Dagstuhl Seminar Proceedings, Volume 7351
Dagstuhl Seminar Proceedings
DagSemProc
https://www.dagstuhl.de/dagpub/1862-4405
https://dblp.org/db/series/dagstuhl
1862-4405
Schloss Dagstuhl – Leibniz-Zentrum für Informatik
7351
2007
https://drops.dagstuhl.de/entities/volume/DagSemProc-volume-7351
07351 Abstracts Collection – Formal Models of Belief Change in Rational Agents
From 26.08. to 30.08.2007, the Dagstuhl Seminar 07351 ``Formal Models of Belief Change in Rational Agents'' was held in the International Conference and Research Center (IBFI), Schloss Dagstuhl.
During the seminar, several participants presented their current
research, and ongoing work and open problems were discussed. Abstracts of
the presentations given during the seminar as well as abstracts of
seminar results and ideas are put together in this paper. The first section
describes the seminar topics and goals in general.
Links to extended abstracts or full papers are provided, if available.
Belief change
rational agents
information economy
information processing
1-18
Regular Paper
Giacomo
Bonanno
Giacomo Bonanno
James
Delgrande
James Delgrande
Jérôme
Lang
Jérôme Lang
Hans
Rott
Hans Rott
10.4230/DagSemProc.07351.1
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07351 Executive Summary – Formal Models of Belief Change in Rational Agents
From August 26, 2007 to August 30, 2007, the Dagstuhl Seminar 07351
"Formal Models of Belief Change in Rational Agents" was held at the
International Conference and Research Center (IBFI), Schloss Dagstuhl.
During the seminar, several participants presented their current
research, and ongoing work and open problems were discussed.
The Executive Summary describes the seminar topics and goals in general.
Abstracts of the presentations given during the seminar as well as abstracts of
seminar results and ideas are put together in the Proceedings.
Links to extended abstracts or full papers are provided, if available.
Belief revision
iterated belief revision
update
merging
dynamic logic
epistemic logic,conditionals
social choice
game theory
1-6
Regular Paper
Giacomo
Bonanno
Giacomo Bonanno
James
Delgrande
James Delgrande
Jérôme
Lang
Jérôme Lang
Hans
Rott
Hans Rott
10.4230/DagSemProc.07351.2
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A blueprint for deontic logic in three (not necessarily easy) steps
The famous AGM paradigm for the analysis of theory change drew its inspiration from two sources: belief change and norm change. But very early on, interest in the former eclipsed the interest in the latter. Now, many years later, it is appropriate once again to raise the question about norm change. In the author’s terminology, given the current work in Dynamic Doxastic Logic, what might Dynamic Deontic Logic look like?
Belief change
norm change
Dynamic Doxastic Logic
Dynamic Deontic Logic
1-14
Regular Paper
Krister
Segerberg
Krister Segerberg
10.4230/DagSemProc.07351.3
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A conceptual framework for (iterated) revision, update, and nonmonotonic reasoning
This paper makes a foundational contribution to the discussions on the very nature of belief change operations. Belief revision and belief update are investigated within an abstract framework of epistemic states and (qualitative or quantitative) conditionals. Moreover, we distinguish between background knowledge and contextual information in order to analyse belief change more appropriately. The rich epistemic representation framework allows us to make a clear conceptual distinction between revision and update on the one side, while revealing structural similarities on the other side. We propose generic postulates for revision and update that also apply to iterated change. Furthermore, we complete the unifying picture by introducing universal inference operations as a proper counterpart in nonmonotonic reasoning to iterated belief change.
Belief revision
belief update
nonmonotonic inference
epistemic states
conditionals
1-0
Regular Paper
Gabriele
Kern-Isberner
Gabriele Kern-Isberner
10.4230/DagSemProc.07351.4
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A logical formalism for the subjective approach in a multi-agent setting
Representing an epistemic situation involving several agents depends very much on the modeling point of view one takes. In fact, the interpretation of a formalism relies quite a lot on the nature of this modeling point of view. Classically, in epistemic logic, the models built are supposed to represent the situation from an external and objective point of view. We call this modeling approach the objective approach. In this paper, we study the modeling point of view of a particular agent involved in the situation with other agents. We propose a logical formalism based on epistemic logic that this agent can use to represent `for herself' the surrounding world. We call this modeling approach the subjective approach. We then set some formal connections between the subjective approach and the objective approach. Finally we axiomatize our logical formalism and show that the resulting logic is decidable.
Epistemic logic
multi-agent system
1-0
Regular Paper
Guillaume
Aucher
Guillaume Aucher
10.4230/DagSemProc.07351.5
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A Method for Reasoning about other Agents' Beliefs from Observations
Traditional work in belief revision deals with the question of what an agent should believe upon receiving new information. We will give an overview about what can be concluded about an agent based on an observation of its belief revision behaviour. The observation contains partial information about the revision inputs received by the agent and its beliefs upon receiving them. We will sketch a method for reasoning about past and future beliefs of the agent and predicting which inputs it accepts and rejects. The focus of this talk will be on different degrees of incompleteness of the observation and variants of the general question we are able to deal with.
Belief revision
iterated revision
non-prioritised revision
non-monotonic reasoning
rational closure
rational explanation
1-5
Regular Paper
Alexander
Nittka
Alexander Nittka
Richard
Booth
Richard Booth
10.4230/DagSemProc.07351.6
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Belief Change and Cryptographic Protocol Verification
Cryptographic protocols are structured sequences of messages that are used for
exchanging information in a hostile environment. Many protocols have epistemic
goals: a successful run of the protocol is intended to cause a participant to hold
certain beliefs. As such, epistemic logics have been employed for the verification
of cryptographic protocols. Although this
approach to verification is explicitly concerned with changing
beliefs, formal belief change operators have not been incorporated in previous work.
In this paper, we introduce a new approach to protocol verification
by combining a monotonic logic with a non-monotonic belief change
operator. In this context, a protocol participant is able to retract beliefs
in response to new information and a protocol participant is able to postulate
the most plausible event explaining new information. We illustrate that this kind of reasoning
is particularly important when protocol participants have incorrect beliefs.
Belief change
belief evolution
cryptographic protocol verification
1-14
Regular Paper
Aaron
Hunter
Aaron Hunter
James
Delgrande
James Delgrande
10.4230/DagSemProc.07351.7
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Common Foundations for belief revision, belief merging and voting
In this paper, we consider a number of different ways of reasoning about voting as a problem of conciliating contradictory interests. The mechanisms that do the reconciliation are belief revision and belief merging. By investigating the relationship between different voting strategies and their associated counterparts in revision theory, we find that whereas the counting mechanism of the voting process is more easily done at the meta-level in belief merging, it can be brought to the object level in base revision. In the former case, the counting can be tweaked according to the aggregation procedure used, whereas in base revision, we can only rely on the notion of minimal change and hence the syntactical representation of the voters' preferences plays a crucial part in the process. This highlights the similarities between the revision approaches on the one hand and voting on the other, but also opens up a number of interesting questions.
Belief revision
belief merging
voting
social choice theory
1-16
Regular Paper
Dov
Gabbay
Dov Gabbay
Gabriella
Pigozzi
Gabriella Pigozzi
Odinaldo
Rodrigues
Odinaldo Rodrigues
10.4230/DagSemProc.07351.8
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Distance Semantics for Relevance-Sensitive Belief Revision
Parikh's axiom (P) for relevance-sensitive belief revision is studied. Sound and complete semantics for axiom (P) is provided in the form constraints on system-of-spheres.
Belief Revision
System of Spheres.
1-9
Regular Paper
Pavlos
Peppas
Pavlos Peppas
Samir
Chopra
Samir Chopra
Norman
Foo
Norman Foo
10.4230/DagSemProc.07351.9
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Dynamic Interactions Between Goals and Beliefs
Shapiro et al. [2005], presented a framework for representing goal change in the situation calculus. In that framework, agents adopt a goal when requested to do so (by some agent reqr), and they remain committed to the goal unless the request is cancelled by reqr. A common assumption in the agent theory literature, is that achievement goals that are believed to be impossible to achieve should be dropped. In this paper, we incorporate this assumption into Shapiro et al.'s framework, however we go a step further. If an agent believes a goal is impossible to achieve, it is dropped. However, if the agent later believes that it was mistaken about the impossibility of achieving the goal, the agent might readopt the goal. In addition, we consider an agent's goals as a whole when making them compatible with their beliefs, rather than considering them individually.
Goal Change
Belief Change
Situation Calculus
1-9
Regular Paper
Steven
Shapiro
Steven Shapiro
Gerhard
Brewka
Gerhard Brewka
10.4230/DagSemProc.07351.10
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Enhanced Contraction and (In)dependence Preliminary report
We introduce a number of contraction operations that allow us to preserve more information in the process of belief contraction and revision of our epistemic states. One of them, choice contraction, will be argued to characterise basic (in)dependence relations among propositions belonging to the epistemic state.
Contractions
dependence
1-4
Regular Paper
Alexander
Bochman
Alexander Bochman
10.4230/DagSemProc.07351.11
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Forgetting and Update – an exploration
Knowledge Update (respectively Erasure) and Forgetting are two very
different concepts, with very different underlying motivation. Both are tools for knowledge management; however while the former is meant for accommodating new knowledge into a knowledge corpus, the latter is meant for modifying – in fact reducing the expressivity – of the underlying language. In this paper we show that there is an intimate connection between these two concepts: a particular form of knowledge update and literal forgetting are inter-definable. This connection is exploited to enhance both our understanding of update as well as forgetting in this paper.
Knowledge Update
Erasure
Forgetting
Dalal Distance
Winslett Distance.
1-14
Regular Paper
Abhaya
Nayak
Abhaya Nayak
Yin
Chen
Yin Chen
Fangzhen
Lin
Fangzhen Lin
10.4230/DagSemProc.07351.12
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From belief change to preference change
There is a huge literature on belief change. In contrast, preference change has been considered only in a few recent papers. There are reasons for that: while there is to some extent a general agreement about the very meaning of belief change, this is definitely not so for preference change. We discuss here the possible meanings of preference change, arguing that we should at least distinguish between four paradigms: preferences evolving after some new fact has been learned, preferences evolving as a result of an evolution of the world, preferences evolving after the rational agent itself evolves, and preferences evolving per se. We then develop in more detail the first of these four paradigms (which we think is the most natural). We give some natural properties that we think preference change should fulfill and define several families of preference change operators, parameterized by a revision function on epistemic states and a semantics for interpreting preferences over formulas.
Beliefs
preferences
decision making
agents
preference revision
1-8
Regular Paper
Jérôme
Lang
Jérôme Lang
Leendert
van der Torre
Leendert van der Torre
10.4230/DagSemProc.07351.13
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Measuring Ranks via the Complete Laws of Iterated Contraction
Ranking theory delivers an account of iterated contraction; each ranking function induces a specific iterated contraction behavior. The paper gives a complete axiomatization of that behavior, i.e., a complete set of laws of iterated contraction. It does so by showing how to reconstruct a ranking function from its iterated contraction behavior uniquely up to multi-plicative constant and thus how to measure ranks on a ratio scale.
Ranking theory
iterated contraction
measurement theory
1-19
Regular Paper
Wolfgang
Spohn
Wolfgang Spohn
10.4230/DagSemProc.07351.14
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Optimal Regression for Reasoning about Knowledge and Actions
We show how in the propositional case both Reiter's and Scherl & Levesque's solutions to the frame problem can be modelled in dynamic epistemic logic (DEL), and provide an optimal regression algorithm for the latter.
Our method is as follows: we extend Reiter's framework by integrating observation actions and modal operators of knowledge, and encode the resulting formalism in DEL with announcement and assignment operators.
By extending Lutz' recent satisfiability-preserving reduction to our logic, we establish optimal decision procedures for both Reiter's and Scherl & Levesque's approaches:
satisfiability is NP-complete for one agent, PSPACE-complete for multiple agents and EXPTIME-complete when common knowledge is involved.
Reasoning about action and change
reasoning about knowledge
situation calculus
frame problem
dynamic epistemic logic
1-22
Regular Paper
Hans
van Ditmarsch
Hans van Ditmarsch
Andreas
Herzig
Andreas Herzig
Tiago
de Lima
Tiago de Lima
10.4230/DagSemProc.07351.15
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Premise Independence in Judgment Aggregation
Judgment aggregation studies how agent opinions on logically
interconnected propositions can be mapped into a collective judgment
on the same propositions, and is plagued by impossibility results.
In this paper we study the central notion of independence in
these impossibility results. First, we argue that the distinction
between the premises and conclusions play an important role in the
benchmark examples of judgment aggregation. Second, we consider the
notion of independence in judgment aggregation frameworks, and we
observe that the distinction between premises and conclusion is not
taken into account. Third, based on our analysis, we introduce
independence assumptions that distinguish premises from conclusion.
We show that, by introducing new operators that satisfy our independence assumptions, the problematic impossibility results no longer hold.
Judgment aggregation
social choice theory
1-8
Regular Paper
Gabriella
Pigozzi
Gabriella Pigozzi
Leendert
van der Torre
Leendert van der Torre
10.4230/DagSemProc.07351.16
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Probability Logic and Logical Probability
Authors like Keynes, H. Jeffreys and Carnap advocated using a concept of "logical probability". Logical probability had the following properties: (a) it was representable as a function from potential states of full belief (or "evidence") to states of subjective or credal probability judgment. (b) Such functions were alleged to be constrained by principles of probability logic. (c) All rational agents were supposed to be obliged to adopt the standard function that probability logic prescribed. In this essay, it is argued that these three requirements could be satisfied only if probability logic prescribed that credal probability should be numerically determinate. Keynes denied that it should numerically determinate and Carnap abandoned the idea that probability logic could supply a determinate function from states of full belief to numerically determinate credal states that all rational agents ought to adopt. The paper explains that once this is conceded, logical probability ought to be interpreted rather differently than it is customarily is.
Probability
full belief
logic
evidence
1-27
Regular Paper
Isaac
Levi
Isaac Levi
10.4230/DagSemProc.07351.17
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Propositional Relevance through Letter-Sharing: Review and Contribution
The concept of relevance between classical propositional formulae, defined in terms of letter-sharing, has been around for a very long time. But it began to take on a fresh life in 1999 when it was reconsidered in the context of the logic of belief change. Two new ideas appeared in independent work of Odinaldo Rodrigues and Rohit Parikh. First, the relation of relevance was considered modulo the belief set under consideration, Second, the belief set was put in a canonical form, known as its finest splitting. In this paper we explain these ideas; relate the approaches of Rodrigues and Parikh to each other; and briefly report some recent results of Kourousias and Makinson on the extent to which AGM belief change operations respect relevance. Finally we suggest a further refinement of the notion of relevance by introducing a parameter that allows one to take epistemic as well as purely logical components into account.
Belief change
relevance
letter-sharing
splitting
1-13
Regular Paper
David
Makinson
David Makinson
10.4230/DagSemProc.07351.18
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Ranking Revision Reloaded
In the context of a general revision framework, we propose and take a first look at revision strategies for epistemic ranking measures reaching beyond minimal Jeffrey-conditionalization, a variant of Spohn-style revision.
Ranking measures
iterated belief revision
1-7
Regular Paper
Emil
Weydert
Emil Weydert
10.4230/DagSemProc.07351.19
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Semantic structures for one-stage and iterated belief revision
Semantic structures for belief revision and iterated
belief revision are proposed. We start with one-stage
revision structures that generalize the notion of
choice function from rational choice theory. A
correspondence between these one-stage structures and
AGM belief revision functions is established. We then
add branching time and consider more general structures
that accommodate iterated revision. AGM temporal belief revision
structures are defined and a syntactic axiomatization is
provided.
Iterated belief revision
choice functions
Kripke semantics
branching time
modal logic
1-14
Regular Paper
Giacomo
Bonanno
Giacomo Bonanno
10.4230/DagSemProc.07351.20
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The Logic of Bargaining
This paper reexamines the game-theoretic bargaining theory from
logic and Artificial Intelligence perspectives. We present an
axiomatic characterization of the logical solutions to bargaining
problems. A bargaining situation is described in propositional logic
with numerical representation of bargainers' preferences. A solution
to the n-person bargaining problems is proposed based on the
maxmin rule over the degrees of bargainers' satisfaction. The
solution is uniquely characterized by four axioms collective
rationality, scale invariance, symmetry and
mutually comparable monotonicity in conjunction with three
other fundamental assumptions individual rationality,
consistency and comprehensiveness. The Pareto
efficient solutions are characterized by the axioms scale
invariance, Pareto optimality and restricted mutually
comparable monotonicity along with the basic assumptions. The
relationships of these axioms and assumptions and their links to
belief revision postulates and game theory axioms are discussed. The
framework would help us to identify the logical reasoning behind
bargaining processes and would initiate a new methodology of
bargaining analysis.
Bargaining theory
belief revision
game theory
1-34
Regular Paper
Dongmo
Zhang
Dongmo Zhang
10.4230/DagSemProc.07351.21
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Two-Dimensional Belief Change
The idea of two-dimensional belief change operators is that a belief state is
transformed by an input sentence $A$ in such a way that $A$ gets accepted
with at least the strength or certainty of a sentence $B$ (the reference
sentence). The input of such a transformation may alternatively be conceived
as `$B leq A$' [`$B$ less-than-or-equal-to $A$']. This notation makes explicit
that the process induced is basically one of doxastic preference change. The
principal case of two-dimensional belief change obtains when $B$ is a prior
belief which is more strongly accepted than both $A$ and $
eg A$, but the
non-principal cases are interesting in their own right. Various two-dimensional
revision operators were studied by Cantwell (1997, `raising' and `lowering'),
FermÃƒÂ© and Rott (2003, `revision by comparison'), and Rott (2007, `bounded
revision'). Special choices of a fixed input sentence $A$ or a fixed reference
sentence $B$ lead to some well-known unary oparators of belief change:
`irrevocable' (aka `radical') revision, `severe withdrawal' (aka `mild
contraction'), `natural' (aka `conservative') and `lexicographic' (aka `moderate')
revision. The talk gives a survey of several variants of two-dimensional belief
change and their representations. I argue that two-dimensional belief change
operators offer an interesting qualitative model with an expressive power
between (all too poor) unary operators and (all too demanding) quantitative
models of belief change.
Belief revision
radical revision
conservative revision
moderate revision
severe withdrawal
preference change
qualitative vs. quantitative change
1-27
Regular Paper
Hans
Rott
Hans Rott
10.4230/DagSemProc.07351.22
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