/IOA/NTP/Packet.ML	Thu Apr 13 16:57:18 1995 +0200
@@ -0,0 +1,13 @@
+(*  Title:      HOL/IOA/NTP/Packet.ML
+    ID:         $Id$
+    Author:     Tobias Nipkow & Konrad Slind
+    Copyright   1994  TU Muenchen
+
+Packets
+*)
+
+
+(* Instantiation of a tautology? *)
+goal Packet.thy "!x. x = packet --> hdr(x) = hdr(packet)";
+ by (simp_tac (HOL_ss addsimps [Packet.hdr_def]) 1);
+qed "eq_packet_imp_eq_hdr"; 
\ No newline at end of file
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/HOL/IOA/NTP/Packet.thy	Thu Apr 13 16:57:18 1995 +0200
@@ -0,0 +1,25 @@
+(*  Title:      HOL/IOA/NTP/Packet.thy
+    ID:         $Id$
+    Author:     Tobias Nipkow & Konrad Slind
+    Copyright   1994  TU Muenchen
+
+Packets
+*)
+
+Packet = Arith +
+
+types
+
+   'msg packet = "bool * 'msg"
+
+consts
+
+  hdr  :: "'msg packet => bool"
+  msg :: "'msg packet => 'msg"
+
+defs
+
+  hdr_def "hdr == fst"
+  msg_def "msg == snd"
+
+end
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/HOL/IOA/NTP/Read_me	Thu Apr 13 16:57:18 1995 +0200
@@ -0,0 +1,182 @@
+Isabelle Verification of a protocol using IOA.
+
+------------------------------------------------------------------------------
+The theory structure looks like this picture:
+
+     Correctness
+
+        Impl
+
+Sender Receiver Channels Spec
+
+ Action    IOA      Multisets
+
+ Packet        List 
+
+         Arith
+
+------------------------------------------------------------------------------
+
+The System.
+
+The system being proved correct is a parallel composition of 4 processes:
+
+    Sender || Schannel || Receiver || Rchannel
+
+Accordingly, the system state is a 4-tuple:
+
+    (Sender_state, Schannel_state, Receiver_state, Rchannel_state)
+
+------------------------------------------------------------------------------
+Packets.
+
+The objects going over the medium from Sender to Receiver are modelled
+with the type
+
+    'm packet = bool * 'm
+
+This expresses that messages (modelled by polymorphic type "'m") are
+sent with a single header bit. Packet fields are accessed by
+
+    hdr<b,m> = b
+    mesg<b,m> = m
+------------------------------------------------------------------------------
+
+The Sender.
+
+The state of the process "Sender" is a 5-tuple:
+
+     1. messages : 'm list        (* sq *)
+     2. sent     : bool multiset  (* ssent *)
+     3. received : bool multiset  (* srcvd *)
+     4. header   : bool           (* sbit *)
+     5. mode     : bool           (* ssending *)
+
+
+The Receiver.
+
+The state of the process "Receiver" is a 5-tuple:
+
+     1. messages    : 'm list              (* rq *)
+     2. replies     : bool multiset        (* rsent *)
+     3. received    : 'm packet multiset   (* rrcvd *)
+     4. header      : bool                 (* rbit *)
+     5. mode        : bool                 (* rsending *)
+
+
+The Channels.
+
+The Sender and Receiver each have a proprietary channel, named
+"Schannel" and "Rchannel" respectively. The messages sent by the Sender
+and Receiver are never lost, but the channels may mix them
+up. Accordingly, multisets are used in modelling the state of the
+channels. The state of "Schannel" is modelled with the following type:
+
+    'm packet multiset
+
+The state of "Rchannel" is modelled with the following type:
+
+    bool multiset
+
+This expresses that replies from the Receiver are just one bit.
+
+Both Channels are instances of an abstract channel, that is modelled with
+the type 
+  
+    'a multiset.
+
+------------------------------------------------------------------------------
+
+The events.
+
+An `execution' of the system is modelled by a sequence of 
+
+    <system_state, action, system_state>
+
+transitions. The actions, or events, of the system are described by the
+following ML-style datatype declaration:
+
+    'm action = S_msg ('m)           (* Rqt for Sender to send mesg      *)
+              | R_msg ('m)           (* Mesg taken from Receiver's queue *)
+              | S_pkt_sr ('m packet) (* Packet arrives in Schannel       *)
+              | R_pkt_sr ('m packet) (* Packet leaves Schannel           *)
+              | S_pkt_rs (bool)      (* Packet arrives in Rchannel       *)
+              | R_pkt_rs (bool)      (* Packet leaves Rchannel           *)
+              | C_m_s                (* Change mode in Sender            *)
+              | C_m_r                (* Change mode in Receiver          *)
+              | C_r_s                (* Change round in Sender           *)
+              | C_r_r ('m)           (* Change round in Receiver         *)
+
+------------------------------------------------------------------------------
+
+The Specification.
+
+The abstract description of system behaviour is given by defining an
+IO/automaton named "Spec". The state of Spec is a message queue,
+modelled as an "'m list". The only actions performed in the abstract
+system are: "S_msg(m)" (putting message "m" at the end of the queue);
+and "R_msg(m)" (taking message "m" from the head of the queue).
+
+
+------------------------------------------------------------------------------
+
+The Verification.
+
+The verification proceeds by showing that a certain mapping ("hom") from
+the concrete system state to the abstract system state is a `weak
+possibilities map` from "Impl" to "Spec". 
+
+
+    hom : (S_state * Sch_state * R_state * Rch_state) -> queue
+
+The verification depends on several system invariants that relate the
+states of the 4 processes. These invariants must hold in all reachable
+states of the system. These invariants are difficult to make sense of;
+however, we attempt to give loose English paraphrases of them.
+
+Invariant 1.
+
+This expresses that no packets from the Receiver to the Sender are
+dropped by Rchannel. The analogous statement for Schannel is also true.
+
+    !b. R.replies b = S.received b + Rch b 
+    /\
+    !pkt. S.sent(hdr(pkt)) = R.received(hdr(b)) + Sch(pkt)
+
+
+Invariant 2.
+
+This expresses a complicated relationship about how many messages are
+sent and header bits.
+
+    R.header = S.header 
+    /\ S.mode = SENDING
+    /\ R.replies (flip S.header) <= S.sent (flip S.header)
+    /\ S.sent (flip S.header) <= R.replies header
+    OR
+    R.header = flip S.header
+    /\ R.mode = SENDING
+    /\ S.sent (flip S.header) <= R.replies S.header
+    /\ R.replies S.header <= S.sent S.header
+
+
+Invariant 3.
+
+The number of incoming messages in the Receiver plus the number of those
+messages in transit (in Schannel) is not greater than the number of
+replies, provided the message isn't current and the header bits agree.
+
+    let mesg = <S.header, m>
+    in
+    R.header = S.header
+    ==>
+    !m. (S.messages = [] \/ m ~= hd S.messages)
+        ==> R.received mesg + Sch mesg <= R.replies (flip S.header)
+
+
+Invariant 4.
+
+If the headers are opposite, then the Sender queue has a message in it.
+
+    R.header = flip S.header ==> S.messages ~= []
+
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/HOL/IOA/NTP/Receiver.ML	Thu Apr 13 16:57:18 1995 +0200
@@ -0,0 +1,30 @@
+(*  Title:      HOL/IOA/NTP/Receiver.ML
+    ID:         $Id$
+    Author:     Tobias Nipkow & Konrad Slind
+    Copyright   1994  TU Muenchen
+*)
+
+goal Receiver.thy
+ "S_msg(m) ~: actions(receiver_asig)      &   \
+\ R_msg(m) : actions(receiver_asig)       &   \
+\ S_pkt(pkt) ~: actions(receiver_asig) &   \
+\ R_pkt(pkt) : actions(receiver_asig)  &   \
+\ S_ack(b) : actions(receiver_asig)    &   \
+\ R_ack(b) ~: actions(receiver_asig)   &   \
+\ C_m_s ~: actions(receiver_asig)         &   \
+\ C_m_r : actions(receiver_asig)          &   \
+\ C_r_s ~: actions(receiver_asig)         &   \
+\ C_r_r(m) : actions(receiver_asig)";
+  by(simp_tac (action_ss addsimps 
+               (Receiver.receiver_asig_def :: actions_def :: 
+                asig_projections @ set_lemmas)) 1);
+qed "in_receiver_asig";
+
+val receiver_projections = 
+   [Receiver.rq_def,
+    Receiver.rsent_def,
+    Receiver.rrcvd_def,
+    Receiver.rbit_def,
+    Receiver.rsending_def];
+
+
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/HOL/IOA/NTP/Receiver.thy	Thu Apr 13 16:57:18 1995 +0200
@@ -0,0 +1,89 @@
+(*  Title:      HOL/IOA/NTP/Receiver.thy
+    ID:         $Id$
+    Author:     Tobias Nipkow & Konrad Slind
+    Copyright   1994  TU Muenchen
+
+The implementation: receiver
+*)
+
+Receiver = List + IOA + Action + Multiset +
+
+types 
+
+'m receiver_state
+= "'m list * bool multiset * 'm packet multiset * bool * bool"
+(* messages  #replies        #received            header mode *)
+
+consts
+
+  receiver_asig :: "'m action signature"
+  receiver_trans:: "('m action, 'm receiver_state)transition set"
+  receiver_ioa  :: "('m action, 'm receiver_state)ioa"
+  rq            :: "'m receiver_state => 'm list"
+  rsent         :: "'m receiver_state => bool multiset"
+  rrcvd         :: "'m receiver_state => 'm packet multiset"
+  rbit          :: "'m receiver_state => bool"
+  rsending      :: "'m receiver_state => bool"
+
+defs
+
+rq_def       "rq == fst"
+rsent_def    "rsent == fst o snd"
+rrcvd_def    "rrcvd == fst o snd o snd"
+rbit_def     "rbit == fst o snd o snd o snd"
+rsending_def "rsending == snd o snd o snd o snd"
+
+receiver_asig_def "receiver_asig ==            \
+\ (UN pkt. {R_pkt(pkt)},                       \
+\  (UN m. {R_msg(m)}) Un (UN b. {S_ack(b)}),   \
+\  insert C_m_r (UN m. {C_r_r(m)}))"
+
+receiver_trans_def "receiver_trans ==                                    \
+\ {tr. let s = fst(tr);                                                  \
+\          t = snd(snd(tr))                                              \
+\      in                                                                \
+\      case fst(snd(tr))                                                 \
+\      of                                                                \
+\      S_msg(m) => False |                                               \
+\      R_msg(m) => rq(s) = (m # rq(t))   &                               \
+\                  rsent(t)=rsent(s)     &                               \
+\                  rrcvd(t)=rrcvd(s)     &                               \
+\                  rbit(t)=rbit(s)       &                               \
+\                  rsending(t)=rsending(s) |                             \
+\      S_pkt(pkt) => False |                                          \
+\      R_pkt(pkt) => rq(t) = rq(s)                        &           \
+\                       rsent(t) = rsent(s)                  &           \
+\                       rrcvd(t) = addm (rrcvd s) pkt        &           \
+\                       rbit(t) = rbit(s)                    &           \
+\                       rsending(t) = rsending(s) |                      \
+\      S_ack(b) => b = rbit(s)                        &               \
+\                     rq(t) = rq(s)                      &               \
+\                     rsent(t) = addm (rsent s) (rbit s) &               \
+\                     rrcvd(t) = rrcvd(s)                &               \
+\                     rbit(t)=rbit(s)                    &               \
+\                     rsending(s)                        &               \
+\                     rsending(t) |                                      \
+\      R_ack(b) => False |                                               \
+\      C_m_s => False |                                                  \
+\ C_m_r => count (rsent s) (~rbit s) < countm (rrcvd s) (%y.hdr(y)=rbit(s)) & \
+\             rq(t) = rq(s)                        &                     \
+\             rsent(t)=rsent(s)                    &                     \
+\             rrcvd(t)=rrcvd(s)                    &                     \
+\             rbit(t)=rbit(s)                      &                     \
+\             rsending(s)                          &                     \
+\             ~rsending(t) |                                             \
+\    C_r_s => False |                                                    \
+\ C_r_r(m) => count (rsent s) (rbit s) <= countm (rrcvd s) (%y.hdr(y)=rbit(s)) & \
+\             count (rsent s) (~rbit s) < count (rrcvd s) (rbit(s),m) &  \
+\             rq(t) = rq(s)@[m]                         &                \
+\             rsent(t)=rsent(s)                         &                \
+\             rrcvd(t)=rrcvd(s)                         &                \
+\             rbit(t) = (~rbit(s))                      &                \
+\             ~rsending(s)                              &                \
+\             rsending(t)}"
+
+
+receiver_ioa_def "receiver_ioa == \
+\ (receiver_asig, {([],{|},{|},False,False)}, receiver_trans)"
+
+end
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/HOL/IOA/NTP/Sender.ML	Thu Apr 13 16:57:18 1995 +0200
@@ -0,0 +1,25 @@
+(*  Title:      HOL/IOA/NTP/Sender.ML
+    ID:         $Id$
+    Author:     Tobias Nipkow & Konrad Slind
+    Copyright   1994  TU Muenchen
+*)
+
+goal Sender.thy
+ "S_msg(m) : actions(sender_asig)       &   \
+\ R_msg(m) ~: actions(sender_asig)      &   \
+\ S_pkt(pkt) : actions(sender_asig)  &   \
+\ R_pkt(pkt) ~: actions(sender_asig) &   \
+\ S_ack(b) ~: actions(sender_asig)   &   \
+\ R_ack(b) : actions(sender_asig)    &   \
+\ C_m_s : actions(sender_asig)          &   \
+\ C_m_r ~: actions(sender_asig)         &   \
+\ C_r_s : actions(sender_asig)          &   \
+\ C_r_r(m) ~: actions(sender_asig)";
+by(simp_tac (action_ss addsimps 
+             (Sender.sender_asig_def :: actions_def :: 
+              asig_projections @ set_lemmas)) 1);
+qed "in_sender_asig";
+
+val sender_projections = 
+   [Sender.sq_def,Sender.ssent_def,Sender.srcvd_def,
+    Sender.sbit_def,Sender.ssending_def];
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/HOL/IOA/NTP/Sender.thy	Thu Apr 13 16:57:18 1995 +0200
@@ -0,0 +1,85 @@
+(*  Title:      HOL/IOA/NTP/Sender.thy
+    ID:         $Id$
+    Author:     Tobias Nipkow & Konrad Slind
+    Copyright   1994  TU Muenchen
+
+The implementation: sender
+*)
+
+Sender = IOA + Action + Multiset + List +
+
+types
+
+'m sender_state = "'m list * bool multiset * bool multiset * bool * bool"
+(*                messages   #sent           #received      header  mode *)
+
+consts
+
+sender_asig   :: "'m action signature"
+sender_trans  :: "('m action, 'm sender_state)transition set"
+sender_ioa    :: "('m action, 'm sender_state)ioa"
+sq            :: "'m sender_state => 'm list"
+ssent,srcvd   :: "'m sender_state => bool multiset"
+sbit          :: "'m sender_state => bool"
+ssending      :: "'m sender_state => bool"
+
+defs
+
+sq_def       "sq == fst"
+ssent_def    "ssent == fst o snd"
+srcvd_def    "srcvd == fst o snd o snd"
+sbit_def     "sbit == fst o snd o snd o snd"
+ssending_def "ssending == snd o snd o snd o snd"
+
+sender_asig_def
+  "sender_asig == ((UN m. {S_msg(m)}) Un (UN b. {R_ack(b)}),       \
+\                  UN pkt. {S_pkt(pkt)},                           \
+\                  {C_m_s,C_r_s})"
+
+sender_trans_def "sender_trans ==                                     \
+\ {tr. let s = fst(tr);                                               \
+\          t = snd(snd(tr))                                           \
+\      in case fst(snd(tr))                                           \
+\      of                                                             \
+\      S_msg(m) => sq(t)=sq(s)@[m]   &                                \
+\                  ssent(t)=ssent(s) &                                \
+\                  srcvd(t)=srcvd(s) &                                \
+\                  sbit(t)=sbit(s)   &                                \
+\                  ssending(t)=ssending(s) |                          \
+\      R_msg(m) => False |                                            \
+\      S_pkt(pkt) => hdr(pkt) = sbit(s)      &                        \
+\                       (? Q. sq(s) = (msg(pkt)#Q))  &                \
+\                       sq(t) = sq(s)           &                     \
+\                       ssent(t) = addm (ssent s) (sbit s) &          \
+\                       srcvd(t) = srcvd(s) &                         \
+\                       sbit(t) = sbit(s)   &                         \
+\                       ssending(s)         &                         \
+\                       ssending(t) |                                 \
+\    R_pkt(pkt) => False |                                            \
+\    S_ack(b)   => False |                                            \
+\      R_ack(b) => sq(t)=sq(s)                  &                     \
+\                     ssent(t)=ssent(s)            &                  \
+\                     srcvd(t) = addm (srcvd s) b  &                  \
+\                     sbit(t)=sbit(s)              &                  \
+\                     ssending(t)=ssending(s) |                       \
+\      C_m_s => count (ssent s) (~sbit s) < count (srcvd s) (~sbit s) & \
+\               sq(t)=sq(s)       &                                   \
+\               ssent(t)=ssent(s) &                                   \
+\               srcvd(t)=srcvd(s) &                                   \
+\               sbit(t)=sbit(s)   &                                   \
+\               ssending(s)       &                                   \
+\               ~ssending(t) |                                        \
+\      C_m_r => False |                                               \
+\      C_r_s => count (ssent s) (sbit s) <= count (srcvd s) (~sbit s) & \
+\               sq(t)=tl(sq(s))      &                                \
+\               ssent(t)=ssent(s)    &                                \
+\               srcvd(t)=srcvd(s)    &                                \
+\               sbit(t) = (~sbit(s)) &                                \
+\               ~ssending(s)         &                                \
+\               ssending(t) |                                         \
+\      C_r_r(m) => False}"
+
+sender_ioa_def "sender_ioa == \
+\ (sender_asig, {([],{|},{|},False,True)}, sender_trans)"
+
+end
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/HOL/IOA/NTP/Spec.thy	Thu Apr 13 16:57:18 1995 +0200
@@ -0,0 +1,42 @@
+(*  Title:      HOL/IOA/NTP/Spec.thy
+    ID:         $Id$
+    Author:     Tobias Nipkow & Konrad Slind
+    Copyright   1994  TU Muenchen
+
+The specification of reliable transmission
+*)
+
+Spec = List + IOA + Action +
+
+consts
+
+spec_sig   :: "'m action signature"
+spec_trans :: "('m action, 'm list)transition set"
+spec_ioa   :: "('m action, 'm list)ioa"
+
+defs
+
+sig_def "spec_sig == (UN m.{S_msg(m)}, \
+\                     UN m.{R_msg(m)}, \
+\                     {})"
+
+trans_def "spec_trans ==                           \
+\ {tr. let s = fst(tr);                            \
+\          t = snd(snd(tr))                        \
+\      in                                          \
+\      case fst(snd(tr))                           \
+\      of                                          \
+\      S_msg(m) => t = s@[m]  |                    \
+\      R_msg(m) => s = (m#t)  |                    \
+\      S_pkt(pkt) => False |                    \
+\      R_pkt(pkt) => False |                    \
+\      S_ack(b) => False |                      \
+\      R_ack(b) => False |                      \
+\      C_m_s => False |                            \
+\      C_m_r => False |                            \
+\      C_r_s => False |                            \
+\      C_r_r(m) => False}"
+
+ioa_def "spec_ioa == (spec_sig, {[]}, spec_trans)"
+
+end