Studies on non-prioritized multiple belief revision

• Ano de defesa: 2021
• Autor(a) principal: Resina, Fillipe Manoel Xavier
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: eng
• Instituição de defesa: Biblioteca Digitais de Teses e Dissertações da USP
• Palavras-chave em Português: Base de crenças; Belief base; Belief revision; Choice revision; Multiple revision; Non-prioritized revision; Revisão choice; Revisão de crenças; Revisão múltipla; Revisão não-priorizada; Revisão seletiva; Selective revision
• Link de acesso: https://www.teses.usp.br/teses/disponiveis/45/45134/tde-17122021-115606/

Belief Revision deals with the problem of how a rational agent should proceed in face of new information. In the AGM paradigm, the most used framework in Belief Revision, given a set of beliefs, there are three possible epistemic changes in relation to a new belief: expansion, contraction and revision. Among them, we are particularly interested in the latter. A revision occurs when an agent receives new information possibly inconsistent with its epistemic state and has to change it in order to accommodate the new belief in a consistent way. However, new information may come as a set of beliefs (instead of a single one), a problem known as Multiple Revision, in which, unlike Iterated Revision, all new pieces of information are processed simultaneously. This thesis starts with a survey on the topic of Multiple Revision. The purpose is to bring and organize the state-of-the-art of the area, showing the different approaches developed since 1988 and the open problems that still exist. After that, different contributions on non-prioritized multiple revision are proposed. One of AGM revision\'s main properties is success, which guarantees that new information is always accepted by a rational agent, even when it has to give up a reasonable belief previously held. However, in more realistic scenarios, when dealing with a new belief that contradicts previous ones, an agent has the option to reject it, an approach called non-prioritized revision. Among the possible operations for this approach, Choice Revision is the one that deals with the case in which it is enough for the agent to absorb only a subset of the input set. We propose an axiomatic characterization of Choice Multiple Revision through two different constructions: one based on remainder sets and the other on kernel sets, along with algorithms for both of them. The approach was developed for belief bases and is not restricted to classical propositional logic. Still about the possible operations for non-prioritized multiple revision and the option the agent has to accept or reject a new information, Selective Revision came up as a third possibility, allowing the agent to accept only a part of the new belief. The operation was initially defined for single sentences as inputs and for belief sets. This thesis proposes a generalization of Selective Revision to the multiple case for both belief sets (theories) and belief bases. We provide constructions, postulates and representation theorems for different classes of Multiple Selective Revision.