static Collection<S> nlLogic_unresolvedFactsToQuestions(RuleFailInfo ruleFail) {
  if (ruleFail == null) ret emptyList();
  Exp e = nlLogic_applyMatches(nlLogic_firstCondition(ruleFail.remainingConditions), ruleFail.matches);
  // Now have: fact(bla) in e
  
  if (e cast Func)
    if (eq(e.name, 'fact)) {
      S fact = "Unresolved fact: " + e.arg.text();
      Pair<L<IfThen>, LS> p = ai_activeRulesAndFacts(ll(fact));
      ret ai_deriveOutput(p.a, p.b);
    }
    
  ret emptyList();
}