APPROXIMATE EXTENSIONS IN DEFAULT LOGIC
Yihua Shi, Setsuo Arikawa · Bulletin of informatics and cybernetics · 1992
The extension, one of the most important notions in Reiter's default logic, is not computable in general. This paper proposes new notions of sub-extension and approximate extension which can successively be constructed from a given default theory. By introducing a time-bound into them, we show that every step of our construction terminates in a finite time. We also prove that the set of approximate extensions contains the set of extensions in Reiter's sense.