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- Credibility-limited base revision: new classes and their characterizationsPublication . Garapa, Marco; Fermé, Eduardo; Reis, MaurícioIn this paper we study a kind of operator —known as credibility-limited base revisions— which addresses two of the main issues that have been pointed out to the AGM model of belief change. 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 information is accepted. We propose twenty different classes of credibility limited base revision operators 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 one of those classes is or is not (strictly) contained in each of the remaining ones.
- Levi and Harper identities for non-prioritized belief base changePublication . Garapa, Marco; Fermé, Eduardo; Reis, Maurício D. L.In this paper, we investigate the relation between shielded base contraction postulates and credibility-limited (CL) base revision postulates. More precisely, we identify (i) the relation between the postulates satisfied by a shielded base contraction operator and the postulates satisfied by the CL base revision operator that is defined from it by means of the consistency-preserving Levi identity and (ii) the relation between the postulates satisfied by a CL base revision operator and the postulates satisfied by the shielded base contraction operator that is defined from it by means of the Harper identity. Furthermore, we show that the consistency-preserving Levi identity and the Harper identity establish a one-to one correspondence between the twenty classes of shielded base contractions presented in [21] and the twenty classes of credibility-limited base revisions presented in [22].
- Choosing What to Believe - New Results in Selective RevisionPublication . Resina, Fillipe; Garapa, Marco; Wassermann, Renata; Fermé, Eduardo; Reis, MaurícioSelective Revision was proposed by Ferme and Hansson as ´ a belief revision operation in which it is possible to accept only a part of the input information. In this paper, we extend Selective Revision to belief bases and also to logics not closed under negation.
- Relevance, recovery and recuperation: a prelude to ring withdrawalPublication . Fermé, Eduardo; Garapa, Marco; Abhaya Nayak; Reis, Maurício D. L.; Reis, MaurícioIn this paper, we introduce recuperative withdrawals, belief change operators that satisfy recuperation, a postulate weaker than recovery, all the AGM postulates for contraction except recovery and another postulate which is a slightly stronger condition than conjunctive inclusion. Furthermore, we present a constructive definition for a class of operators —named ring withdrawals— which are such that the outcome of a ring withdrawal of a belief set 𝐊 by a sentence 𝛼 is obtained by adding to the set of most plausible models ‖𝐊‖ all the worlds which are as close to ‖𝐊‖ as its closest ¬𝛼-worlds. Ring withdrawals satisfy the Lindström and Rabinowicz’s interpolation thesis. We show that the classes of recuperative withdrawals and of ring withdrawals are identical. Additionally we show that the class of ring withdrawals is not contained in and does not contain the class of AGM contractions or the class of severe withdrawals. Finally we present methods for defining an operator of ring withdrawal by means of a severe withdrawal operator and by means of an AGM contraction operator, and vice-versa.
- Knowledge-driven profile dynamicsPublication . Fermé, Eduardo; Garapa, Marco; Reis, Maurício D. L.; Almeida, Yuri; Paulino, Teresa; Mariana Rodrigues; Garapa, Marco; Aristides da Silva Godinho de Almeida, Yuri; Fermé, Eduardo; Reis, Maurício; Paulino, TeresaIn the last decades, user profiles have been used in several areas of information technology. In the literature, most research works, and systems focus on the creation of profiles (using Data Mining techniques based on user’s navigation or interaction history). In general, the dynamics of profiles are made by means of a systematic recreation of the profiles, without using the previous profiles. In this paper we propose to formalize the creation, representation, and dynamics of profiles from a Knowledge-Driven perspective. We introduce and axiomatically characterize four operators for changing profiles using a belief change inspired approach.