Modelos de revisão de bases de crenças para fusão de ontologias

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Publications

Iterated belief change: the case of expansion into inconsistency

Publication . Fermé, Eduardo; Wassermann, Renata

Constructing models that allow iterated changes is one of the most studied problems in the literature on belief change. However, up to now, iteration of expansion was only studied as a special case of consistent revision and, as far we know, there is no work in the literature that deals with expansions into inconsistency in a supraclassical framework. In this paper, we provide a semantics for iterated expansion, as well as its axiomatic characterization. We extend the model to two well-known families of iterated belief change (natural and lexicographic). Iteration of expansion can be combined with existent models of iteration of revision and contraction. Since we are able to accommodate different inconsistent belief states, iteration of expansion allows us to define new belief change functions that are currently only defined for belief bases: semi revision, external revision, as well as consolidation.

2017Conference object

Open access

Domain-specific trust for context-aware BDI Agents: preliminary work

Publication . Casals, Arthur; Fermé, Eduardo; Brandao, Anarosa A. F.

Context-aware systems are capable of perceiving the physical environment where they are deployed and adapt their behavior accordingly. Multiagent systems based on the BDI architecture can be used to process contextual information in the form of beliefs. Contextual information can be divided and structured in the form of information domains. Information and experience sharing enables a single agent to receive data on different information domains from another agent. In this scenario, establishing a trust model between agents can take into account the relative perceptions each agent has of the others, as well as different trust degrees for different information domains. The objective of this work is to adapt an epistemic model to be used by agents with their belief revision in order to establish a mechanism of domain-specific relative trust attribution. Such mechanism will allow for each agent to possess different trust degrees associated with other agents regarding different information domains.

2018Conference object

Open access

On ensconcement and contraction

Publication . Fermé, Eduardo; Garapa, Marco; Reis, Maurício

In this article we present an axiomatic characterization for the ensconcement-based contractions. We study the interrelation among ensconcement-based contractions and brutal contractions, and we present two ways of defining an ensconcement relation by means of a base contraction operation. Finally, we study the interrelations among ensconcement-based contraction and epistemic entrenchment-based contractions and among brutal contractions and severe withdrawals.

2017Journal article

Open access

Shielded base contraction

Publication . Garapa, Marco; Fermé, Eduardo; Reis, Maurício D. L.

The one that is considered the standard model in the area of logic of belief change was proposed by Alchourrón, Gärdenfors and Makinson in 1985 and is, nowadays, known as the AGM model. Two of the main shortcomings pointed out to the AGM model of belief change are the (impractical) use of belief sets to represent belief states and the (unrealistic) acceptance of any new information. In this paper we study a kind of operators—known as shielded base contractions—which address both those issues. Indeed, on the one hand, these operators are defined on belief bases (rather than belief sets) and, on the other hand, they are constructed with the underlying idea that not all new informations are accepted. We propose twenty different classes of shielded base contractions and obtain axiomatic characterizations for each of them. Additionally we thoroughly investigate the interrelations (in the sense of inclusion) among all those classes. More precisely, we analyse whether each of those classes is or is not (strictly) contained in each of the remaining ones.

2018Journal article

Open access

On the logic of theory change: iteration of expansion

Publication . Fermé, Eduardo; Wassermann, Renata

Constructing models that allow for iterated changes is one of the most studied problems in the literature on belief change. However, up to now, iteration of expansion was only studied as a special case of consistent revision and, as far we know, there is no work in the literature that deals with expansions into inconsistency in a supraclassical framework. In this paper, we provide a semantics for iterated expansion, as well as its axiomatic characterization. We extend the model to two well-known families of iterated belief change (natural and lexicographic). Iteration of expansion can be combined with existent models of iteration of revision and contraction. Since we are able to accommodate different inconsistent belief states, iteration of expansion allows us to define new belief change functions that are currently only defined for belief bases: semi-revision, external revision, as well as consolidation.

2018Journal article

Open access