Bounded Reachability for Temporal Logic over Constraint Systems

We present CLTLB(D), an extension of PLTLB (PLTL with both past and future operators) augmented with atomic formulae built over a constraint system D. Even for decidable constraint systems, satisfiability and Model Checking problem of such logic can be undecidable. We introduce suitable restrictions and assumptions that are shown to make the satisfiability problem for the extended logic decidable. Moreover for a large class of constraint systems we propose an encoding that realize an effective decision procedure for the Bounded Reachability problem

Non-null Infinitesimal Micro-steps: a Metric Temporal Logic Approach

Many systems include components interacting with each other that evolve with possibly very different speeds. To deal with this situation many formal models adopt the abstraction of "zero-time transitions", which do not consume time. These however have several drawbacks in terms of naturalness and logic consistency, as a system is modeled to be in different states at the same time. We propose a novel approach that exploits concepts from non-standard analysis to introduce a notion of micro- and macro-steps in an extension of the TRIO metric temporal logic, called X-TRIO. We use X-TRIO to provide a formal semantics and an automated verification technique to Stateflow-like notations used in the design of flexible manufacturing systems.Comment: 20 pages, 2 figures, submitted to the conference "FORMATS: Formal Modelling and Analysis of Timed Systems" 201

A Metric Encoding for Bounded Model Checking (extended version)

In Bounded Model Checking both the system model and the checked property are translated into a Boolean formula to be analyzed by a SAT-solver. We introduce a new encoding technique which is particularly optimized for managing quantitative future and past metric temporal operators, typically found in properties of hard real time systems. The encoding is simple and intuitive in principle, but it is made more complex by the presence, typical of the Bounded Model Checking technique, of backward and forward loops used to represent an ultimately periodic infinite domain by a finite structure. We report and comment on the new encoding technique and on an extensive set of experiments carried out to assess its feasibility and effectiveness

Advantages of Model-Based Development in terms of Business Benefits

Today’s industries require quick reactions and high-quality solutions. Businesses want to keep costs and resource misuse to a minimum for greater benefits. Automated processes can suit the efficiency needed in businesses. In the software field, this means quick development time and maintainability. Different methods have advantages towards these goals. One of these methods is model-based development. This thesis analyses model-based development as the method emphasises automation effi-ciency and high quality. Model-based development is based on capturing required elements in-to a model. The model is processed with appropriate tools to form a wanted outcome. The tools tend to be highly automatic. The approach is applied in different development fields, more with practical simpler systems than complex software. The simpler ones usually have functional behaviour that can be modelled easier. This thesis includes multiple advantages of a model-based approach that can answer the needs and requirements of industries, even overcome them. Advantages like reduced development time with high quality and model reusability can result in business-level benefits. To exploit the benefits in today’s state requires costs and effort as they are many times needed to be performed in a specific environment and with specific tools. The environment sets the need for specific knowledge of practises and effort in understanding the method to succeed. The challenges are needed to be overcome by more generally applicable solutions. The analysing of the advantages in this thesis shows that there is no significant benefit that can be achieved through model-based development. The benefits are due to the overall advantageous nature of the approach. While the commercial usage of the model-based development is still narrow, there is a future for the methodology. Research regarding model-based development is refining the used concepts and providing new ways to exploit the advantages

Refining Real-Time System Specifications through Bounded Model- and Satisfiability-Checking

In Bounded Model Checking (BMC) a system is modeled with a finite automaton and various desired properties with temporal logic formulae. Property verification is achieved by translation into boolean logic and the application of SAT- solvers. Bounded Satisfiability Checking (BSC) adopts a similar approach, but both the system and the properties are modeled with temporal logic formulae, without an underlying operational model. Hence, BSC supports a higher-level, descriptive approach to system specification and analysis. We compare the performance of BMC and BSC over a set of case studies, using the Zot tool to translate automata and temporal logic formulae into boolean logic. We also propose a method to check whether an operational model is a correct implementation (refinement) of a temporal logic model, and assess its effectiveness on the same set of case studies. Our experimental results show the feasibility of BSC and refinement checking, with modest performance loss w.r.t. BMC