17,517 research outputs found
Actual Causation in CP-logic
Given a causal model of some domain and a particular story that has taken
place in this domain, the problem of actual causation is deciding which of the
possible causes for some effect actually caused it. One of the most influential
approaches to this problem has been developed by Halpern and Pearl in the
context of structural models. In this paper, I argue that this is actually not
the best setting for studying this problem. As an alternative, I offer the
probabilistic logic programming language of CP-logic. Unlike structural models,
CP-logic incorporates the deviant/default distinction that is generally
considered an important aspect of actual causation, and it has an explicitly
dynamic semantics, which helps to formalize the stories that serve as input to
an actual causation problem
Modal logics are coalgebraic
Applications of modal logics are abundant in computer science, and a large number of structurally different modal logics have been successfully employed in a diverse spectrum of application contexts. Coalgebraic semantics, on the other hand, provides a uniform and encompassing view on the large variety of specific logics used in particular domains. The coalgebraic approach is generic and compositional: tools and techniques simultaneously apply to a large class of application areas and can moreover be combined in a modular way. In particular, this facilitates a pick-and-choose approach to domain specific formalisms, applicable across the entire scope of application areas, leading to generic software tools that are easier to design, to implement, and to maintain. This paper substantiates the authors' firm belief that the systematic exploitation of the coalgebraic nature of modal logic will not only have impact on the field of modal logic itself but also lead to significant progress in a number of areas within computer science, such as knowledge representation and concurrency/mobility
Verification and Control of Partially Observable Probabilistic Real-Time Systems
We propose automated techniques for the verification and control of
probabilistic real-time systems that are only partially observable. To formally
model such systems, we define an extension of probabilistic timed automata in
which local states are partially visible to an observer or controller. We give
a probabilistic temporal logic that can express a range of quantitative
properties of these models, relating to the probability of an event's
occurrence or the expected value of a reward measure. We then propose
techniques to either verify that such a property holds or to synthesise a
controller for the model which makes it true. Our approach is based on an
integer discretisation of the model's dense-time behaviour and a grid-based
abstraction of the uncountable belief space induced by partial observability.
The latter is necessarily approximate since the underlying problem is
undecidable, however we show how both lower and upper bounds on numerical
results can be generated. We illustrate the effectiveness of the approach by
implementing it in the PRISM model checker and applying it to several case
studies, from the domains of computer security and task scheduling
Discerning Elementary Particles
We extend the quantum-mechanical results of Muller & Saunders (2008)
establishing the weak discernibility of an arbitrary number of similar fermions
in finite-dimensional Hilbert-spaces in two ways: (a) from fermions to bosons
for all finite-dimensional Hilbert-spaces; and (b) from finite-dimensional to
infinite-dimensional Hilbert-spaces for all elementary particles. In both cases
this is performed using operators whose physical significance is beyond
doubt.This confutes the currently dominant view that (A) the quantum-mechanical
description of similar particles conflicts with Leibniz's Principle of the
Identity of Indiscernibles (PII); and that (B) the only way to save PII is by
adopting some pre-Kantian metaphysical notion such as Scotusian haecceittas or
Adamsian primitive thisness. We take sides with Muller & Saunders (2008)
against this currently dominant view, which has been expounded and defended by,
among others, Schr\"odinger, Margenau, Cortes, Dalla Chiara, Di Francia,
Redhead, French, Teller, Butterfield, Mittelstaedt, Giuntini, Castellani,
Krause and Huggett.Comment: Final Version. To appear in Philosophy of Science, July 200
Statistical Model Checking of e-Motions Domain-Specific Modeling Languages
Domain experts may use novel tools that allow them to de- sign and model their systems in a notation very close to the domain problem. However, the use of tools for the statistical analysis of stochas- tic systems requires software engineers to carefully specify such systems in low level and specific languages. In this work we line up both sce- narios, specific domain modeling and statistical analysis. Specifically, we have extended the e-Motions system, a framework to develop real-time domain-specific languages where the behavior is specified in a natural way by in-place transformation rules, to support the statistical analysis of systems defined using it. We discuss how restricted e-Motions sys- tems are used to produce Maude corresponding specifications, using a model transformation from e-Motions to Maude, which comply with the restrictions of the VeStA tool, and which can therefore be used to per- form statistical analysis on the stochastic systems thus generated. We illustrate our approach with a very simple messaging distributed system.Universidad de Málaga Campus de Excelencia Internacional AndalucĂa Tech. Research Project TIN2014-52034-R an
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