Formal modeling and analysis of RAMP transaction systems

FORMAL FAILURE MODELS

Formal Modeling and Analysis of Timed Systems

This volume contains the proceedings of the 4th International Conference on Formal Modelling and Analysis of Timed Systems (FORMATS 2006), held in Paris (France) on September 25-27, 2006. The aim of FORMATS is to promote the study of fundamental and practical aspects of timed systems, and to bring together researchers from different disciplines that share interests in modelling and analysis of timed systems.

In this paper we revisit the topic of dialogue grammars at the illocutionary force level and present a new approach to the formal modelling, evaluation and comparison of these models based on recursive transition networks. Through the use of appropriate tools such finite-state grammars can be formally analysed and validated against empirically collected corpora. To illustrate our approach we show: (a) the construction of human-human dialogue grammars on the basis of recently collected natural language dialogues in joint-task situations; and (b) the evaluation and comparison of these dialogue grammars using formal methods. This work provides a novel basis for developing and evaluating dialogue grammars as well as for engineering corpus-tailored dialogue managers which can be verified for adequacy.KeywordsDialogue SystemDialogue ModelDialogue ManagementDialogue StructureDialogue ParticipantThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

This paper describes the application of Real-Time Maude to the formal modeling, simulation, and model checking analysis of the NORM multicast protocol standard being developed by the Internet Engineering Task Force. Because of its size and sophistication, real-time features, and the need to model and analyze subcomponents of NORM both in isolation and in combination, NORM poses a set of challenging problems for its formal specification and analysis. Our formal modeling and analysis efforts made us aware of ambiguities, inconsistencies, and cases of under-specification in the informal specification of NORM. Our work indicates that formal methods can successfully be applied by non-experts during the development of advanced Internet protocol standards.

Formal security analysis of LoRaWAN

This paper describes the application of the Real-Time Maude tool to the formal specification and analysis of the CASH scheduling algorithm and its suggested modifications. The CASH algorithm is a sophisticated state-of-the-art scheduling algorithm with advanced capacity sharing features for reusing unused execution budgets. Because the number of elements in the queue of unused resources can grow beyond any bound, the CASH algorithm poses challenges to its formal specification and analysis. Real-Time Maude extends the rewriting logic tool Maude to support formal specification and analysis of object-based real-time systems. It emphasizes generality of specification and supports a spectrum of analysis methods, including symbolic simulation and (unbounded and time-bounded) reachability analysis and LTL model checking. We show how we have used Real-Time Maude to experiment with different design modifications of the CASH algorithm using both Monte Carlo simulation and reachability analysis. We could quickly and easily specify and analyze these modifications using Real-Time Maude, and discovered subtle behaviors in the modifications that lead to missed deadlines.KeywordsModel CheckReachability AnalysisSpare CapacityFormal SimulationRelative DeadlineThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Formal Modeling and Analysis of Timed Systems

This paper is related to dissemination and exploitation of the InFoCPS PhD research project: Failure of Cyber-Physical Systems (CPS) may cause extensive damage. Safety standards emphasize the use of formal analysis in CPS development processes. Performance degradation assessment and estimation of lifetime of energy storage (electric batteries) are vital in supporting maintenance decisions and guaranteeing CPS reliability. Existing formal analysis techniques mainly focus on specifying energy constraints in simplified manners and checking whether systems operate within given energy bounds. Leading to overlooked energy features that impede development of trustworthy CPS. Prognostics and health management (PHM) estimate energy uncertainty and predict remaining life of systems. We aim to utilize PHM techniques to rigorously model dynamic energy behaviors; resulting models are amenable to formal analysis. This project will increase the degree of maintenance of CPS while (non)-functional requirements are preserved correctly.

BackgroundBrain, heart and skeletal muscle share similar properties of excitable tissue, featuring both discrete behavior (all-or-nothing response to electrical activation) and continuous behavior (recovery to rest follows a temporal path, determined by multiple competing ion flows). Classical mathematical models of excitable cells involve complex systems of nonlinear differential equations. Such models not only impair formal analysis but also impose high computational demands on simulations, especially in large-scale 2-D and 3-D cell networks. In this paper, we show that by choosing Hybrid Automata as the modeling formalism, it is possible to construct a more abstract model of excitable cells that preserves the properties of interest while reducing the computational effort, thereby admitting the possibility of formal analysis and efficient simulation.ResultsWe have developed CellExcite, a sophisticated simulation environment for excitable-cell networks. CellExcite allows the user to sketch a tissue of excitable cells, plan the stimuli to be applied during simulation, and customize the diffusion model. CellExcite adopts Hybrid Automata (HA) as the computational model in order to efficiently capture both discrete and continuous excitable-cell behavior.ConclusionsThe CellExcite simulation framework for multicellular HA arrays exhibits significantly improved computational efficiency in large-scale simulations, thus opening the possibility for formal analysis based on HA theory. A demo of CellExcite is available at .

Formal Techniques, Modelling and Analysis of Timed and Fault-Tolerant Systems

Formal Concept Analysis is an unsupervised machine learning technique that has successfully been applied to document organisation by considering documents as objects and keywords as attributes. The basic algorithms of Formal Concept Analysis then allow an intelligent information retrieval system to cluster documents according to keyword views. This paper investigates the scalability of this idea. In particular we present the results of applying spatial data structures to large datasets in formal concept analysis. Our experiments are motivated by the application of the Formal Concept Analysis idea of a virtual filesystem [11,17,15]. In particular the libferris [1] Semantic File System. This paper presents customizations to an RD-Tree Generalized Index Search Tree based index structure to better support the application of Formal Concept Analysis to large data sources.

Objective of this contribution is to present the use of Model-based Systems Engineering within the engineering design community. Based on a differentiation between SE and MBSE, the definition of three core MBSE elements, namely modelling method, modelling language, and modelling tool as well as the three major aspects of a consistent system model (requirements, behaviour, and structure) a structured review is conducted, focussing on the understanding and motivation as well as the modelling of systems. The review includes 93 publications from Design Society library and proceedings of the CIRP Design conferences during the period from 2011 to 2022. The review points out, that there is an increasing application of MBSE within the engineering design community, mainly focussing on architecture definition or combined engineering activities. Only a small portion of works (16 publications) are providing a consistent approach as these publications link all aspects of the system model and consider all three MBSE elements. It can be concluded, that there is a diffuse understanding of MBSE and different motivations are given to apply more formal system models as well as modelling tools.

Formal analyses using human mental models have been effective in identifying how automation behavior can cause mode confusion and associated human error. However, state-machine-based mental model formalisms are unrealistically precise. To address this, we introduce Fuzzy Mental Models (FMMs). FMMs combine state machines with fuzzy logic to precisely represent vagueness in mental models. We define how FMMs integrate into larger formal system models, where the state of the automation and FMM co-evolve. We identify patterns within a system model that indicate mode confusion. These include new conditions that emerge only through the vagueness captured by FMMs. We also present a model-based analysis capable of discovering the mode confusion patterns in system models containing FMMs. Our approach is demonstrated with two realistic case studies: a modern automobile gear shifter and a cloud storage file system. We conclude by discussing the implications of our contributions and directions for future research.

We present a formal model of the MQ Telemetry Transport version 3.1 protocol based on a timed message-passing process algebra. We explain the modeling choices that we made, including pointing out ambiguities in the original protocol specification, and we carry out a static analysis of the formal protocol model, which is based on an approximation of a name-substitution semantics for algebra. The analysis reveals that the protocol behaves correctly as specified against the first two quality of service modes of operation providing at most once and at least once delivery semantics to the subscribers. However, we find that the third and highest quality of service semantics is prone to error and at best ambiguous in certain aspects of its specification. Finally, we suggest an enhancement of this level of QoS for the protocol.