1,093 research outputs found
Properties of ABA+ for Non-Monotonic Reasoning
We investigate properties of ABA+, a formalism that extends the well studied
structured argumentation formalism Assumption-Based Argumentation (ABA) with a
preference handling mechanism. In particular, we establish desirable properties
that ABA+ semantics exhibit. These pave way to the satisfaction by ABA+ of some
(arguably) desirable principles of preference handling in argumentation and
nonmonotonic reasoning, as well as non-monotonic inference properties of ABA+
under various semantics.Comment: This is a revised version of the paper presented at the worksho
Improved Answer-Set Programming Encodings for Abstract Argumentation
The design of efficient solutions for abstract argumentation problems is a
crucial step towards advanced argumentation systems. One of the most prominent
approaches in the literature is to use Answer-Set Programming (ASP) for this
endeavor. In this paper, we present new encodings for three prominent
argumentation semantics using the concept of conditional literals in
disjunctions as provided by the ASP-system clingo. Our new encodings are not
only more succinct than previous versions, but also outperform them on standard
benchmarks.Comment: To appear in Theory and Practice of Logic Programming (TPLP),
Proceedings of ICLP 201
On Stalnaker's "Indicative Conditionals"
This paper is a guide to the main ideas and innovations in Robert Stalnaker's "Indicative Conditionals". The paper is for a volume of essays on twenty-one classics of formal semantics edited by Louise McNally and Zoltà n Gendler Szab
On resolving conflicts between arguments
Argument systems are based on the idea that one can construct arguments for
propositions; i.e., structured reasons justifying the belief in a proposition.
Using defeasible rules, arguments need not be valid in all circumstances,
therefore, it might be possible to construct an argument for a proposition as
well as its negation. When arguments support conflicting propositions, one of
the arguments must be defeated, which raises the question of \emph{which
(sub-)arguments can be subject to defeat}?
In legal argumentation, meta-rules determine the valid arguments by
considering the last defeasible rule of each argument involved in a conflict.
Since it is easier to evaluate arguments using their last rules, \emph{can a
conflict be resolved by considering only the last defeasible rules of the
arguments involved}?
We propose a new argument system where, instead of deriving a defeat relation
between arguments, \emph{undercutting-arguments} for the defeat of defeasible
rules are constructed. This system allows us, (\textit{i}) to resolve conflicts
(a generalization of rebutting arguments) using only the last rules of the
arguments for inconsistencies, (\textit{ii}) to determine a set of valid
(undefeated) arguments in linear time using an algorithm based on a JTMS,
(\textit{iii}) to establish a relation with Default Logic, and (\textit{iv}) to
prove closure properties such as \emph{cumulativity}. We also propose an
extension of the argument system that enables \emph{reasoning by cases}
Reasoning about exceptions in ontologies: from the lexicographic closure to the skeptical closure
Reasoning about exceptions in ontologies is nowadays one of the challenges
the description logics community is facing. The paper describes a preferential
approach for dealing with exceptions in Description Logics, based on the
rational closure. The rational closure has the merit of providing a simple and
efficient approach for reasoning with exceptions, but it does not allow
independent handling of the inheritance of different defeasible properties of
concepts. In this work we outline a possible solution to this problem by
introducing a variant of the lexicographical closure, that we call skeptical
closure, which requires to construct a single base. We develop a bi-preference
semantics semantics for defining a characterization of the skeptical closure
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