Generalization Strategies for the Verification of Infinite State Systems

We present a method for the automated verification of temporal properties of infinite state systems. Our verification method is based on the specialization of constraint logic programs (CLP) and works in two phases: (1) in the first phase, a CLP specification of an infinite state system is specialized with respect to the initial state of the system and the temporal property to be verified, and (2) in the second phase, the specialized program is evaluated by using a bottom-up strategy. The effectiveness of the method strongly depends on the generalization strategy which is applied during the program specialization phase. We consider several generalization strategies obtained by combining techniques already known in the field of program analysis and program transformation, and we also introduce some new strategies. Then, through many verification experiments, we evaluate the effectiveness of the generalization strategies we have considered. Finally, we compare the implementation of our specialization-based verification method to other constraint-based model checking tools. The experimental results show that our method is competitive with the methods used by those other tools. To appear in Theory and Practice of Logic Programming (TPLP).Comment: 24 pages, 2 figures, 5 table

Simulation and formal verification of industrial systems controllers

Actually, the safety control is one of the most important aspects studied by the international researchers, in the field of design and development of automated production systems due to social (avoid work accidents, ...), economics (machine stop time reduction, increase of productivity,...) and technological aspects (less risks of damage of the components,...). Some researchers of the Engineering School of University of Minho are also studying these aspects of safety control, using simulation and modelchecking techniques in the development of Programmable Logic Controllers (PLC) programs. The techniques currently used for the guarantee of automated production systems control safety are the Simulation and the Formal Verification. If the Simulation is faster to execute, has the limitation of considering only some system behavior evolution scenarios. Using Formal Verification it exists the advantage of testing all the possible system behavior evolution scenarios but, sometimes, it exists the limitation of the time necessary for the attainment of formal verification results. In this paper it is shown, as it is possible, and desirable, to conciliate these two techniques in the analysis of PLC programs. With the simultaneous use of these two techniques, the developed PLC programs are more robust and not subject to errors. It is desirable the use of simulation before using formal verification in the analysis of a system control program because with the simulation of some possible system behaviors it is possible to eliminate a set of program errors in reduced intervals of time and that would not happen if these errors were detected only through the use of formal verification techniques. Conciliating these two techniques it can be substantially reduced the time necessary for the attainment of results through the use of the formal verification technique. For the analysis of a system control program for simulation and formal verification it is used the Dymola for the Simulation (through the creation of system models with Modelica language) and UPPAAL (through the creation of system models with timed automata)

Spacecraft Requirements Development and Tailoring

Spacecraft design is managed through the use of design requirements. Requirements are flowed from the highest level, the overall spacecraft, to systems, subsystems and ultimately individual components. Through the use of requirements, each part of the spacecraft will perform the functions that are required of it and will interface to the rest of the spacecraft. Functional requirements are used to make sure every component performs as expected and interface requirements ensure that each component works within the larger design environment where it operates. Writing good requirements is difficult and the verification of requirements can be expensive and time consuming. Because of this difficulty and expense, it is important that each requirement truly be required and critical to the overall performance of the vehicle. It is also important that requirements can be changed or eliminated as the system matures to minimize verification cost and schedule. The Capsule Parachute Assembly System (CPAS) Project is developing the parachute system for the NASA Multi-Purpose Crew Vehicle (MPCV) Orion Spacecraft. Throughout the development and qualification cycle for CPAS, requirements have been evaluated, added, eliminated, or more generically, tailored, to ensure that the system performs as required while minimizing the verification cost to the Program. One facet of this tailoring has been to delete requirements that do not add value to the overall spacecraft or are not needed. A second approach to minimize the cost of requirement verification has been to evaluate requirements based on the actual design as it has matured. As the design of the parachute system has become better understood, requirements that are not applicable have been eliminated. This paper will outline the evolution of CPAS requirements over time and will show how careful and considered changes to requirements can benefit the technical solution for the overall system design while allowing a Project to control costs

The Designated Suppliers Program (Revised Sept \u2706)

The Designated Suppliers Program is a system for protecting the rights of the workers who sew university logo apparel. Under the Designated Suppliers Program, university licensees are required to source most university logo apparel from supplier factories that have been determined by universities, through independent verification, to be in compliance with their obligation to respect the rights of their employees – including the right to organize and bargain collectively and the right to be paid a living wage. Licensees may bring any factory they choose into the program, provided the factory can demonstrate compliance with the program’s labor standards. The program is phased in over a three year period

Integrated testing and verification system for research flight software design document

The NASA Langley Research Center is developing the MUST (Multipurpose User-oriented Software Technology) program to cut the cost of producing research flight software through a system of software support tools. The HAL/S language is the primary subject of the design. Boeing Computer Services Company (BCS) has designed an integrated verification and testing capability as part of MUST. Documentation, verification and test options are provided with special attention on real time, multiprocessing issues. The needs of the entire software production cycle have been considered, with effective management and reduced lifecycle costs as foremost goals. Capabilities have been included in the design for static detection of data flow anomalies involving communicating concurrent processes. Some types of ill formed process synchronization and deadlock also are detected statically

Convex Programs for Temporal Verification of Nonlinear Dynamical Systems

A methodology for safety verification of continuous and hybrid systems using barrier certificates has been proposed recently. Conditions that must be satisfied by a barrier certificate can be formulated as a convex program, and the feasibility of the program implies system safety in the sense that there is no trajectory starting from a given set of initial states that reaches a given unsafe region. The dual of this problem, i.e., the reachability problem, concerns proving the existence of a trajectory starting from the initial set that reaches another given set. Using insights from the linear programming duality appearing in the discrete shortest path problem, we show in this paper that reachability of continuous systems can also be verified through convex programming. Several convex programs for verifying safety and reachability, as well as other temporal properties such as eventuality, avoidance, and their combinations, are formulated. Some examples are provided to illustrate the application of the proposed methods. Finally, we exploit the convexity of our methods to derive a converse theorem for safety verification using barrier certificates