 It is also possible to add valuation-changing substitutions (i.e., “factual changes”) to plausibility action models. This is done exactly as it is done for action models proper: substitutions are added to plausibility action models, the action-priority update is modified to account for substitutions in the semantics, and the first reduction axiom is changed to account for substitutions in the axiomatics. See  Appendix G  for details. 