Reference:
Tomi Janhunen. Weakened negative introspection in autoepistemic reasoning. Research Report A21, Helsinki University of Technology, Digital Systems Laboratory, Espoo, Finland, February 1993.
Abstract:
A new weakened scheme for negative introspection in autoepistemic reasoning is proposed. The scheme is formulated prooftheoretically in terms of enumerations of formulae. The resulting sets of conclusions based on this negative introspection principle, cautious autoepistemic expansions, generalize Moore style stable expansions such that every set of premises has a cautious expansion. A finitary characterization is developed for cautious expansions. The elimination of weakly grounded cautious expansions yields a subclass of cautious expansions: the Ngrounded cautious expansions. The least Ngrounded cautious expansion is shown to be unique and the intersection of all Ngrounded cautious expansions. This is in contrast with Moore style stable expansions. The least Ngrounded cautious expansion can be constructed iteratively as the least fixed point of a monotonic operator. Such a construction is exceptional, since autoepistemic expansions are nonconstructive in general. It is also shown that cautious autoepistemic logic is decidable. A comparison is made with some other schemes of weakened negative introspection. The given set of examples demonstrates that the proposed negative introspection principle is stronger than, e.g., that of the wellfounded semantics.
Keywords:
autoepistemic logic, nonmonotonic reasoning, weakened negative introspection
Suggested BibTeX entry:
@techreport{HUTTCSA21,
address = {Espoo, Finland},
author = {Tomi Janhunen},
institution = {Helsinki University of Technology, Digital Systems Laboratory},
month = {February},
number = {A21},
pages = {82},
title = {Weakened Negative Introspection in Autoepistemic Reasoning},
type = {Research Report},
year = {1993},
}
