Abhaya C. Nayak

Iterated belief change based on epistemic entrenchment

In this paper it is argued that, in order to solve the problem of iterated belief change, both the belief state and its input should be represented as epistemic entrenchment (EE) relations. A belief revision operation is constructed that updates a given EE relation to a new one in light of an evidential EE relation. It is shown that the operation in question satisfies generalized versions of the Gärdenfors revision postulates. The account offered is motivated by Spohns ordinal conditionalization functions, and can be seen as the Jeffrization of a proposal considered by Rott.

Dynamic belief revision operators

The AGM approach to belief change is not geared to provide a decent account of iterated belief change. Darwiche and Pearl have sought to extend the AGM proposal in an interesting way to deal with this problem. We show that the original Darwiche-Pearl approach is, on the one hand excessively strong and, on the other rather limited in scope. The later Darwiche-Pearl approach, we argue, although it addresses the first problem, still remains rather permissive. We address both these issues by (1) assuming a dynamic revision operator that changes to a new revision operator after each instance of belief change, and (2) strengthening the Darwiche-Pearl proposal. Moreover, we provide constructions of this dynamic revision operator via entrenchment kinematics as well as a simple form of lexicographic revision, and prove representation results connecting these accounts.

Foundational belief change

This paper is concerned with the construction of a base contraction (revision) operation such that the theory contraction (revision) operation generated by it will be fully AGM-rational. It is shown that the theory contraction operation generated by Fuhrmannsminimal base contraction operation, even under quite strong restrictions, fails to satisfy the “supplementary postulates” of belief contraction. Finally Fuhrmanns construction is appropriately modified so as to yield the desired properties. The new construction may be described as involving a modification of safe (base) contraction so as to make it maxichoice.

Approaches for semantic interoperability between domain ontologies

: Domain ontologies and knowledge-based systems have become very important in the agent and semantic web communities. As their use has increased, providing means of resolving semantic differences has also become very important. In this paper we survey the approaches that have been proposed for providing interoperability among domain ontologies. We also discuss some key issues that still need to be addressed if we are to move from semi-automated to fully automated approaches to providing consensus among heterogeneous ontologies.

Belief change as change in epistemic entrenchment

In this paper, it is argued that both the belief state and its input should be represented as epistemic entrenchment (EE) relations. A belief revision operation is constructed that updates a given EE relation to a new one in light of an evidential EE relation, and an axiomatic characterization of this operation is given. Unlike most belief revision operations, the one developed here can handle both “multiple belief revision” and “iterated belief revision”.

Taking Levi identity seriously: a plea for iterated belief contraction

Most work on iterated belief change has focused on iterated belief revision, namely how to compute (K

Forgetting and knowledge update

^{\rm *}_{x}

Theories of intentions in the framework of situation calculus

)

Measuring similarity in belief revision

^{\rm *}_{y}

Biomarker information extraction tool (BIET) development using natural language processing and machine learning

. Historically however, belief revision can be defined in terms of belief expansion and belief contraction, where expansion and contraction are viewed as primary operators. Accordingly, our attention to iterated belief change should be focused on constructions like (K