just one dedicated execution per document version -- NB: non-monotonicity of cancel always requires fresh update;
explicit terminate_execution;
tuned source structure;
no_document use_thy "Setup";
use_thy "Introduction";
use_thy "Foundations";
use_thy "Refinement";
use_thy "Inductive_Predicate";
use_thy "Evaluation";
use_thy "Adaptation";
use_thy "Further";