Hans Van Der Schoot

Dataflow oriented test selection for LOTOS

Abstract A data flow oriented test selection method for selectively generating abstract tests from a lotos specification is presented. This method is based on static data flow analysis to identify maximal io -df-chains, which exhibit the associations between each specification output and those specification inputs that influence the output through definitions and uses of variables. The maximal io -df-chains are then used to guide the derivation of test sequences. A new set of inference rules is introduced for this purpose. As an illustration, the test selection method is applied to the alternating bit protocol.

An improvement of partial‐order verification

Partial‐order reduction methods form a collection of state exploration techniques set to relieve the state‐explosion problem in concurrent program verification. Their use often reduces significantly the memory needed for verifying local and termination properties of concurrent programs and, moreover, for verifying that concurrent programs satisfy their linear‐time temporal logic specifications (i.e. for LTL model‐checking). One particular such method is implemented in the verification system SPIN, which is considered to be one of the most efficient and most widely used LTL model‐checkers. This paper builds on SPINs partial‐order reduction method to yield an approach that enables further space reductions for verifying concurrent programs.

Data Flow Analysis of System Specifications in Lotos

In LOTOS, a system is specified as a behaviour expression describing the externally observable behaviour of the system in terms of possible sequences of interactions between the system and its environment. The desired control flow and data flow that must be established by a possible implementation of the system are specified in the behaviour expression as implicit enumerations of allowed sequences of interaction identifiers and relationships among interaction parameters, respectively. A model exposing the desired flow of data within the allowed control flow expressed in a system specification in LOTOS is presented. Based on the explicit information provided by the model, data flow anomaly detection and data flow oriented test selection are facilitated. A comprehensive example, i.e. an alternating bit protocol specification, is used to illustrate both these validation activities. An error in this specification is revealed by the analysis of a data flow anomaly detected within the specification. A set of test paths is derived from the specification by the application of an existing data flow oriented test selection criterion, called all-uses criterion.

On generalizing fair reachability analysis to protocols with arbitrary topology

Fair rwchability analysis is generalized to multi-cyclic protocols defined in the CFSM model as networks of n >2 processes with a multiple unidirectional ring topology and with arbitrary process structures. As a restdt, the deadlock detection problem is shown to be decidable for multi-cyclic protocols whose fair reachable global state space kfinite. A suficient conditwn for this>niteness is also given. Finally, it is argued that the technkp of fm”r reachability anakis cannot be extended beyond multi-cvclic protocols.