diff -r 92de80b43d28 -r 0c36c6a52a1d src/HOL/IOA/ABP/Env.thy
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/HOL/IOA/ABP/Env.thy	Thu Apr 13 16:55:14 1995 +0200
@@ -0,0 +1,47 @@
+(*  Title:      HOL/IOA/ABP/Impl.thy
+    ID:         $Id$
+    Author:     Tobias Nipkow & Konrad Slind
+    Copyright   1994  TU Muenchen
+
+The environment
+*)
+
+Env = IOA + Action +
+
+types
+
+'m env_state = "bool"
+(*              give next bit to system  *)
+
+consts
+
+env_asig   :: "'m action signature"
+env_trans  :: "('m action, 'm env_state)transition set"
+env_ioa    :: "('m action, 'm env_state)ioa"
+next       :: "'m env_state => bool"
+
+defs
+
+env_asig_def
+  "env_asig == ({Next},                 \
+\               UN m. {S_msg(m)},       \
+\               {})"
+
+env_trans_def "env_trans ==                                           \
+\ {tr. let s = fst(tr);                                               \
+\          t = snd(snd(tr))                                           \
+\      in case fst(snd(tr))                                           \
+\      of                                                             \
+\      Next       => t=True |                                         \
+\      S_msg(m)   => s=True & t=False |                               \
+\      R_msg(m)   => False |                                          \
+\      S_pkt(pkt) => False |                                          \
+\      R_pkt(pkt) => False |                                          \
+\      S_ack(b)   => False |                                          \
+\      R_ack(b)   => False}"
+
+env_ioa_def "env_ioa == \
+\ (env_asig, {True}, env_trans)"
+
+end
+