8 research outputs found
Higher-Dimensional Timed Automata
We introduce a new formalism of higher-dimensional timed automata, based on
van Glabbeek's higher-dimensional automata and Alur's timed automata. We prove
that their reachability is PSPACE-complete and can be decided using zone-based
algorithms. We also show how to use tensor products to combat state-space
explosion and how to extend the setting to higher-dimensional hybrid automata
Sculptures in Concurrency
We give a formalization of Pratt's intuitive sculpting process for
higher-dimensional automata (HDA). Based on this, we show that sculptures,
Pratt's Chu spaces, and Johansen's ST-structures are in close correspondence.
We also develop an algorithm to decide whether a HDA can be sculpted and use
this to show that some natural acyclic HDA are not sculptures. We believe that
our result shed new light on the intuitions behind sculpting as a method of
modeling concurrent behavior, showing the precise reaches of its
expressiveness. We also show that there are sculptures whose unfoldings cannot
besculpted, and that sculptures are the same as Euclidean cubical complexes.
This exposes a close connection between geometric and combinatorial models for
concurrency which may be of use for both areas
A new operational representation of dependencies in Event Structures
The execution of an event in a complex and distributed system where the
dependencies vary during the evolution of the system can be represented in many
ways, and one of them is to use Context-Dependent Event structures. Event
structures are related to Petri nets. The aim of this paper is to propose what
can be the appropriate kind of Petri net corresponding to Context-Dependent
Event structures, giving an operational flavour to the dependencies represented
in a Context/Dependent Event structure. Dependencies are often operationally
represented, in Petri nets, by tokens produced by activities and consumed by
others. Here we shift the perspective using contextual arcs to characterize
what has happened so far and in this way to describe the dependencies among the
various activities
A Petri net view of covalent bonds
In nature and chemistry the interactions among elements often form bonds and among them covalent bonds are relevant, involving the sharing of electrons. Another relevant and compelling facet of calculi modelling covalent bonds is that certain steps in reactions are the result of concerting different activities, possibly reversing some of them. Starting from a calculus for covalent bonds, we investigate on how it can be done in a compositional fashion and how it can be encoded in suitable Petri nets. The outcome gives us a compositional covalent bond calculus and a truly distributed implementation. On these results it is possible to build a behavioural equivalence among terms.Fil: Melgratti, Hernan Claudio. Consejo Nacional de Investigaciones CientÃficas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Investigación en Ciencias de la Computación. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Investigación en Ciencias de la Computación; ArgentinaFil: Mezzina, Claudio Antares. Università Degli Studi Di Urbino Carlo Bo; ItaliaFil: Pinna, G. Michele. Università degli Studi di Cagliari; Itali
Petri nets and dynamic causality for service-oriented computations
When dealing with service oriented computations the dependencies among the various distributed activities may be complex and difficult to represent statically. Recently Event Structures where the causality may change dynamically have been introduced and have been related with many other kind of Event Structures (with a particular focus on expressivity). In this paper we relate them to a kind of (labeled) Petri net which turns out to cover these new Event Structures. This relationship empowers the usage of all the available verification tools based on Petri nets, giving practical and usable means for the verification of the complex and distributed system whose behavior is modeled by this kind of event structures