AI 2008: Advances in Artificial Intelligence

Volume 5360 of the series Lecture Notes in Computer Science pp 18-29

Introspective Forgetting

  • Hans van DitmarschAffiliated withComputer Science, University of OtagoIRIT, Université Paul Sabatier
  • , Andreas HerzigAffiliated withIRIT, Université Paul Sabatier
  • , Jérôme LangAffiliated withIRIT, Université Paul Sabatier
  • , Pierre MarquisAffiliated withCRIL, Université d’Artois


We model the forgetting of propositional variables in a modal logical context where agents become ignorant and are aware of each others’ or their own resulting ignorance. The resulting logic is sound and complete. It can be compared to variable-forgetting as abstraction from information, wherein agents become unaware of certain variables: by employing elementary results for bisimulation, it follows that beliefs not involving the forgotten atom(s) remain true.


modal logic forgetting abstraction action logic belief change