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Topic: Belief revision


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In the News (Sun 15 Nov 09)

  
  Belief Revision in Multi-agent Systems
In the first case the belief revision problem is approached from a centralized perspective, that is, it is assigned to a single agent; whereas, in the second case, it is approached from a distributed perspective, that is, it is assigned to a group of agents.
To make practical and useful belief revision in a multi-agent environment, we substitute the priority of the incoming information with the principle of recoverability: any previously believed information item must belong to the current cognitive state if it is consistent with it.
Therefore, an alternative approach is the distributed one, where the belief revision process is no longer assigned to a single agent but to a society of agents, in which each single is able to perform belief revision and communicate with the others.
dit.unitn.it /~pgiorgio/thesis.html   (1149 words)

  
 Workshop on Belief Revision- ILLC 2004
Belief revision theory was first developed to give a formal answer to this question, following a long tradition of philosophical work on theory change.
Normative theories of belief revision advocated by philosophers and logicians (who study the question as to how people should change their minds) have been paralleled by more descriptive approaches taken by cognitive psychologists and social scientists (who want to know how people in fact do so).
Belief revision is perhaps the most fundamental of our cognitive skills: therefore, its formal understanding cannot abstract from empirical data on belief change in humans.
www.unisi.it /ricerca/dip/fil_sc_soc/dot-sc/belrev.html   (576 words)

  
 Belief Revision Reasoning Non-monotonic inference
The study and results are presented in the context of certain logic-based formalizations of belief revision, syntactic and model-theoretic representations of belief states, and performance models of human deduction.
A belief revision task was given to people, in which these conditionals were used to define "initial belief" sentences, which were then followed by a "new information" sentence that created an inconsistency with the initial set of beliefs.
For normative belief revision models, such findings call into question the notion that conditionals ought to be more entrenched by virtue of their syntactic form.
www.cs.ualberta.ca /~ree/research/cogsci.belrev.pubs.html   (1562 words)

  
 Belief revision
Revising nonmonotonic belief sets: The case of defeasible logic.
We define revision and contraction operators, propose postulates motivated by the form or the intuition of the AGM postulates for classical belief revision, and verify that the operators satisfy the postulates.
Abstract:We present three approaches to revision of belief bases, which are also examined in the case in which the sentences in the base are partitioned between those which can and those which cannot be changed; the approaches are shown to be semantically equivalent.
www.itee.uq.edu.au /~guido/Papers/brevision.html   (578 words)

  
 ESSLLI 2005 - Workshop: Belief revision and dynamic logic   (Site not responding. Last check: 2007-11-05)
In 'standard' AGM belief revision, a deductively closed theory T is revised with a formula phi, resulting in a revised theory T * phi.
In this setting a pointed Kripke model for belief in the theory T satisfies in particular B ~phi, and a dynamic modal operator [* phi], for 'belief revision with phi', is interpreted as an epistemic state transformer [[* phi]].
Such dynamic (and generally epistemic) approaches allow in a natural fashion for multi-agent belief revision, for belief revision wi th epistemic beliefs (typically: of other agents), and provide refreshing insights on irrevocable belief revision and iterated belief revision.
www.macs.hw.ac.uk /esslli05/giveabs.php?47   (246 words)

  
 Theses from Uppsala University : 540 - Non-linear belief revision
Three structures for belief revision: plausability relations on states, relations of epistemic entrenchment on propositions and systems of spheres (hypertheories), are generalised to the non-linear (non-connected) case.
A formal language with dynamic and doxastic (belief) modal operators (DDL) is used to establish interdefinability properties between the structures and complete axiomatisations are given.
The ideas and results of Darwiche and Pearl (1997) for iterated belief revision on linear structures are generalised to the non-linear case and axiomatisations in DDL are given.
publications.uu.se /theses/abstract.xsql?lang=en&isbn=91-554-4866-6   (267 words)

  
 Belief Revision - Cambridge University Press   (Site not responding. Last check: 2007-11-05)
Belief revision is a topic of much interest in theoretical computer science and logic, and it forms a central problem in research into artificial intelligence.
This book contains a collection of research articles on belief revision that are completely up to date and an introductory chapter that presents a survey of current research in the area and the fundamentals of the theory.
Belief revision and a theory of communication; 5.
www.cup.cam.ac.uk /catalogue/catalogue.asp?ISBN=0521545641   (225 words)

  
 Constraint programming, belief revision, and combinatorial optimization
Belief revision is generally concerned with the formalization of the principles behind changing collections of formal theories.
The underlying computational mechanisms required for belief revision are exactly those developed for so-called "over constrained" optimization problems.
Finally, the area of belief revision has concentrated on the formal properties of logical theory change and update, in order to define sensible properties of accumulating beliefs.
www.pims.math.ca /birs/workshops/2003/03w5105   (537 words)

  
 Belief revision - Computing Reference - eLook.org
A fundamental issue in belief revision is how to decide what information to retract in order to maintain consistency, when the addition of a new belief to a theory would make it inconsistent.
Usually, an ordering on the sentences of the theory is used to determine priorities among sentences, so that those with lower priority can be retracted.
The postulates of the AGM Theory for Belief Revision describe minimal properties a revision process should have.
www.elook.org /computing/belief-revision.htm   (107 words)

  
 IngentaConnect Belief Revision And Epistemology   (Site not responding. Last check: 2007-11-05)
Postulational approaches attempt to understand the dynamics of belief revision by appealing to no more than the set of beliefs held by an agent and the logical relations between them.
A proper account of belief revision must also appeal to the arguments supporting beliefs, and recognize that those arguments can be defeasible.
Belief revision is better studied from within an independently motivated epistemological theory.
www.ingentaconnect.com /content/klu/synt/2000/00000122/F0020001/00242119   (196 words)

  
 Welcome to Belief Revision!
We all know that beliefs can sometimes be wrong, so intelligent agents need to be able to revise beliefs when they acquire new information that contradicts their old beliefs.
Belief Revision capabilities are crucially important for sound decision making and effective communication.
In fact, belief revision is fundamental to an intelligent agent's being!
www.beliefrevision.org /index.jsp   (98 words)

  
 Distributed Belief Revision Test Bed   (Site not responding. Last check: 2007-11-05)
The Distributed Belief Revision Tested - DiBeRT is intended to study and model inherently distributed systems, with decentralised control, in which the available information is incomplete and dynamic, and where the time factor is relevant.
The decision of how and when to use external beliefs in an agent's knowledge base is fundamental to the characterisation of a distributed belief revision system.
Local evaluation of the shared propositions - the local beliefs prevail over the communicated beliefs, i.e., the use of an external belief is conditioned by the existence or absence of the belief in the agent's local knowledge base.
paginas.fe.up.pt /~mbnm/DiBeRT.html   (648 words)

  
 History of Twentieth-Century Philosophy of Science Book 8
A belief is any unit of language that may be true or false, and that is accepted as true for any reason including notably reasons acceptable in science.
Since beliefs can function as partial definitions, they are both empirical and analytical statements that enable analysis of the composition in the concept or meaning associated with a descriptive term.
Beliefs thereby reveal the meaning components defined in terms of a theory that make the meaning theory-laden due to the context supplied by the theory.
philsci.com /book8.htm   (3055 words)

  
 Belief Revision: A Critique   (Site not responding. Last check: 2007-11-05)
The problem of belief change---how an agent should revise her beliefs upon learning new information---has been an active area of research in both philosophy and artificial intelligence.
The main message is that to study belief change carefully, we must be quite explicit about the ``ontology'' or scenario underlying the belief change process.
In the latter case, how firm is the belief?) For example, we argue that even postulates that have been called ``beyond controversy'' are unreasonable when the agent's beliefs include beliefs about her own epistemic state as well as the external world.
ai.stanford.edu /people/nir/Abstracts/FrH8.html   (261 words)

  
 Belief Revision and Genetic Algorithms   (Site not responding. Last check: 2007-11-05)
Belief revision is the process of determining the most probable state of each of the random variables.
A global search algorithm such as genetic algorithms can be adapted to perform belief revision.
GALGO[5] used GAs to perform belief revision over Bayesian Networks; we use a similar approach to perform belief revision over BKBs.
www.cs.indiana.edu /event/maics96/Proceedings/Borghetti/node3.html   (709 words)

  
 Belief Revision with Unreliable Observations   (Site not responding. Last check: 2007-11-05)
Research in belief revision has been dominated by work that lies firmly within the classic AGM paradigm, characterized by a well-known set of postulates governing the behavior of ``rational'' revision functions.
A postulate that is rarely criticized is the success postulate: the result of revising by an observed proposition $\vphi$ results in belief in $\vphi$.
We propose a semantics that captures a new ontology for studying revision functions, which can handle noisy observations in a natural way, while retaining the classical AGM model as a special case.
www.eecs.harvard.edu /~nir/Abstracts/BFH1.html   (145 words)

  
 Belief Revision via Lamarckian Evolution   (Site not responding. Last check: 2007-11-05)
We present a system for performing belief revision in a multi-agent environment.
The system is called GBR (Genetic Belief Revisor) and it is based on a genetic algorithm.
The operator is implemented by means of a belief revision procedure that, by tracing logical derivations, identifies the memes leading to contradiction.
www.cs.bris.ac.uk /~ILPnet2/Tools/Reports/Abstracts/ngc-lamrigper-2003.html   (264 words)

  
 Belief Revision in a Multi-Agent Environment   (Site not responding. Last check: 2007-11-05)
In this project we are working on a model for belief revision integrating symbolic and numerical methods to be embodied in an agent's architecture acting in a multi-agent domain in which it is needed to assess the credibility of information coming from different sources.
Pieces of knowledge may not only be abandoned ("non-monotonicity" of belief revision") but also rescued ("recoverability" of belief revision") after a new coming information.
Furthermore, the splitting between the symbolic treatment of the inconsistencies and the numerical revision of the credibility weights, provides a clear understanding of what is going on and lucid explanations for the choices.
dit.unitn.it /~pgiorgio/brmae.html   (317 words)

  
 Citebase - Belief Revision and Rational Inference
The (extended) AGM postulates for belief revision seem to deal with the revision of a given theory K by an arbitrary formula, but not to constrain the revisions of two different theories by the same formula.
The AGM revisions that satisfy this new postulate stand in one-to-one correspondence with the rational, consistency-preserving relations.
Belief revisions and the ramsey test for conditionals.
www.citebase.org /cgi-bin/citations?id=oai:arXiv.org:cs/0204032   (545 words)

  
 Belief revision for resource-bounded agents   (Site not responding. Last check: 2007-11-05)
Artificial intelligence agents are often designed as having beliefs about their environment, which (together with agents' goals) determine their behaviour.
There is a large body of work on rational belief revision (rules for changing beliefs), based on the work by Alchourron, G\"{a}rdenfors and Makinson (AGM theory).
There also exist efficient (linear time) implementations of belief revision in truth maintenance systems, but they are always presented as `logically incomplete' and falling short of perfect rationality requirements.
www.ii.uib.no /undervisning/seminar/abstracts/alechina.shtml   (240 words)

  
 Aditya Ghose: Interests in belief revision   (Site not responding. Last check: 2007-11-05)
I have been looking at belief revision when belief states are represented as default theories.
It makes it easy for belief change operations to be reversible/recoverable (I'm not convinced that this is undersirable, as some maintain).
Non-prioritized belief change operations are easily defined in this approach and the problem of iterated belief change finds a simple solution (with provably minimal change over iterated steps being an additional bonus).
www.uow.edu.au /~aditya/research/br.html   (98 words)

  
 Encyclopedia article: Belief revision   (Site not responding. Last check: 2007-11-05)
Belief revision is the changing of ones beliefs after acquiring new information.
Belief revision is researched in Artificial Intelligence (The branch of computer science that deal with writing computer programs that can solve problems creatively) in the design of rational agents (additional info and facts about rational agents).
What if the new information is in conflict with something that was previously held to be true?
www.absoluteastronomy.com /encyclopedia/b/be/belief_revision.htm   (79 words)

  
 Maurice Pagnucco's Australian Logic Summer School Material
Lecture 1: Belief Change: Introduction I --- [Monday, January 18, 1999] --- (postscript, pdf).
Lecture 2: Belief Change: Introduction to AGM Approach --- [Tuesday, January 19, 1999] --- (postscript, pdf).
Samir Chopra is delivering a course on Applied Logic concentrating on belief revision, nonmonotonic reasoning and reasoning about action.
www.cse.unsw.edu.au /~morri/LSS   (318 words)

  
 Belief Revision and Rationalizablity   (Site not responding. Last check: 2007-11-05)
"Belief Revision and Rationalizability", Theoretical Aspects of Rationality and Knowledge, Proceedings of the Seventh Conference, ed.
Abstract: We construct a dynamic epistemic model for extensive form games, which generates a hierarchy of beliefs for each player over her opponents' strategies and beliefs, and tells us how those beliefs will be revised as the game proceeds.
We use the model to analyze the implications of assuming that the players possess common belief in rationality, thus extending the concept of rationalizability to extensive form games.
www.pitt.edu /~ojboard/papers/ratabs.html   (108 words)

  
 GBR - Genetic Belief Revision
GBR (Genetic Belief Revisor) is a system that performs belief revision by means of a multi-agent genetic algorithm.
In order to solve a belief revision problem by means of a genetic algorithm, the beliefs are coded as genes in a chromosome and the fitness function that is used is represented by the number of integrity constraints that are satisfied over the total number of constraints.
This procedure differs from the belief revision procedure in [5] becausethe Lamarckian operator performs a trade-off between the accuracy of the revision and the computation time: it finds a revision of the theory that is not perfect (usually it satisfies some more constraints) but it takes less time that a full revision.
lia.deis.unibo.it /Software/gbr   (482 words)

  
 Belief Revision by Lamarckian Evolution   (Site not responding. Last check: 2007-11-05)
We propose a multi-agent genetic algorithm to accomplish belief revision.
These self mutations are performed as a consequence of the chromosome phenotype's experience obtained while solving a belief revision problem.
They are directed by a belief revision procedure which relies on tracing the logical derivations leading to inconsistency of belief, so as to remove the latter's support on the gene coded assumptions, by mutating the genes.
www.cs.bris.ac.uk /~ILPnet2/Tools/Reports/Abstracts/evolearn.html   (150 words)

  
 Frontiers in Belief Revision   (Site not responding. Last check: 2007-11-05)
Frontiers in Belief Revision is a unique collection of leading edge research in Belief Revision.
The book addresses foundational issues of inductive reasoning and minimal change, generalizations of the standard belief revision theories, strategies for iterated revisions, probabilistic beliefs, multi-agent environments and a variety of data structures and mechanisms for implementations.
This book is suitable for students and researchers interested in knowledge representation and in the state of the art of the theory and practice of belief revision.
www.deit.univpm.it /~dragoni/recensioni/frontiers.htm   (106 words)

  
 Belief revision and dynamic logic
Typically, the negation of phi is in T and has to be 'retracted'.
A fairly recent way to model belief revision is within more general theories of action and change such as dynamic logic, as sketched first in 'Two traditions in the logic of belief: bringing them together', by Segerberg (1996, and 1999).
Such dynamic (and generally epistemic) approaches allow in a natural fashion for multi-agent belief revision, for belief revision with epistemic beliefs (typically: of other agents), and provide refreshing insights on irrevocable belief revision and iterated belief revision.
www.irit.fr /~Andreas.Herzig/Esslli05/Cfp.html   (481 words)

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