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The paper deals with conformance testing based on formal specications. The con- cept of safe testing was earlier proposed by the authors for trace based conformance. This concept is propagated on the case of (weak) simulation based on a relation between specication and implementation states. The theory of safe simulation of systems with refusals and destructions is proposed. The problems of complete testing and sucient conditions for the existense of complete test suite are discussed. The practical algo- rithm of complete testing for restricted classes of specications and implementations is described.

Many researchers have explored the relationship between recurrent neural networks and finite state machines. Finite state machines constitute the best-characterized computational model, whereas artificial neural networks have become a very successful tool for modeling and problem solving. The neurally-inspired lateral inhibition method, and its application to motion detection tasks, have been successfully implemented in recent years. In this paper, control knowledge of the algorithmic lateral inhibition (ALI) method is described and applied by means of finite state machines, in which the state space is constituted from the set of distinguishable cases of accumulated charge in a local memory. The article describes an ALI implementation for a motion detection task. For the implementation, we have chosen to use one of the members of the 16-nm Kintex UltraScale+ family of Xilinx FPGAs. FPGAs provide the necessary accuracy, resolution, and precision to run neural algorithms alongside current sensor technologies. The results offered in this paper demonstrate that this implementation provides accurate object tracking performance on several datasets, obtaining a high F-score value (0.86) for the most complex sequence used. Moreover, it outperforms implementations of a complete ALI algorithm and a simplified version of the ALI algorithm—named “accumulative computation”—which was run about ten years ago, now reaching real-time processing times that were simply not achievable at that time for ALI.

In some regions of natural resource extraction, embedded local populations receive transfers that compensate them for environmental consequences of extraction; while in others, these populations receive no benefits and endure negative environmental externalities, which can lead to violent protest. This article develops a formal model of the strategic dynamics among a government, a natural resource extraction firm, and a local population in an extractive region to understand the variation in extractive outcomes. The model specifies the conditions under which firms will provide promised transfers to a local population, distributive conflict will occur, and how the government will respond. [ABSTRACT FROM AUTHOR]

Nowadays, novel architectures like Cloud and Internet of Things (IoT) make available several resources like computing nodes, environmental sensors etc. that enable the introduction of more and more intelligent systems able to face complex situations. In particular management of critical and dangerous situations may take advantage of those systems whose complexity is growing up faster and faster. In this scenario, it is difficult to orchestrate different autonomous systems in order to face with new, previously unmanaged emergencies. In this work we present a modeling methodology and a planning techniques based on a multi-agent model. Agents describe capabilities of each available IoT element in an area where a critical situation has occurred; the planning methodology exploit both classical and a new counter-example based approaches to build a coordination plan of resources in order to achieve given goals like traffic management or people flight during a terrorist attack. [ABSTRACT FROM AUTHOR]

Social network users expect the social networks that they use to preserve their privacy. Traditionally, privacy breaches have been understood as the malfunctioning of a given system. However, in online social networks, privacy breaches are not necessarily a malfunctioning of a system but a byproduct of its workings. The users are allowed to create and share content about themselves and others. When multiple entities start distributing content without a control, information can reach unintended individuals and inference can reveal more information about the user. Accordingly, this paper first categorizes the privacy violations that take place in online social networks. Our categorization yields that the privacy violations in online social networks stem from intricate interactions and detecting these violations requires semantic understanding of events. Our proposed approach is based on agent-based representation of a social network, where the agents manage users’ privacy requirements by creating commitments with the system. The privacy context, including the relations among users or content types, are captured using description logic. The proposed detection algorithm performs reasoning using the description logic and commitments on a varying depths of social networks. We implement the proposed model and evaluate our approach using real-life social networks. [ABSTRACT FROM PUBLISHER]

The traditional hazard analysis approaches applied to the socio-technical system cannot cover the complex organization structures, the interactions between systems and human behaviors, the interrelated factors among sub-systems and the safety culture of specific societies. This paper presents an integrated hazard identification approach named System-Theoretic Process Analysis Based on Formalization Model (BFM-STPA), which can solve the above issues. Firstly, the hierarchical control structure models of the socio-technical system are established through Colored Petri Nets (CPN) due to its strong description ability and executable ability, which may also be regarded as the graphical system specification. Secondly, the hazards can be identified according to the CPN models following a series of guide conditions. Thirdly, the comprehensive contributing factors to the hazards will be found out by tracing the former states within the reachability graph generated from CPN model. Finally, an integrated hazard log can be derived for further hazard analysis and safety-guided design. In this paper, the above method was applied in the Chinese Train Control System level 3 (CTCS-3). And the process of hazard identification for the scenario of Temporary Speed Restriction issued was elaborated in detail. Compared with the hazard log generated by Hazard and Operability (HAZOP), the hazard log generated by BFM-STPA covered not only the subsystem failures, but also the deviation of interactions among subsystems from design intent, human errors and socio-technical drawbacks related to the TSR Issued scenario of CTCS-3. [ABSTRACT FROM AUTHOR]

At the very beginning of system development, typically only natural-language requirements are documented. As an informal source of information, however, natural-language specifications may be ambiguous and incomplete; this can be hard to detect by means of manual inspection. In this work, we present a formal model, named data-flow reactive system (DFRS), which can be automatically obtained from natural-language requirements that describe functional, reactive and temporal properties. A DFRS can also be used to assess whether the requirements are consistent and complete. We define two variations of DFRS: a symbolic and an expanded version. A symbolic DFRS (s-DFRS) is a concise representation that inherently avoids an explicit representation of (possibly infinite) sets of states and, thus, the state space-explosion problem. We use s-DFRS as part of a technique for test-case generation from natural-language requirements. In our approach, an expanded DFRS (e-DFRS) is built dynamically from a symbolic one, possibly limited to some bound; in this way, bounded analysis (e.g., reachability, determinism, completeness) can be performed. We adopt the s-DFRS as an intermediary representation from which models, for instance, SCR and CSP, are obtained for the purpose of test generation. An e-DFRS can also be viewed as the semantics of the s-DFRS from which it is generated. In order to connect such a semantic representation to established ones in the literature, we show that an e-DFRS can be encoded as a TIOTS: an alternative timed model based on the widely used IOLTS and ioco. To validate our overall approach, we consider two toy examples and two examples from the aerospace and automotive industry. Test cases are independently created and we verify that they are all compatible with the corresponding e-DFRS models generated from symbolic ones. This verification is performed mechanically with the aid of the NAT2TEST tool, which supports the manipulation of such models. [ABSTRACT FROM AUTHOR]

The passage of the Data Transparency and Accountability Act in the United States Congress will necessitate that government agencies provide more data in transparent formats. The issue of how to interpret such data remains an open question. The accounting profession has continued to struggle with common formats since the inception of balance sheets and income statements. The original FASB Conceptual Framework was developed to help construct consistent GAAP standards. XBRL was developed to provide a consistent representation of the data contained in financial statements and other financial documents. This research explores the use of two codifications (U.S. GAAP and IFRS) of GAAP standards in both their syntactic representation through XBRL taxonomies and their semantics through their authoritative references back to their own standards and codification. The research uses language theory to model the codifications in terms of the strings used to represent lexical content in the financial statements and to provide a systematic mapping to the semantics of the related XBRL specifications. The immediate objectives of this research are to provide a means to compare the semantic richness of U.S. GAAP and IFRS and to determine the consistency of either standardization with respect to the emerging shared Conceptual Framework. Ultimately, to the extent that the system is able to model both the syntax and the semantics of the financial statements, it could provide a baseline on which to consider assurance over parts of the financial statements, rather than over the financial statements taken as a whole. [ABSTRACT FROM AUTHOR]

Teams are ubiquitous in contemporary business, government, health care, and education settings; hence, the process of team formation is worth close examination. We propose models based in expectation states theory for the probability that a particular candidate (or subset of candidates) is selected from a pool of potential team members who are differentiated along diffuse status characteristics. The candidates may be equally qualified in other respects, but the ways in which they differ will be activated under specified conditions and influence their chances of selection. We use the “motherhood penalty” literature to illustrate the model and the inferences it affords. Our concluding discussion notes that although a step forward in understanding team selection, the model cannot be the whole story as “suitability,” a legitimate consideration in the team formation process, is unaddressed by an expectation states based model focused solely on attributions of competence as the drivers of teammate choice. [ABSTRACT FROM AUTHOR]

QoS-aware applications can satisfy not only the functional requirements of the customers, but also the QoS requirements. QoS-aware Web service orchestration translates the QoS requirements of the customers into those of its component Web services. In a system viewpoint, we discuss issues on QoS-aware Web service orchestration and design a typical QoS-aware Web service orchestration engine called QoS-WSOE. More importantly, we establish a formal model of QoS-WSOE based on actor systems theory. Within the formal model, we use a three-layered pyramidal structure to capture the requirements of the customers with a concept named QoS-aware WSO service, characteristics of QoS-WSOE with a concept named QoS-aware WSO system, and structures and behaviors of QoS-WSOE with a concept named QoS-aware WSO behavior. Conclusions showing that a system with QoS-aware WSO behavior is a QoS-aware WSO system and further can provide QoS-aware WSO Service are drawn. [ABSTRACT FROM PUBLISHER]

In this paper, a framework for a simulation approach to develop a formal representation of control and analysis of human-involved computer integrated manufacturing systems (Hi-CIM) is presented. Important properties of a human material handler within manufacturing systems are discussed and human tasks and errors are identified to build a simulation model. Based on the number of locations where a human operator is required to move to complete a task, material handling tasks are classified into two sets which include an on-the-spot task set and an around-the-system task set. For human errors associated with the task sets, a location error set and an orientation error set are defined. These task sets and error types provide a framework for developing a simulation model of a human material handling task-performing process. To represent the model, a colored Petri net model is used because it provides a good graphical and analytical representation of a system. Human tasks and error types are represented using color tokens. A simulation model of the system can be implemented based on the proposed colored Petri Net model.

In human machine systems, a user display should contain sufficient information to encapsulate expressive and normative human operator behavior. Failure in such system that is commanded by supervisor can be difficult to anticipate because of unexpected interactions between the different users and machines. Currently, most interfaces have non-deterministic choices at state of machine. Inspired by the theories of single user of an interface established on discrete event system, we present a formal model of multiple users, multiple machines, a supervisor and a supervisor machine. The syntax and semantics of these models are based on the system specification using timed automata that adheres to desirable specification properties conducive to solving the non-deterministic choices for usability properties of the supervisor and user interface. Further, the succinct interface developed by applying the weak bi-simulation relation, where large classes of potentially equivalent states are refined into a smaller one, enables the supervisor and user to perform specified task correctly. Finally, the proposed approach is applied to a model of a manufacturing system with several users interacting with their machines, a supervisor with several users and a supervisor with a supervisor machine to illustrate the design procedure of human–machine systems. The formal specification is validated by z-eves toolset.

A description has been provided for a formal model of cyber attack on virtualization tools that allow one to formulate condition for the security of virtualization tools. The concept of measuring the vulnerability of virtualization tools has been introduced that characterizes the predisposition of a system to vulnerabilities that contribute to the implementation of cyber attacks in the proposed formal model. These characteristics of virtualization tools allow one to compare different hypervisors and estimate the presence of vulnerabilities in them. [ABSTRACT FROM AUTHOR]

Societal transitions involve multiple actors, changes in institutions, values and technologies, and interactions across multiple sectors and scales. Given this complexity, this paper takes on the view that the societal transitions research field would benefit from the further maturation and broader uptake of modelling approaches. This paper shows how modelling can enhance the understanding of and support stakeholders to steer societal transitions. It discusses the benefits modelling provides for studying large societal systems and elaborates on different ways models can be used for transitions studies. Two model applications are presented in some detail to illustrate the benefits. Then, limitations of modelling societal transitions are discussed, which leads to an agenda for future activities: (1) better cooperation in the development of dynamic models, (2) stronger interaction with other transition scholars and stakeholders, and (3) use of additional modelling approaches that we think are relevant to and largely unexplored in transitions studies. [ABSTRACT FROM AUTHOR]

A central hypothesis about discrimination is that prejudice forces the stigmatized into low-paying, undesirable jobs. Prejudice clearly leads to exclusion. But surprisingly, evidence linking exclusion to disadvantage is mixed. We address this issue theoretically, providing a formal rational choice model combining arguments from sociology (on prejudice) and economics (on competition). Our theory suggests that economic organization is crucial. In economies dominated by monopoly, oligarchy, tradition, or government, prejudice may reduce some workers’ pay, and a disadvantageous secondary labor market may emerge. By contrast, in competitive free markets, exclusionary discrimination often occurs but does not reduce workers’ pay, nor does it induce a disadvantageous secondary labor market. Our theory suggests the conventional analytic approach to discrimination is misguided: Exclusion does not necessarily imply disadvantage; a shortfall in pay does not necessarily imply that the lower paid worker is disadvantaged; and analysis should focus on the overall subjective well-being or utility derived from a job, not on pay alone. [ABSTRACT FROM AUTHOR]

An academic learning network consists of multiple knowledge organizations and knowledge workers. The intellectual relationships can be derived from the interactions among them. In this paper, we propose a formal model to describe the interactions in an academic learning network and further provide an evaluation process to quantify intellectual relationships. Our approach is also integrated with a realistic social network platform SMNET. [ABSTRACT FROM AUTHOR]

The unprecedented scale of Information Technology (IT) service delivery requires careful analysis and optimization of service systems. The simulation is an efficient way to handle the complexity of modeling and optimization of real-world service delivery systems. However, typically developed custom simulation models lack standard architectures and limit the reuse of design and implementation artifacts across multiple models. In this work, following the design science research methodology, based on a formal model of service delivery systems and applying an adapted software product line (SPL) approach, we create a design artifact for building product lines of IT service delivery simulation models, which vastly simplify and reduce the cost of simulation model design and development. We evaluate the design artifact by constructing a product line of simulation models for a set of IBM’s IT service delivery systems. We validate the proposed approach by comparing the simulation results obtained using our models with the results from the corresponding custom simulation models. The case study demonstrates that the proposed approach leads to 5–8 times reductions in the time required to design and develop related simulation models. The potential implications of the application of the proposed approach within an organization are quicker responses to changes in the business environment, more information to assist in managerial decisions, and reduced workload on the process reengineering specialists. [ABSTRACT FROM AUTHOR]

Smart robots and smart services using robots are promising research fields in academia and industry. However, those smart services are based on basic motions of the robot, such as grabbing objects, and moving them to a designated place. In this paper, we propose a way to produce new motions without programming, from existing motions, through a motion composition method. Our motion composition method utilizes an Action Petri net, which is a variance of a Petri net, with both interpolation and composition operations on a transition. In the Action Petri net, a place is a posture or a moving action of a robot, and it is represented as a diagonal matrix with the robot's joint motor values. Robot motions can be generated from one posture to another posture, and from composing different postures and moving actions. All operations performed to generate new motions are carried out as matrix manipulation operations. Our approach provides a formal method to generate new motions from existing motions, and a practical method to create new motions in low level motion control, without programming. [ABSTRACT FROM AUTHOR]

Software Defined Networking (SDN) is an approach to building computer networks that separate and abstract data planes and control planes of these systems. In a SDN a centralized controller manages a distributed set of switches. A set of open commands for packet forwarding and flow table updating was defined in the form of a protocol known as OpenFlow. In this paper we describe an abstract formal model of SDN, introduce a tentative language for specification of SDN forwarding policies, and set up formally model-checking problems for SDNs. [ABSTRACT FROM AUTHOR]