128,902 research outputs found
Probabilistic Default Reasoning with Conditional Constraints
We propose a combination of probabilistic reasoning from conditional
constraints with approaches to default reasoning from conditional knowledge
bases. In detail, we generalize the notions of Pearl's entailment in system Z,
Lehmann's lexicographic entailment, and Geffner's conditional entailment to
conditional constraints. We give some examples that show that the new notions
of z-, lexicographic, and conditional entailment have similar properties like
their classical counterparts. Moreover, we show that the new notions of z-,
lexicographic, and conditional entailment are proper generalizations of both
their classical counterparts and the classical notion of logical entailment for
conditional constraints.Comment: 8 pages; to appear in Proceedings of the Eighth International
Workshop on Nonmonotonic Reasoning, Special Session on Uncertainty Frameworks
in Nonmonotonic Reasoning, Breckenridge, Colorado, USA, 9-11 April 200
On the Modelling of an Agent's Epistemic State and its Dynamic Changes
Given a set of unquantified conditionals considered as default rules
or a set of quantified conditionals such as probabilistic rules, an
agent can build up its internal epistemic state from such a knowledge
base by inductive reasoning techniques. Besides certain (logical) knowledge,
epistemic states are supposed to allow the representation of preferences,
beliefs, assumptions etc. of an intelligent agent. If the agent lives in
a dynamic environment, it has to adapt its epistemic state constantly to
changes in the surrounding world in order to be able to react adequately
to new demands. In this paper, we present a high-level specification of
the Condor system that provides powerful methods and tools for managing
knowledge represented by conditionals and the corresponding epistemic
states of an agent. Thereby, we are able to elaborate and formalize
crucial interdependencies between different aspects of knowledge
representation, knowledge discovery, and belief revision. Moreover,
this specification, using Gurevich's Abstract State Machines, provides
the basis for a stepwise refinement development process of the Condor
system based on the ASM methodology
Nonmonotonic Probabilistic Logics between Model-Theoretic Probabilistic Logic and Probabilistic Logic under Coherence
Recently, it has been shown that probabilistic entailment under coherence is
weaker than model-theoretic probabilistic entailment. Moreover, probabilistic
entailment under coherence is a generalization of default entailment in System
P. In this paper, we continue this line of research by presenting probabilistic
generalizations of more sophisticated notions of classical default entailment
that lie between model-theoretic probabilistic entailment and probabilistic
entailment under coherence. That is, the new formalisms properly generalize
their counterparts in classical default reasoning, they are weaker than
model-theoretic probabilistic entailment, and they are stronger than
probabilistic entailment under coherence. The new formalisms are useful
especially for handling probabilistic inconsistencies related to conditioning
on zero events. They can also be applied for probabilistic belief revision.
More generally, in the same spirit as a similar previous paper, this paper
sheds light on exciting new formalisms for probabilistic reasoning beyond the
well-known standard ones.Comment: 10 pages; in Proceedings of the 9th International Workshop on
Non-Monotonic Reasoning (NMR-2002), Special Session on Uncertainty Frameworks
in Nonmonotonic Reasoning, pages 265-274, Toulouse, France, April 200
A Plausibility Semantics for Abstract Argumentation Frameworks
We propose and investigate a simple ranking-measure-based extension semantics
for abstract argumentation frameworks based on their generic instantiation by
default knowledge bases and the ranking construction semantics for default
reasoning. In this context, we consider the path from structured to logical to
shallow semantic instantiations. The resulting well-justified JZ-extension
semantics diverges from more traditional approaches.Comment: Proceedings of the 15th International Workshop on Non-Monotonic
Reasoning (NMR 2014). This is an improved and extended version of the
author's ECSQARU 2013 pape
Default Logic in a Coherent Setting
In this talk - based on the results of a forthcoming paper (Coletti,
Scozzafava and Vantaggi 2002), presented also by one of us at the Conference on
"Non Classical Logic, Approximate Reasoning and Soft-Computing" (Anacapri,
Italy, 2001) - we discuss the problem of representing default rules by means of
a suitable coherent conditional probability, defined on a family of conditional
events. An event is singled-out (in our approach) by a proposition, that is a
statement that can be either true or false; a conditional event is consequently
defined by means of two propositions and is a 3-valued entity, the third value
being (in this context) a conditional probability
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