39 research outputs found
Contextual and Possibilistic Reasoning for Coalition Formation
In multiagent systems, agents often have to rely on other agents to reach
their goals, for example when they lack a needed resource or do not have the
capability to perform a required action. Agents therefore need to cooperate.
Then, some of the questions raised are: Which agent(s) to cooperate with? What
are the potential coalitions in which agents can achieve their goals? As the
number of possibilities is potentially quite large, how to automate the
process? And then, how to select the most appropriate coalition, taking into
account the uncertainty in the agents' abilities to carry out certain tasks? In
this article, we address the question of how to find and evaluate coalitions
among agents in multiagent systems using MCS tools, while taking into
consideration the uncertainty around the agents' actions. Our methodology is
the following: We first compute the solution space for the formation of
coalitions using a contextual reasoning approach. Second, we model agents as
contexts in Multi-Context Systems (MCS), and dependence relations among agents
seeking to achieve their goals, as bridge rules. Third, we systematically
compute all potential coalitions using algorithms for MCS equilibria, and given
a set of functional and non-functional requirements, we propose ways to select
the best solutions. Finally, in order to handle the uncertainty in the agents'
actions, we extend our approach with features of possibilistic reasoning. We
illustrate our approach with an example from robotics
On the KLM properties of a fuzzy DL with Typicality
The paper investigates the properties of a fuzzy logic of typicality. The
extension of fuzzy logic with a typicality operator was proposed in recent work
to define a fuzzy multipreference semantics for Multilayer Perceptrons, by
regarding the deep neural network as a conditional knowledge base. In this
paper, we study its properties. First, a monotonic extension of a fuzzy ALC
with typicality is considered (called ALC^FT) and a reformulation the KLM
properties of a preferential consequence relation for this logic is devised.
Most of the properties are satisfied, depending on the reformulation and on the
fuzzy combination functions considered. We then strengthen ALC^FT with a
closure construction by introducing a notion of faithful model of a weighted
knowledge base, which generalizes the notion of coherent model of a conditional
knowledge base previously introduced, and we study its properties.Comment: 15 page
Preferential Multi-Context Systems
Multi-context systems (MCS) presented by Brewka and Eiter can be considered
as a promising way to interlink decentralized and heterogeneous knowledge
contexts. In this paper, we propose preferential multi-context systems (PMCS),
which provide a framework for incorporating a total preorder relation over
contexts in a multi-context system. In a given PMCS, its contexts are divided
into several parts according to the total preorder relation over them,
moreover, only information flows from a context to ones of the same part or
less preferred parts are allowed to occur. As such, the first preferred
parts of an PMCS always fully capture the information exchange between contexts
of these parts, and then compose another meaningful PMCS, termed the
-section of that PMCS. We generalize the equilibrium semantics for an MCS to
the (maximal) -equilibrium which represents belief states at least
acceptable for the -section of an PMCS. We also investigate inconsistency
analysis in PMCS and related computational complexity issues
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