Circumscription

Commonsense Law of Inertia

• Inertia is normal. Change is exceptional.
  

  Normally, nothing happens

• Circumscription used to minimize the extension of
  initiates, terminates, releases, happens

Circumscription

• Circumscription of a first-order formula may be second order
• For many cases circumscription reduces to predicate completion
• Predicate completion is used here, e.g.,
  

  ∀ E,F,T (terminates(E,F,T) ⇔
  ((E = tapOff & F = filling) | (E = overflow & F = filling)))