53 research outputs found
Epistemic entrenchment-based multiple contractions
In this article we present a new class of multiple contraction functions—the epistemic entrenchment-based multiple contractions—which are a generalization of the epistemic
entrenchment-based contractions (Gardenfors, 1988; G ¨ ardenfors & Makinson, 1988) to the case of ¨
contractions by (possibly nonsingleton) sets of sentences and provide an axiomatic characterization
for that class of functions. Moreover, we show that the class of epistemic entrenchment-based multi ple contractions coincides with the class of system of spheres-based multiple contractions introduced
in Ferme & Reis (2012).info:eu-repo/semantics/publishedVersio
System of spheres-based multiple contractions
We propose a new class of multiple contraction operations — the
system of spheres-based multiple contractions — which are a generalization
of Grove’s system of spheres-based (singleton) contractions to the case of
contractions by (possibly non-singleton) sets of sentences. Furthermore, we
show that this new class of functions is a subclass of the class of the partial
meet multiple contractions.info:eu-repo/semantics/publishedVersio
Possible worlds semantics for partial meet multiple contraction
In the logic of theory change, the standard model is AGM, proposed
by Alchourrón et al. (J Symb Log 50:510–530, 1985). This paper focuses
on the extension of AGM that accounts for contractions of a theory by
a set of sentences instead of only by a single sentence. Hansson (Theoria
55:114–132, 1989), Fuhrmann and Hansson (J Logic Lang Inf 3:39–74, 1994)
generalized Partial Meet Contraction to the case of contractions by (possibly
non-singleton) sets of sentences. In this paper we present the possible worlds
semantics for partial meet multiple contractions.info:eu-repo/semantics/publishedVersio
Residual contraction
In this paper, we propose and axiomatically characterize residual
contractions, a new kind of contraction operators for belief bases. We establish
that the class of partial meet contractions is a strict subclass of the class of
residual contractions. We identify an extra condition that may be added to
the definition of residual contractions, which is such that the class of residual
contractions that satisfy it coincides with the class of partial meet contrac tions. We investigate the interrelations in the sense of (strict) inclusion among
the class of residual contractions and other classes of well known contraction
operators for belief bases.info:eu-repo/semantics/publishedVersio
System of Spheres-based Two Level Credibility-limited Revisions
Two level credibility-limited revision is a non-prioritized revision
operation. When revising by a two level credibility-limited revision, two
levels of credibility and one level of incredibility are considered. When
revising by a sentence at the highest level of credibility, the operator
behaves as a standard revision, if the sentence is at the second level of
credibility, then the outcome of the revision process coincides with a standard
contraction by the negation of that sentence. If the sentence is not credible,
then the original belief set remains unchanged. In this paper, we propose a
construction for two level credibility-limited revision operators based on
Grove's systems of spheres and present an axiomatic characterization for these
operators.Comment: In Proceedings TARK 2023, arXiv:2307.0400
Two axiomatic characterizations for the system of spheres-based (and the Epistemic Entrenchment-based) multiple contractions
t In some recent works (Reis 2011, Ferme and Reis, J. Philos. Log. ´ 41, 29–52,
2012, Ferme and Reis, Rev. Symb. Log. ´ 6, 460–487, 2013) two new kinds of multiple
contraction functions have been proposed, namely the system of spheres-based multiple
contractions and the epistemic entrenchment-based multiple contractions, as generalizations
(to the case of multiple contraction) of the well-known classes of systems of spheres-based
and of epistemic entrenchment-based (singleton) contractions. Additionally, a representa tion theorem for the class of epistemic entrenchment-based multiple contraction has been
proposed, and it has been shown that the two newly proposed constructions are equivalent, in
the sense that a multiple contraction function is a system of spheres-based multiple contrac tion if and only if it is an epistemic entrenchment-based multiple contraction. In this paper
we present two axiomatic characterizations for those multiple contraction functions which
differ from the one mentioned above and, in particular, make use of some more intuitive
postulates.info:eu-repo/semantics/publishedVersio
Levi and Harper identities for non-prioritized belief base change
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].info:eu-repo/semantics/publishedVersio
Shielded base contraction
The one that is considered the standard model in the area of logic of belief change was
proposed by Alchourrón, Gärdenfors and Makinson in 1985 and is, nowadays, known as
the AGM model.
Two of the main shortcomings pointed out to the AGM model of belief change are the
(impractical) use of belief sets to represent belief states and the (unrealistic) acceptance of
any new information. In this paper we study a kind of operators—known as shielded base
contractions—which address both those issues. 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 informations are accepted.
We propose twenty different classes of shielded base contractions 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 of those classes is or is not (strictly) contained in each of the remaining ones.info:eu-repo/semantics/publishedVersio
Studies in credibility: limited base revision
In this paper we present axiomatic characterizations for several classes of credibility-limited base revision functions and establish the interrelation among those classes. We also propose and axiomatically characterize two new base revision functions.info:eu-repo/semantics/publishedVersio
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