just one dedicated execution per document version -- NB: non-monotonicity of cancel always requires fresh update;
explicit terminate_execution;
tuned source structure;
(*
To update:
cp /home/lcp/isabelle/Repos/HOL/Auth/{Message.thy,Message_lemmas.ML,Event.thy,Event_lemmas.ML,Public.thy,Public_lemmas.ML,NS_Public.thy} .
*)
use_thy "NS_Public";