20,750 research outputs found
A Semantic Account of Rigorous Simulation
Hybrid systems are a powerful formalism for modeling cyber-physical systems. Reachability analysis is a general method for checking safety properties, especially in the presence of uncertainty and non-determinism. Rigorous simulation is a convenient tool for reachability analysis of hybrid systems. However, to serve as proof tool, a rigorous simulator must be correct wrt a clearly defined notion of reachability,which captures what is intuitively eachable in finite time. As a step towards addressing this challenge, this paper presents a rigorous simulator in the form of an operational semantics and a specification in the form of a denotational semantics. We show that, under certain conditions about the representation of enclosures, the rigorous simulator is correct. We also show that finding a representation satisfying these assumptions is non-trivial
An Evaluation of Inter-Organizational Workflow Modelling Formalisms
This paper evaluates the dynamic aspects of the UML in the context of inter-organizational workflows. Two evaluation methodologies are used. The first one is ontological and is based on the BWW (Bunge-Wand-Weber) models. The second validation is based on prototyping and consists in the development of a workflow management system in the aerospace industry. Both convergent and divergent results are found from the two validations. Possible enhancements to the UML formalism are suggested from the convergent results. On the other hand, the divergent results suggest the need for a contextual specification in the BWW models. Ce travail consiste en une évaluation des aspects dynamiques du language UML dans un contexte de workflow inter-organisationnel. Le choix du language par rapport à d'autres est motivé par sa richesse grammaticale lui offrant une trÚs bonne adaptation à ce contexte. L'évaluation se fait par une validation ontologique basée sur les modÚles BWW (Bunge-Wand-Weber) et par la réalisation d'un prototype de systÚme de gestion de workflows inter-organisationnels. à partir des résultats convergents obtenus des deux différentes analyses, des améliorations au formalisme UML sont suggérées. D'un autre coté, les analyses divergentes suggÚrent une possibilité de spécifier les modÚles BWW à des contextes plus particuliers tels que ceux des workflows et permettent également de suggérer d'autres améliorations possibles au langage.Ontology, Conceptual study, Prototype Validation, UML, IS development methods and tools., Ontologie, étude conceptuelle, validation du prototype, UML, méthodes et outils de développement IS
'Playing robot': an interactive sound installation in human-robot interaction design for new media art
In this study artistic human-robot interaction design is in- troduced as a means for scientific research and artistic inves- tigations. It serves as a methodology for situated cognition integrating empirical methodology and computational mod- eling, and is exemplified by the installation playing robot. Its artistic purpose is to aid to create and explore robots as a new medium for art and entertainment. We discuss the use of finite state machines to organize robotsâ behavioral reac- tions to sensor data, and give a brief outlook on structured observation as a potential method for data collection
Hybrid analytical/numerical coupled-mode modeling of guided-wave devices
A general version of coupled-mode-theory for frequency domain scattering problems in integrated optics is proposed. As a prerequisite a physically reasonable field template is required, that typically combines modes of the optical channels in the structure with coefficient functions of in principle arbitrary coordinates. Upon 1-D discretizations of these amplitude functions into finite elements, a Galerkin procedure reduces the problem to a system of linear equations in the element coefficients, where given input amplitudes are included. Smooth approximate solutions are obtained by solving the system in a least squares sense. The versatility of the approach is illustrated by means of a series of 2-D examples, including a perpendicular crossing of waveguides, and a grating-assisted rectangular resonator. As an appendix, we show that alternatively a similar procedure can be derived by variational means, i.e. by restricting a suitable functional representation of the full 2-D/3-D vectorial scattering problem (with transparent influx boundary conditions for inhomogeneous exterior) to the respective field templates.\u
Density functional theory for strongly-correlated bosonic and fermionic ultracold dipolar and ionic gases
We introduce a density functional formalism to study the ground-state
properties of strongly-correlated dipolar and ionic ultracold bosonic and
fermionic gases, based on the self-consistent combination of the weak and the
strong coupling limits. Contrary to conventional density functional approaches,
our formalism does not require a previous calculation of the interacting
homogeneous gas, and it is thus very suitable to treat systems with tunable
long-range interactions. Due to its asymptotic exactness in the regime of
strong correlation, the formalism works for systems in which standard
mean-field theories fail.Comment: 5 pages, 2 figure
Mathematics as the role model for neoclassical economics (Blanqui Lecture)
Born out of the conscious effort to imitate mechanical physics, neoclassical economics ended up in the mid 20th century embracing a purely mathematical notion of rigor as embodied by the axiomatic method. This lecture tries to explain how this could happen, or, why and when the economistsâ role model became the mathematician rather than the physicist. According to the standard interpretation, the triumph of axiomatics in modern neoclassical economics can be explained in terms of the disciplineâs increasing awareness of its lack of good experimental and observational data, and thus of its intrinsic inability to fully abide by the paradigm of mechanics. Yet this story fails to properly account for the transformation that the word ârigorâ itself underwent first and foremost in mathematics as well as for the existence of a specific motivation behind the economistsâ decision to pursue the axiomatic route. While the full argument is developed in Giocoli 2003, these pages offer a taste of a (partially) alternative story which begins with the so-called formalist revolution in mathematics, then crosses the economistsâ almost innate urge to bring their discipline to the highest possible level of generality and conceptual integrity, and ends with the advent and consolidation of that very core set of methods, tools and ideas that constitute the contemporary image of economics.Axiomatic method, formalism, rationality, neoclassical economics
Applying Formal Methods to Networking: Theory, Techniques and Applications
Despite its great importance, modern network infrastructure is remarkable for
the lack of rigor in its engineering. The Internet which began as a research
experiment was never designed to handle the users and applications it hosts
today. The lack of formalization of the Internet architecture meant limited
abstractions and modularity, especially for the control and management planes,
thus requiring for every new need a new protocol built from scratch. This led
to an unwieldy ossified Internet architecture resistant to any attempts at
formal verification, and an Internet culture where expediency and pragmatism
are favored over formal correctness. Fortunately, recent work in the space of
clean slate Internet design---especially, the software defined networking (SDN)
paradigm---offers the Internet community another chance to develop the right
kind of architecture and abstractions. This has also led to a great resurgence
in interest of applying formal methods to specification, verification, and
synthesis of networking protocols and applications. In this paper, we present a
self-contained tutorial of the formidable amount of work that has been done in
formal methods, and present a survey of its applications to networking.Comment: 30 pages, submitted to IEEE Communications Surveys and Tutorial
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