An event structure model for dataflow computing

The intention of the paper is to provide "true" concurrency semantics to dynamic dataflow computing. To this end, we study the behaviour of coloured dataflow networks comparatively, incorporating such concepts as firing sequences,  data dependence graphs, partial orders and event structures. The coincidence of the above semantic notions up to an isomorphism  is established.  In particular, the classes of well-formed coloured dataflow networks and prime event structures are examined

On Varieties of Density and Crossing Properties for Event Structures

We study prime event structures as models for nondeterministic processes and some of their properties known as discreteness, density and crossing. These properties allow inconsistency to be avoided between syntactic and semantic representations of processes. A number close relationships between different density and crossing concepts is established. It has turned out that in an M-dense event structure all of the executions are completely  "successful" (i.e. at least one successor (if it exists) for any event occurring in the execution must also occur)

History-dependent stochastic Petri nets

Stochastic Petri Nets are a useful and well-known tool for performance analysis. However, an implicit assumption in the different types of Stochastic Petri Nets is the Markov property. It is assumed that a choice in the Petri net only depends on the current state and not on earlier choices. For many real-life processes, choices made in the past can influence choices made later in the process. For example, taking one more iteration in a loop might increase the probability to leave the loop, etc. In this paper, we introduce a novel framework where probability distributions depend not only on the marking of the net, but also on the history of the net. We also describe a number of typical abstraction functions for capturing relevant aspects of the net’s history and show how we can discover the probabilistic mechanism from event logs, i.e. real-life observations are used to learn relevant correlations. Finally, we present how our nets can be modelled and simulated using CPN Tools and discuss the results of some simulation experiments

TTCN-3 for distributed testing embedded systems

Abstract. TTCN-3 is a standardized language for specifying and executing test suites that is particularly popular for testing embedded systems. Prior to testing embedded software in a target environment, the software is usually tested in the host environment. Executing in the host environment often affects the real-time behavior of the software and, consequently, the results of real-time testing. Here we provide a semantics for host-based testing with simulated time and a a simulated-time solution for distributed testing with TTCN-3

Comparing logical and behavioural equivalences for event structures

The intention of the paper is to establish a match between the equivalence induced by the partial order logic L_1 [7] and behavioural equivalences defined directly over prime event structures. Unlike other logical formalisms, the language L_1 has modalities expressing concurrency and conflict, in addition to usual past and future modalities. A relating the logical equivalence to behavioural ones provides between understanding the essentiality of the logic L_1 and its place among the classical temporal languages (e.g., CTL, LTL, POL, etc.). For this purpose a number of new bisimulations which respect causality, concurrency and conflict relations between occurrences of events in the structures are proposed. Building the lattice of equivalences we show that there are the close relationships between the introduced and existing bisimulation notions. The question of preservation of the considered equivalences under action refinement is also treated. (orig.)Available from TIB Hannover: RO 8347(1996,22)+a / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman