424 research outputs found
Modelling Garbage Collection Algorithms --- Extend abstract
We show how abstract requirements of garbage collection can be captured using temporal logic. The temporal logic specification can then be used as a basis for process algebra specifications which can involve varying amounts of parallelism. We present two simple CCS specifications as an example, followed by a more complex specification of the cyclic reference counting algorithm. The verification of such algorithms is then briefly discussed
A Survey on IT-Techniques for a Dynamic Emergency Management in Large Infrastructures
This deliverable is a survey on the IT techniques that are relevant to the three use cases of the project EMILI. It describes the state-of-the-art in four complementary IT areas: Data cleansing, supervisory control and data acquisition, wireless sensor networks and complex event processing. Even though the deliverable’s authors have tried to avoid a too technical language and have tried to explain every concept referred to, the deliverable might seem rather technical to readers so far little familiar with the techniques it describes
Discovering Physical Interaction Vulnerabilities in IoT Deployments
Internet of Things (IoT) applications drive the behavior of IoT deployments
according to installed sensors and actuators. It has recently been shown that
IoT deployments are vulnerable to physical interactions, caused by design flaws
or malicious intent, that can have severe physical consequences. Yet, extant
approaches to securing IoT do not translate the app source code into its
physical behavior to evaluate physical interactions. Thus, IoT consumers and
markets do not possess the capability to assess the safety and security risks
these interactions present. In this paper, we introduce the IoTSeer security
service for IoT deployments, which uncovers undesired states caused by physical
interactions. IoTSeer operates in four phases (1) translation of each actuation
command and sensor event in an app source code into a hybrid I/O automaton that
defines an app's physical behavior, (2) combining apps in a novel composite
automaton that represents the joint physical behavior of interacting apps, (3)
applying grid-based testing and falsification to validate whether an IoT
deployment conforms to desired physical interaction policies, and (4)
identification of the root cause of policy violations and proposing patches
that guide users to prevent them. We use IoTSeer in an actual house with 13
actuators and six sensors with 37 apps and demonstrate its effectiveness and
performance
State-of-the-art on evolution and reactivity
This report starts by, in Chapter 1, outlining aspects of querying and updating resources on
the Web and on the Semantic Web, including the development of query and update languages
to be carried out within the Rewerse project.
From this outline, it becomes clear that several existing research areas and topics are of
interest for this work in Rewerse. In the remainder of this report we further present state of
the art surveys in a selection of such areas and topics. More precisely: in Chapter 2 we give
an overview of logics for reasoning about state change and updates; Chapter 3 is devoted to briefly describing existing update languages for the Web, and also for updating logic programs;
in Chapter 4 event-condition-action rules, both in the context of active database systems and
in the context of semistructured data, are surveyed; in Chapter 5 we give an overview of some relevant rule-based agents frameworks
Specification-driven design of custom hardware in HOP
technical reportWe present a language "Hardware viewed as Objects and Processes" (HOP) for specifying the structure, behavior, and timing of hardware systems. HOP embodies a simple process model for lock-step synchronous processes. Processes may be described both as a black-box and as a collection of interacting sub-processes. The latter can be statically simplified using an algorithm 'PARCOMP'. PARCOMP symbolically simulates a collection of interacting processes. The advantages claimed for HOP include simple semantics, intuitiveness, high expressive power, and numerous provisions to support easily verifiable designs all the way to VLSI layout. After introducing HOP, and presenting some of the results obtained from experimenting with the HOP design system, we present the design of a large hardware system (the "Utah Simulation Engine") currently being developed to speed-up distributed discrete event simulation using Time Warp. Issues in the specification driven design of this system are discussed and illustrated using HOP
A VISUAL DESIGN METHOD AND ITS APPLICATION TO HIGH RELIABILITY HYPERMEDIA SYSTEMS
This work addresses the problem of the production of hypermedia
documentation for applications that require high reliability, particularly
technical documentation in safety critical industries. One requirement of this
application area is for the availability of a task-based organisation, which
can guide and monitor such activities as maintenance and repair. In safety
critical applications there must be some guarantee that such sequences are
correctly presented. Conventional structuring and design methods for
hypermedia systems do not allow such guarantees to be made. A formal
design method that is based on a process algebra is proposed as a solution
to this problem. Design methods of this kind need to be accessible to
information designers. This is achieved by use of a technique already
familiar to them: the storyboard. By development of a storyboard notation
that is syntactically equivalent to a process algebra a bridge is made
between information design and computer science, allowing formal analysis
and refinement of the specification drafted by information designers.
Process algebras produce imperative structures that do not map easily into
the declarative formats used for some hypermedia systems, but can be
translated into concurrent programs. This translation process, into a
language developed by the author, called ClassiC, is illustrated and the
properties that make ClassiC a suitable implementation target discussed.
Other possible implementation targets are evaluated, and a comparative
illustration given of translation into another likely target, Java
Verification of Branching-Time and Alternating-Time Properties for Exogenous Coordination Models
Information and communication systems enter an increasing number of areas of daily lives. Our reliance and dependence on the functioning of such systems is rapidly growing together with the costs and the impact of system failures. At the same time the complexity of hardware and software systems extends to new limits as modern hardware architectures become more and more parallel, dynamic and heterogenous. These trends demand for a closer integration of formal methods and system engineering to show the correctness of complex systems within the design phase of large projects.
The goal of this thesis is to introduce a formal holistic approach for modeling, analysis and synthesis of parallel systems that potentially addresses complex system behavior at any layer of the hardware/software stack. Due to the complexity of modern hardware and software systems, we aim to have a hierarchical modeling framework that allows to specify the behavior of a parallel system at various levels of abstraction and that facilitates designing complex systems in an iterative refinement procedure, in which more detailed behavior is added successively to the system description. In this context, the major challenge is to provide modeling formalisms that are expressive enough to address all of the above issues and are at the same time amenable to the application of formal methods for proving that the system behavior conforms to its specification. In particular, we are interested in specification formalisms that allow to apply formal verification techniques such that the underlying model checking problems are still decidable within reasonable time and space bounds.
The presented work relies on an exogenous modeling approach that allows a clear separation of coordination and computation and provides an operational semantic model where formal methods such as model checking are well suited and applicable. The channel-based exogenous coordination language Reo is used as modeling formalism as it supports hierarchical modeling in an iterative top-down refinement procedure. It facilitates reusability, exchangeability, and heterogeneity of components and forms the basis to apply formal verification methods. At the same time Reo has a clear formal semantics based on automata, which serve as foundation to apply formal methods such as model checking.
In this thesis new modeling languages are presented that allow specifying complex systems in terms of Reo and automata models which yield the basis for a holistic approach on modeling, verification and synthesis of parallel systems. The second main contribution of this thesis are tailored branching-time and alternating time temporal logics as well as corresponding model checking algorithms. The thesis includes results on the theoretical complexity of the underlying model checking problems as well as practical results. For the latter the presented approach has been implemented in the symbolic verification tool set Vereofy. The implementation within Vereofy and evaluation of the branching-time and alternating-time model checker is the third main contribution of this thesis
Reversible Computation: Extending Horizons of Computing
This open access State-of-the-Art Survey presents the main recent scientific outcomes in the area of reversible computation, focusing on those that have emerged during COST Action IC1405 "Reversible Computation - Extending Horizons of Computing", a European research network that operated from May 2015 to April 2019. Reversible computation is a new paradigm that extends the traditional forwards-only mode of computation with the ability to execute in reverse, so that computation can run backwards as easily and naturally as forwards. It aims to deliver novel computing devices and software, and to enhance existing systems by equipping them with reversibility. There are many potential applications of reversible computation, including languages and software tools for reliable and recovery-oriented distributed systems and revolutionary reversible logic gates and circuits, but they can only be realized and have lasting effect if conceptual and firm theoretical foundations are established first
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