329 research outputs found
Weighted Modal Transition Systems
Specification theories as a tool in model-driven development processes of
component-based software systems have recently attracted a considerable
attention. Current specification theories are however qualitative in nature,
and therefore fragile in the sense that the inevitable approximation of systems
by models, combined with the fundamental unpredictability of hardware
platforms, makes it difficult to transfer conclusions about the behavior, based
on models, to the actual system. Hence this approach is arguably unsuited for
modern software systems. We propose here the first specification theory which
allows to capture quantitative aspects during the refinement and implementation
process, thus leveraging the problems of the qualitative setting.
Our proposed quantitative specification framework uses weighted modal
transition systems as a formal model of specifications. These are labeled
transition systems with the additional feature that they can model optional
behavior which may or may not be implemented by the system. Satisfaction and
refinement is lifted from the well-known qualitative to our quantitative
setting, by introducing a notion of distances between weighted modal transition
systems. We show that quantitative versions of parallel composition as well as
quotient (the dual to parallel composition) inherit the properties from the
Boolean setting.Comment: Submitted to Formal Methods in System Desig
A Few Considerations on Structural and Logical Composition in Specification Theories
Over the last 20 years a large number of automata-based specification
theories have been proposed for modeling of discrete,real-time and
probabilistic systems. We have observed a lot of shared algebraic structure
between these formalisms. In this short abstract, we collect results of our
work in progress on describing and systematizing the algebraic assumptions in
specification theories.Comment: In Proceedings FIT 2010, arXiv:1101.426
Statistical Model Checking of Dynamic Networks of Stochastic Hybrid Automata
In this paper we present a modelling formalism for dynamic networksof stochastic hybrid automata. In particular, our formalism is based on primitivesfor the dynamic creation and termination of hybrid automata components duringthe execution of a system. In this way we allow for natural modelling of conceptssuch as multiple threads found in various programming paradigms, as well as thedynamic evolution of biological systems.We provide a natural stochastic semantics of the modelling formalism based on re-peated output races between the dynamic evolving components of a system. Asspecification language we present a quantified extension of the logic Metric Tempo-ral Logic (MTL). As a main contribution of this paper, the statistical model checkingengine of U PPAAL has been extended to the setting of dynamic networks of hybridsystems and quantified MTL. We demonstrate the usefulness of the extended for-malisms in an analysis of a dynamic version of the well-known Train Gate example,as well as in natural monitoring of a MTL formula, where observations may lead todynamic creation of monitors for sub-formulas
Low-Profile Compact Dual-Band Unit Cell for Polarizing Surfaces Operating in Orthogonal Polarizations
Experimental Biological Protocols with Formal Semantics
Both experimental and computational biology is becoming increasingly
automated. Laboratory experiments are now performed automatically on
high-throughput machinery, while computational models are synthesized or
inferred automatically from data. However, integration between automated tasks
in the process of biological discovery is still lacking, largely due to
incompatible or missing formal representations. While theories are expressed
formally as computational models, existing languages for encoding and
automating experimental protocols often lack formal semantics. This makes it
challenging to extract novel understanding by identifying when theory and
experimental evidence disagree due to errors in the models or the protocols
used to validate them. To address this, we formalize the syntax of a core
protocol language, which provides a unified description for the models of
biochemical systems being experimented on, together with the discrete events
representing the liquid-handling steps of biological protocols. We present both
a deterministic and a stochastic semantics to this language, both defined in
terms of hybrid processes. In particular, the stochastic semantics captures
uncertainties in equipment tolerances, making it a suitable tool for both
experimental and computational biologists. We illustrate how the proposed
protocol language can be used for automated verification and synthesis of
laboratory experiments on case studies from the fields of chemistry and
molecular programming
Timed I/O Automata: It is never too late to complete your timed specification theory
A specification theory combines notions of specifications and implementations
with a satisfaction relation, a refinement relation and a set of operators
supporting stepwise design. We develop a complete specification framework for
real-time systems using Timed I/O Automata as the specification formalism, with
the semantics expressed in terms of Timed I/O Transition Systems. We provide
constructs for refinement, consistency checking, logical and structural
composition, and quotient of specifications -- all indispensable ingredients of
a compositional design methodology. The theory is backed by rigorous proofs and
is being implemented in the open-source tool ECDAR.Comment: Version submitted for revie
An Inverse Method for Policy-Iteration Based Algorithms
We present an extension of two policy-iteration based algorithms on weighted
graphs (viz., Markov Decision Problems and Max-Plus Algebras). This extension
allows us to solve the following inverse problem: considering the weights of
the graph to be unknown constants or parameters, we suppose that a reference
instantiation of those weights is given, and we aim at computing a constraint
on the parameters under which an optimal policy for the reference instantiation
is still optimal. The original algorithm is thus guaranteed to behave well
around the reference instantiation, which provides us with some criteria of
robustness. We present an application of both methods to simple examples. A
prototype implementation has been done
Computing Nash Equilibrium in Wireless Ad Hoc Networks: A Simulation-Based Approach
This paper studies the problem of computing Nash equilibrium in wireless
networks modeled by Weighted Timed Automata. Such formalism comes together with
a logic that can be used to describe complex features such as timed energy
constraints. Our contribution is a method for solving this problem using
Statistical Model Checking. The method has been implemented in UPPAAL model
checker and has been applied to the analysis of Aloha CSMA/CD and IEEE 802.15.4
CSMA/CA protocols.Comment: In Proceedings IWIGP 2012, arXiv:1202.422
Optimisation by unit-cell rotation of linear-to-circular polarising reflectors for practical primary feeds
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