Repository logo
 
Publication

Advances on belief base dynamics

2017-11-20Doctoral thesis Open access
Simple item page
datacite.subject.fosCiências Naturais::Matemáticaspt_PT
datacite.subject.fosEngenharia e Tecnologia::Engenharia Eletrotécnica, Eletrónica e Informáticapt_PT
dc.contributor.advisorFermé, Eduardo Leopoldo
dc.contributor.advisorReis, Maurício Duarte Luís
dc.contributor.authorGarapa, Marco Paulo Ferreirinha
dc.date.accessioned2018-02-08T15:59:24Z
dc.date.available2018-02-08T15:59:24Z
dc.date.issued2017-11-20
dc.description.abstractThe main goal underlying the research area of belief change consists in finding appropriate ways of modelling the belief state of a rational agent and, additionally, the changes which occur in such a state when the agent receives new information. The most important model of belief change is the so-called AGM model, proposed in [AGM85]. In this model, the belief state of an agent is represented by a belief set—a deductively closed set of sentences. A change consists in adding or removing a specific sentence from a belief set to obtain a new belief set. Two of the main shortcomings pointed out to the AGM model of belief change are the use of belief sets to represent belief states and the (unrealistic) acceptance of any new piece of information. In this thesis we address both those issues. We present axiomatic characterizations for ensconcement-based contractions and for brutal contractions, two kinds of belief bases contraction operators introduced in [Wil94b] that are based on the concept of ensconcement, which is a generalization to the case of belief bases of the concept of epistemic entrenchment introduced in [Ga¨r88, GM88]. We compare the axiomatic characterizations of these operators with those of other well-known base contraction operators and study the interrelations among the former and the contraction operators based on epistemic entrenchments. We study non-prioritized base change operators, namely shielded base contractions and credibility-limited base revisions. We propose several different classes of shielded base contractions and obtain axiomatic characterizations for each one of them. Additionally we thoroughly investigate the interrelations (in the sense of inclusion) among all those classes. Afterwards we perform a similar study for credibility-limited base revisions. Finally, we study the interrelation between the different proposed classes of operators of credibility-limited base revision and of shielded contraction by means of the consistency-preserving Levi identity and the Harper identity.pt_PT
dc.description.abstractO objetivo principal da a´rea de revis˜ao de cren¸cas ´e encontrar modelos que permitam modelar o estado de cren¸cas de um agente racional, bem como as mudan¸cas que ocorrem nesse estado de cren¸cas quando o agente recebe novas informa¸co˜es. O modelo mais influente desta ´area ´e o chamado modelo AGM proposto em [AGM85]. Neste modelo, o estado de cren¸cas de um agente ´e representado por um conjunto de cren¸cas—conjunto de f´ormulas dedutivamente fechado. Uma mudan¸ca consiste em adicionar ou remover uma fo´rmula espec´ıfica de um conjunto de cren¸cas para obter um novo conjunto de crenc¸as. Dois dos principais problemas apontados ao modelo AGM sa˜o o uso de conjuntos de cren¸cas para representar estados de cren¸ca e a aceita¸ca˜o (irrealista) de qualquer nova informa¸ca˜o. Nesta tese abordamos ambas as quest˜oes. Apresentamos caracteriza¸co˜es axiom´aticas para contra¸c˜oes baseadas em ensconcements e para contra¸c˜oes brutais, dois tipos de operadores de contrac¸˜ao em bases de cren¸cas introduzidos em [Wil94b] e que se baseiam no conceito de ensconcement— generaliza¸ca˜o em bases de cren¸cas, do conceito de epistemic entrenchment introduzido em [Ga¨r88, GM88]. Comparamos as caracteriza¸c˜oes axiom´aticas destes operadores com as de outros operadores de contrac¸˜ao em bases bem conhecidos e estudamos as inter-rela¸co˜es entre os primeiros e os operadores de contra¸ca˜o baseados em epistemic entrenchments. Estudamos operadores de mudanc¸as de crenc¸as na˜o-priorizados em bases, nomeadamente contra¸c˜oes protegidas e revis˜oes com limite de credibilidade. Propomos v´arias classes de operadores de contra¸c˜oes protegidas e obtemos teoremas de representa¸ca˜o para cada uma dessas classes. Investigamos, igualmente, as inter-rela¸co˜es (no sentido de inclusa˜o) entre todas essas classes. Posteriormente, realizamos um estudo semelhante para reviso˜es com limite de credibilidade. Finalmente, estudamos a inter-relac¸˜ao entre as diferentes classes propostas de operadores (definidos em bases de cren¸cas) de revis˜ao com limite de credibilidade e de contra¸co˜es protegidas atrav´es da identidade de Levi conservadora-da-consistˆencia e da identidade de Harper.pt_PT
dc.identifier.tid101561016pt_PT
dc.identifier.urihttp://hdl.handle.net/10400.13/1797
dc.language.isoengpt_PT
dc.relationResearch Centre for Mathematics and Applications
dc.subjectBelief changept_PT
dc.subjectBelief basespt_PT
dc.subjectEnsconcementpt_PT
dc.subjectEnsconcement-based contractionspt_PT
dc.subjectShielded contractionpt_PT
dc.subjectCredibility-limited revisionpt_PT
dc.subjectMudanças de crençaspt_PT
dc.subjectBases de crençaspt_PT
dc.subjectContrações baseadas em Ensconcementspt_PT
dc.subjectContração protegidapt_PT
dc.subjectRevisão com limite de credibilidadept_PT
dc.subjectMathematics, specialty of Logic and Computer Sciencept_PT
dc.subject.pt_PT
dc.subjectFaculdade de Ciências Exatas e da Engenhariapt_PT
dc.titleAdvances on belief base dynamicspt_PT
dc.typedoctoral thesis
dspace.entity.typePublication
oaire.awardTitleResearch Centre for Mathematics and Applications
oaire.awardURIinfo:eu-repo/grantAgreement/FCT/6817 - DCRRNI ID/UID%2FMAT%2F04674%2F2013/PT
oaire.fundingStream6817 - DCRRNI ID
person.familyNameGarapa
person.givenNameMarco
person.identifier.ciencia-id2712-ABAA-7FAD
person.identifier.orcid0000-0003-3697-1565
person.identifier.scopus-author-id57191524100
project.funder.identifierhttp://doi.org/10.13039/501100001871
project.funder.nameFundação para a Ciência e a Tecnologia
rcaap.rightsopenAccesspt_PT
rcaap.typedoctoralThesispt_PT
relation.isAuthorOfPublication17ad4b81-ed14-4f2c-9302-0c6fa9125673
relation.isAuthorOfPublication.latestForDiscovery17ad4b81-ed14-4f2c-9302-0c6fa9125673
relation.isProjectOfPublicationd5b6b03a-3dfd-4fb2-97c0-ead0a1c55f24
relation.isProjectOfPublication.latestForDiscoveryd5b6b03a-3dfd-4fb2-97c0-ead0a1c55f24
thesis.degree.nameDoctorate in Mathematics, specialty of Logic and Computer Sciencept_PT

Files

Original bundle
Now showing 1 - 1 of 1
Thumbnail Image
Name:
DoutoramentoMarcoGarapa.pdf
Size:
1.65 MB
Format:
Adobe Portable Document Format
Download
License bundle
Now showing 1 - 1 of 1
No Thumbnail Available
Name:
license.txt
Size:
1.71 KB
Format:
Item-specific license agreed upon to submission
Description:
Download

Collections

Teses de Doutoramento