5,426 research outputs found
Embedding Non-Ground Logic Programs into Autoepistemic Logic for Knowledge Base Combination
In the context of the Semantic Web, several approaches to the combination of
ontologies, given in terms of theories of classical first-order logic and rule
bases, have been proposed. They either cast rules into classical logic or limit
the interaction between rules and ontologies. Autoepistemic logic (AEL) is an
attractive formalism which allows to overcome these limitations, by serving as
a uniform host language to embed ontologies and nonmonotonic logic programs
into it. For the latter, so far only the propositional setting has been
considered. In this paper, we present three embeddings of normal and three
embeddings of disjunctive non-ground logic programs under the stable model
semantics into first-order AEL. While the embeddings all correspond with
respect to objective ground atoms, differences arise when considering
non-atomic formulas and combinations with first-order theories. We compare the
embeddings with respect to stable expansions and autoepistemic consequences,
considering the embeddings by themselves, as well as combinations with
classical theories. Our results reveal differences and correspondences of the
embeddings and provide useful guidance in the choice of a particular embedding
for knowledge combination.Comment: 52 pages, submitte
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
Dynamic criticality at the jamming transition
We characterize vibrational motion occurring at low temperatures in dense
suspensions of soft repulsive spheres over a broad range of volume fractions
encompassing the jamming transition at (T = 0, phi = phi_J). We find that
characteristic time and length scales of thermal vibrations obey critical
scaling in the vicinity of the jamming transition. We show in particular that
the amplitude and the time scale of dynamic fluctuations diverge symmetrically
on both sides of the transition, and directly reveal a diverging correlation
length. The critical region near phi_J is divided in three different regimes
separated by a characteristic temperature scale T*(phi) that vanishes
quadratically with the distance to phi_J. While two of them, (T < T*(phi), phi
> phi_J) and (T < T*(phi), phi < phi_J), are described by harmonic theories
developed in the zero temperature limit, the third one for T > T*(phi) is
inherently anharmonic and displays new critical properties. We find that the
quadratic scaling of T*(phi) is due to nonperturbative anharmonic
contributions, its amplitude being orders of magnitude smaller than the
perturbative prediction based on the expansion to quartic order in the
interactions. Our results show that thermal vibrations in colloidal assemblies
directly reveal the critical nature of the jamming transition. The critical
region, however, is very narrow and has not yet been attained experimentally,
even in recent specifically-dedicated experiments.Comment: 18 pages; submitted to J. Chem. Phys. for "Special Topic Issue on the
Glass Transition
- …