static Collection<S> ai_applyFactToFactRules() {
  L<IfThen> rules = map nlLogic_parseRule(splitAtEmptyLines(mL_raw("Fact-to-fact rules")));
  Set<S> outFacts = ai_deriveFacts(rules, mL("Random facts"));
  appendToMechList("Derived facts", outFacts);
  ret outFacts;
}