. We outline a methodology for the modular specification of telephone services within first-order linear-time temporal logic. Typically, the services offered by a telephone system consist of a basic service and several optional additional services, such as automatic callback, redirection, etc. We argue informally that temporal logic provides a flexible formalism for the specification of individual services, and for the composition of different services. We present a style of specification, in which the expected behavior of each additional service can be specified independently of other services. In this style, it is straight-forward to compose noninteracting services. We outline, by means of examples, how certain interactions between services that prescribe conflicting behavior can manifest themselves as inconsistencies when the services are composed. We then outline how the resolution of such interactions can be described in the formalism. 1 Introduction The difficulty of designing ...

. A simple and elegant formulation of compositional proof systems for concurrent programs results from a refinement of temporal logic semantics. The refined temporal language we propose is closed under w- stuttering and, thus, provides a fully abstract semantics with respect to some chosen observation level w. This avoids incorporating irrelevant detail in the temporal semantics of parallel programs. Besides compositional verification, concurrent program design and implementation of a coarser-grained program by a finer-grained one, turn out to be easily practicable in the setting of the new temporal logic. 1 Introduction The regular temporal logic [14, 16] provides a powerful tool for global specification and non-compositional verification of existing concurrent programs. However, this logic offers a very poor support for modular specification and verification and, consequently, systematic design of concurrent programs is hard (if not impossible) to do in such a setting. The lack of ...

. A simple and elegant formulation of compositional proof systems for concurrent programs results from a refinement of temporal logic semantics. The refined temporal language we propose is closed under w-stuttering and, thus, provides a fully abstract semantics with respect to some chosen observation level w. This avoids incorporating irrelevant detail in the temporal semantics of parallel programs. Besides compositional verification, concurrent program design and implementation of a coarser-grained program by a finer-grained one, are easily practicable in the setting of the new temporal logic. 1 Introduction A well-known problem for the verification and the construction of concurrent programs is that specifications that would be satisfied by a given process viewed in isolation, might be invalidated by actions performed by other processes executing in parallel. Composition principles provide a way to overcome this problem [2, 3, 28]. In compositional verification, properties of...

Feature interaction problems are currently a major roadblock to extending and changing telephone switching systems, which have to follow market needs quickly. Such problems appear already in the requirements specifications. We avoid certain kinds of feature interactions by employing a more modular specification structure. First, we show how the details of the users' interface, like buttons and ring tones, can be encapsulated and separated from the system's functionality. Such an architecture could be realized even within the structure of the current standard for the Intelligent Network (IN). Second, we argue that the requirements for the Plain Old Telephone Service (POTS) comprehend several different concerns, and that separate requirement concerns should be separated in the specification. We employ the Functional Documentation approach [PaMa95, vSPM93, vS92a] and investigate how it can be extended to group requirement concerns, and to cover not only one but a sequence of development contracts. Our approach is related to the standard refinement approach for software development. But when we refine a specification to introduce new services, we order the refinement steps (i.e., the new required properties) by the likeliness by which they must be taken back, and we document the dependences between these steps explicitly. In the appendix, we provide a case study that applies our ideas.

Linear time temporal logic (LTL) has received a lot of attention as a language for program specification and verification. Unfortunately, not all properties expressed in LTL are closed under stuttering, a property important from both the practical and philosophical perspectives. In this thesis we develop a formal theory of closure under stuttering within the larger framework of Unified Algebra, give theorems that enable syntactic reasoning about closure under stuttering, introduce the notion of edges in LTL formulas, and present several real-world applications of the theory developed thus far.

Introduction The use of temporal logic has been widely explored both on the fields of specification and certification of properties of reactive systems (Pnueli, 1977), (Sernadas, 1980), (Fiadeiro and Maibaum, 1992), (Clarke, Grumberg and Kurshan, 1992), (Manna and Pnueli, 1992), (Manna and Pnueli, 1993), (Sernadas, Sernadas and Costa, 1995), (Sernadas, Sernadas and Ramos, 1996) and in monitoring (Hulsmann and Saake, 1991), (Kung, 1984), (Lipeck and Saake, 1987), (Schwiderski, Hartmann and Saake, 1994). The advantages are known to lie on the clear declarative formalization of the system at hand and on the use of temporal verification techniques to prove properties of the specified systems. Temporal logic specification has also given an important contribution towards the establishment of suitable compositional specification frameworks (Barringer, Kuiper and Pnueli, 1984). -- This work was partly supported by CEC under ESPRIT-III BRA WG 6071 IS-CORE (Information S

. A formal framework for specifying and verifying real-time systems with a continuous environment is presented. Metric Temporal Logic (MTL) is extended with a duration concept similar to the one in the Duration Calculus (DC). The resulting logic, called MTL- R , is compared with DC and is shown to be more expressive. Axioms for MTL- R and a sound rule to prove that a timed transition system satisfies a limitedduration property are given. 1 Introduction Hybrid systems are reactive systems involving components with continuous changes. Computer controlled manufacturing and transport systems are typical hybrid systems with discrete components, as the control program, that act in a continuous environment. Hybrid systems are by far the most complex and critical reactive systems; therefore, formal methods for their analysis, synthesis, and verification are needed. Although many systems can be analyzed in a model where continuous changes are represented by discrete events, this may lead i...

mandatory calls specified by model programs

Abstract. Nowadays the software systems, including web portals, are developed from a priori assumptions about how the system will be used. However, frequently these assumptions hold only partly and are defined also partially. Therefore one must be capable to compare the a priori assumptions with the actual user behavior in order to decide how the system could be improved. To tackle this problem, we consider a promising approach to employ the same formalism to express the intended usage, the web portal model and the frequent real usage patterns, extracted from the experimental data by data mining algorithms. This allows to automate the verification whether the frequent real usage patterns satisfy the intended usage in the web portal model. We propose to use temporal logic and Kripke structure as such a common formalism.