20,171 research outputs found
Runtime verification for biochemical programs
The biochemical paradigm is well-suited for modelling autonomous systems and new programming languages are emerging from this approach. However, in order to validate such programs, we need to define precisely their semantics and to provide verification techniques. In this paper, we consider a higher-order biochemical calculus that models the structure of system states and its dynamics thanks to rewriting abstractions, namely rules and strategies. We extend this calculus with a runtime verification technique in order to perform automatic discovery of property satisfaction failure. The property specification language is a subclass of LTL safety and liveness properties
The SATIN component system - a metamodel for engineering adaptable mobile systems
Mobile computing devices, such as personal digital assistants and mobile phones, are becoming increasingly popular, smaller, and more capable. We argue that mobile systems should be able to adapt to changing requirements and execution environments. Adaptation requires the ability-to reconfigure the deployed code base on a mobile device. Such reconfiguration is considerably simplified if mobile applications are component-oriented rather than monolithic blocks of code. We present the SATIN (system adaptation targeting integrated networks) component metamodel, a lightweight local component metamodel that offers the flexible use of logical mobility primitives to reconfigure the software system by dynamically transferring code. The metamodel is implemented in the SATIN middleware system, a component-based mobile computing middleware that uses the mobility primitives defined in the metamodel to reconfigure both itself and applications that it hosts. We demonstrate the suitability of SATIN in terms of lightweightedness, flexibility, and reusability for the creation of adaptable mobile systems by using it to implement, port, and evaluate a number of existing and new applications, including an active network platform developed for satellite communication at the European space agency. These applications exhibit different aspects of adaptation and demonstrate the flexibility of the approach and the advantages gaine
The 1990 progress report and future plans
This document describes the progress and plans of the Artificial Intelligence Research Branch (RIA) at ARC in 1990. Activities span a range from basic scientific research to engineering development and to fielded NASA applications, particularly those applications that are enabled by basic research carried out at RIA. Work is conducted in-house and through collaborative partners in academia and industry. Our major focus is on a limited number of research themes with a dual commitment to technical excellence and proven applicability to NASA short, medium, and long-term problems. RIA acts as the Agency's lead organization for research aspects of artificial intelligence, working closely with a second research laboratory at JPL and AI applications groups at all NASA centers
Organization of Multi-Agent Systems: An Overview
In complex, open, and heterogeneous environments, agents must be able to
reorganize towards the most appropriate organizations to adapt unpredictable
environment changes within Multi-Agent Systems (MAS). Types of reorganization
can be seen from two different levels. The individual agents level
(micro-level) in which an agent changes its behaviors and interactions with
other agents to adapt its local environment. And the organizational level
(macro-level) in which the whole system changes it structure by adding or
removing agents. This chapter is dedicated to overview different aspects of
what is called MAS Organization including its motivations, paradigms, models,
and techniques adopted for statically or dynamically organizing agents in MAS.Comment: 12 page
Agent Based Modeling and Simulation: An Informatics Perspective
The term computer simulation is related to the usage of a computational model in order to improve the understanding of a system's behavior and/or to evaluate strategies for its operation, in explanatory or predictive schemes. There are cases in which practical or ethical reasons make it impossible to realize direct observations: in these cases, the possibility of realizing 'in-machina' experiments may represent the only way to study, analyze and evaluate models of those realities. Different situations and systems are characterized by the presence of autonomous entities whose local behaviors (actions and interactions) determine the evolution of the overall system; agent-based models are particularly suited to support the definition of models of such systems, but also to support the design and implementation of simulators. Agent-Based models and Multi-Agent Systems (MAS) have been adopted to simulate very different kinds of complex systems, from the simulation of socio-economic systems to the elaboration of scenarios for logistics optimization, from biological systems to urban planning. This paper discusses the specific aspects of this approach to modeling and simulation from the perspective of Informatics, describing the typical elements of an agent-based simulation model and the relevant research.Multi-Agent Systems, Agent-Based Modeling and Simulation
Towards a Formal Model of Recursive Self-Reflection
Self-awareness holds the promise of better decision making based on a comprehensive assessment of a system\u27s own situation. Therefore it has been studied for more than ten years in a range of settings and applications. However, in the literature the term has been used in a variety of meanings and today there is no consensus on what features and properties it should include. In fact, researchers disagree on the relative benefits of a self-aware system compared to one that is very similar but lacks self-awareness.
We sketch a formal model, and thus a formal definition, of self-awareness. The model is based on dynamic dataflow semantics and includes self-assessment, a simulation and an abstraction as facilitating techniques, which are modeled by spawning new dataflow actors in the system. Most importantly, it has a method to focus on any of its parts to make it a subject of analysis by applying abstraction, self-assessment and simulation. In particular, it can apply this process to itself, which we call recursive self-reflection. There is no arbitrary limit to this self-scrutiny except resource constraints
Supporting Management lnteraction and Composition of Self-Managed Cells
Management in ubiquitous systems cannot rely on human intervention or centralised
decision-making functions because systems are complex and devices
are inherently mobile and cannot refer to centralised management applications
for reconfiguration and adaptation directives. Management must be devolved,
based on local decision-making and feedback control-loops embedded in autonomous
components. Previous work has introduced a Self-Managed Cell (SMC)
as an infrastructure for building ubiquitous applications. An SMC consists
of a set of hardware and software components that implement a policy-driven
feedback control-loop. This allows SMCs to adapt continually to changes in
their environment or in their usage requirements. Typical applications include
body-area networks for healthcare monitoring, and communities of unmanned
autonomous vehicles (UAVs) for surveillance and reconnaissance operations.
Ubiquitous applications are typically formed from multiple interacting autonomous
components, which establish peer-to-peer collaborations, federate and
compose into larger structures. Components must interact to distribute management
tasks and to enforce communication strategies. This thesis presents
an integrated framework which supports the design and the rapid establishment
of policy-based SMC interactions by systematically composing simpler abstractions
as building elements of a more complex collaboration. Policy-based
interactions are realised – subject to an extensible set of security functions –
through the exchanges of interfaces, policies and events, and our framework
was designed to support the specification, instantiation and reuse of patterns of
interaction that prescribe the manner in which these exchanges are achieved.
We have defined a library of patterns that provide reusable abstractions for
the structure, task-allocation and communication aspects of an interaction,
which can be individually combined for building larger policy-based systems in
a methodical manner. We have specified a formal model to ensure the rigorous
verification of SMC interactions before policies are deployed in physical devices.
A prototype has been implemented that demonstrates the practical feasibility
of our framework in constrained resources
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