Propagation-Dispersion Equation

A {\em propagation-dispersion equation} is derived for the first passage distribution function of a particle moving on a substrate with time delays. The equation is obtained as the continuous limit of the {\em first visit equation}, an exact microscopic finite difference equation describing the motion of a particle on a lattice whose sites operate as {\em time-delayers}. The propagation-dispersion equation should be contrasted with the advection-diffusion equation (or the classical Fokker-Planck equation) as it describes a dispersion process in {\em time} (instead of diffusion in space) with a drift expressed by a propagation speed with non-zero bounded values. The {\em temporal dispersion} coefficient is shown to exhibit a form analogous to Taylor's dispersivity. Physical systems where the propagation-dispersion equation applies are discussed.Comment: 12 pages+ 5 figures, revised and extended versio

Online On-the-Fly Testing of Real-time Systems

In this paper we present a framework, an algorithm and a new tool for online testing of real-time systems based on symbolic techniques used in UPPAAL model checker. We extend UPPAAL timed automata network model to a test specification which is used to generate test primitives and to check the correctness of system responses including the timing aspects. We use timed trace inclusion as a conformance relation between system and specification to draw a test verdict. The test generation and execution algorithm is implemented as an extension to UPPAAL and experiments carried out to examine the correctness and performance of the tool. The experiment results are promising

Online On-the-Fly Testing of Real-time Systems

In this paper we present a framework, an algorithm and a new tool for online testing of real-time systems based on symbolic techniques used in UPPAAL model checker. We extend UPPAAL timed automata network model to a test specification which is used to generate test primitives and to check the correctness of system responses including the timing aspects. We use timed trace inclusion as a conformance relation between system and specification to draw a test verdict. The test generation and execution algorithm is implemented as an extension to UPPAAL and experiments carried out to examine the correctness and performance of the tool. The experiment results are promising

Network Latency and Packet Delay Variation in Cyber-physical Systems

The problem addressed in this paper is the limitation imposed by network elements, especially Ethernet elements, on the real-time performance of time-critical systems. Most current network elements are concerned only with data integrity, connection, and throughput with no mechanism for enforcing temporal semantics. Existing safety-critical applications and other applications in industry require varying degrees of control over system-wide temporal semantics. In addition, there are emerging commercial applications that require or will benefit from tighter enforcement of temporal semantics in network elements than is currently possible. This paper examines these applications and requirements and suggests possible approaches to imposing temporal semantics on networks. Model-based design and simulation is used to evaluate the effects of network limitations on time-critical systems

Stochastic Timed Automata

A stochastic timed automaton is a purely stochastic process defined on a timed automaton, in which both delays and discrete choices are made randomly. We study the almost-sure model-checking problem for this model, that is, given a stochastic timed automaton A and a property $\Phi$, we want to decide whether A satisfies $\Phi$ with probability 1. In this paper, we identify several classes of automata and of properties for which this can be decided. The proof relies on the construction of a finite abstraction, called the thick graph, that we interpret as a finite Markov chain, and for which we can decide the almost-sure model-checking problem. Correctness of the abstraction holds when automata are almost-surely fair, which we show, is the case for two large classes of systems, single- clock automata and so-called weak-reactive automata. Techniques employed in this article gather tools from real-time verification and probabilistic verification, as well as topological games played on timed automata.Comment: 40 pages + appendi

Integrated Information Theory and Isomorphic Feed-Forward Philosophical Zombies

Any theory amenable to scientific inquiry must have testable consequences. This minimal criterion is uniquely challenging for the study of consciousness, as we do not know if it is possible to confirm via observation from the outside whether or not a physical system knows what it feels like to have an inside - a challenge referred to as the "hard problem" of consciousness. To arrive at a theory of consciousness, the hard problem has motivated the development of phenomenological approaches that adopt assumptions of what properties consciousness has based on first-hand experience and, from these, derive the physical processes that give rise to these properties. A leading theory adopting this approach is Integrated Information Theory (IIT), which assumes our subjective experience is a "unified whole", subsequently yielding a requirement for physical feedback as a necessary condition for consciousness. Here, we develop a mathematical framework to assess the validity of this assumption by testing it in the context of isomorphic physical systems with and without feedback. The isomorphism allows us to isolate changes in $\Phi$ without affecting the size or functionality of the original system. Indeed, we show that the only mathematical difference between a "conscious" system with $\Phi>0$ and an isomorphic "philosophical zombies" with $\Phi=0$ is a permutation of the binary labels used to internally represent functional states. This implies $\Phi$ is sensitive to functionally arbitrary aspects of a particular labeling scheme, with no clear justification in terms of phenomenological differences. In light of this, we argue any quantitative theory of consciousness, including IIT, should be invariant under isomorphisms if it is to avoid the existence of isomorphic philosophical zombies and the epistemological problems they pose.Comment: 13 page

Basic Cable: Notes Toward Digital Ontology

This thesis begins the work of constructing a fundamental ontology that employs the network automaton—a class of abstract computer program—as its model. Following a brief historical overview of the theory of network automata and its culmination in the work of Steven Wolfram, I examine how it bears on the ancient question concerning whether the continuous or the discrete has ontological primacy, consider the ontological status of materiality in consultation with Deleuzean ontology, and introduce the concept of prescience as a means of topologically mapping emergent patterns within the causal relations that compose the network. Finally, I will break the network automaton down even further into its most rudimentary functional operations, and consider preliminarily how this model might be adapted toward an atomistic theory of the subject