Formal Modeling and Analysis of Timed Systems

To cope with large data sets, distributed data stores partition their data across servers. However, real-world systems usually do not provide useful transactional semantics for operations accessing multiple partitions due to the delays involved in achieving multi-partition consistency. Read Atomic Multi-Partition (RAMP) transactions have recently been proposed as efficient light-weight multi-partition transactions that guarantee read atomicity: either all updates or no updates of a transaction are visible to other transactions. In this paper we formalize RAMP transactions in rewriting logic and perform model checking verification of key properties using the Maude tool. In particular, we develop detailed formal models---and formally analyze---a number of extensions and optimizations of RAMP that are only briefly mentioned by the RAMP developers.

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.

FORMAL FAILURE MODELS

Formal Modeling and Analysis of Timed Systems

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.

The paper examined the problem of modeling and design of software computer systems. The article briefly describes the content aspects of the various stages of the implementation of software complexes and systems. The methodology of research and analysis of systems, which uses the method of computer simulation modeling, is given. The aim of the work is to create a new universal approach to the design and implementation of software systems of various levels of complexity. During the study, the following general scientific methods were used: system analysis, synthesis, formalization, modeling, decomposition, structuring, description, comparison. The materials used in the study were: computers and software development tools. As a result of the study proposed a universal agent-module approach to the design and implementation of software systems based on simulation agent-based modeling. The study presents the processes of modeling and designing software systems, their stages, and the possibility of their integration within the described approach. Examples of formal model and structure of the software system under design based on the agent-module approach are presented. The proposed approach can be used in the process of software development at the initial stages related to modeling and designing of software systems. Integration of modeling and design stages in the proposed approach will significantly reduce software development time and simplify the design process by making it clearer and more formalized. Materials of the article are of scientific and practical value for a wide range of specialists interested in system analysis, modeling, design and implementation of software systems.

A model checker is an automatic tool that traverses a specific structure (normally a Kripke structure referred as the modelM) to check the satisfaction of some (temporal) logical propertyf. This is formally stated asM⊧f. For some formal notations, the modelMof a specificationS(written in a formal languageL) can be described as a labelled transition system (LTS). Specifically, it is not clear in general how usual tools such as SPIN, FDR, PAT, etc., create the LTS representation from a given process. Although one expects the coherence of the LTS generation with the semantics ofL, it is completely hidden inside the model checker itself. In this paper we show how to create a model checker forL, using a development approach based on its operational semantics. We use a systematic semantics embedding and the formal modeling using logic programming and analysis (FORMULA) framework to this end. We illustrate our strategy considering the formal language COMPASS modelling language (CML)—a new language that was based on CSP, VDM and the refinement calculus proposed for modelling and analysis of systems of systems. As FORMULA is based on satisfiability modulo theories solving, our model checker can handle communications and predicates involving data with infinite domains by building and manipulating a symbolic LTS. This goes beyond the capabilities of traditional CSP model checkers such as FDR and PAT. Moreover, we show how to reduce time and space complexities by simple semantic modifications in the embedding. This allows a more semantics-preserving tuning. Finally, we show a real implementation of our model checker in an integrated development platform for CML and its practical use on an industrial case study.

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

A framework for mapping and comparing behavioural theories in models of social-ecological 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.

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.

A formal model and analysis of an IoT protocol

In spite of it being necessary for humans to consider modeling, analysis, and control of human-included systems, it has been considered a challenging problem because of the critical role of humans in complex systems and of humans' capability of executing unanticipated actions–both beneficial and detrimental ones. Thus, to provide systematic approaches to modeling human actions as a part of system behaviors, a formal modeling framework for human-involved systems in which humans play a controlling role based on their perceptual information is presented. The theory of affordance provides definitions of human actions and their associated properties; Finite State Automata (FSA) based modeling is capable of mapping nondeterministic humans into computable components in the system representation. In this talk, we investigate the role of perception in human actions in the system operation and examine the representation of perceptual elements in affordance-based modeling formalism. The proposed framework is expecte...

The modelling and analysis of Flexible Manufacturing Systems (FMS) has been approached through a variety of methodologies, which diverge considerably in their ability to represent and analyse complex FMS features. This paper broadly classifies the chief approaches, and evaluates them against certain prescriptions. Petri Nets and their extensions score highly on the evaluation criteria. A modelling approach is presented based on Conditional Predicate/Transition Nets (CPrTN), which extend the modelling power of Predicate/Transition Nets. CPrTN provide formal, concise and graphical models, eminently suited for modelling the often complex dynamic interactions in an FMS.

A fundamental understanding of algorithmic bioprocesses is key to learning how information processing occurs in nature at the cell level. The field is concerned with the interactions between computer science on the one hand and biology, chemistry, and DNA-oriented nanoscience on the other. In particular, this book offers a comprehensive overview of research into algorithmic self-assembly, RNA folding, the algorithmic foundations for biochemical reactions, and the algorithmic nature of developmental processes. The editors of the book invited 36 chapters, written by the leading researchers in this area, and their contributions include detailed tutorials on the main topics, surveys of the state of the art in research, experimental results, and discussions of specific research goals. The main subjects addressed are sequence discovery, generation, and analysis; nanoconstructions and self-assembly; membrane computing; formal models and analysis; process calculi and automata; biochemical reactions; and other topics from natural computing, including molecular evolution, regulation of gene expression, light-based computing, cellular automata, realistic modelling of biological systems, and evolutionary computing. This subject is inherently interdisciplinary, and this book will be of value to researchers in computer science and biology who study the impact of the exciting mutual interaction between our understanding of bioprocesses and our understanding of computation.