Showing papers by "Maciej Koutny published in 1995"

Semantics of inhibitor nets

Abstract: We discuss an abstract semantics of concurrent systems generalising causal partial orders. The new semantics employs relational structures-called stratified order structures-which comprise causal partial orders and weak causal partial orders. Stratified order structures can be represented by certain equivalence classes of step sequences-comtraces-directly generalising Mazurkiewicz traces. We use Elementary Net Systems with inhibitor arcs as a system model and show that stratified order structures can provide an abstract semantics which is consistent with their operational semantics expressed in terms of step sequences. Two different types of operational rules are considered. We also construct occurrence nets to enable the generation of stratified order structures for a given run of the net.

A Refined View of the Box Algebra

Abstract: This paper presents the operational semantics and the Petri net semantics of a fragment of the box algebra in tutorial style. For the operational semantics, inductive rules for marked expressions are given. For the net semantics, a general mechanism of refinement and relabelling is introduced, using which the connectives of the algebra are defined. A companion paper shows how this mechanism can be extended to handle recursion.

Solving Recursive Net Equations

Abstract: This paper describes a denotational approach to the Petri net semantics of recursive expressions. A domain of nets is identified such that the solution of a given recursive equation can be found by fixpoint approximation from some suitable starting point. In turn, a suitable starting point can be found by fixpoint approximation on a derived domain of sets of trees. The paper explains the theory on a series of examples and then summarises the most important results.

On compositionality and Petri nets in protocol engineering

Abstract: This paper addresses the problem of designing communication protocols within the Petri net approach Some recent results in combining Petri nets and compositionality are presented, and we argue that it should be possible to exploit these for protocol engineering We outline a systematic approach to the design of protocol systems At the top level, we use Petri net entities together with a set of operations The external behaviour of entities is characterised using the notion of a bisimulation equivalence At a lower level of design, we show how entities can be constructed from protocol procedures using suitable composition rules The relationship between syntactic and behavioural notions of compositionality is also discussed