69 research outputs found
Event Structure Semantics for CCS and Related Languages
We give denotational semantics to a wide range of parallel programming languages based on the ideas of Milner's CCS, that processes communicate by events of mutual synchronisation.Processes are denoted by labelled event structures. Event structures represent concurrency rather directly as in net theory.The semantics does not simulate concurrency by non-deterministic interleaving
On the Semantics of Petri Nets
Petri Place/Transition (PT) nets are one of the most widely used models of concurrency. However, they still lack, in our view, a satisfactory semantics: on the one hand the "token game"' is too intensional, even in its more abstract interpretations in term of nonsequential processes and monoidal categories; on the other hand, Winskel's basic unfolding construction, which provides a coreflection between nets and finitary prime algebraic domains, works only for safe nets. In this paper we extend Winskel's result to PT nets. We start with a rather general category {PTNets} of PT nets, we introduce a category {DecOcc} of decorated (nondeterministic) occurrence nets and we define adjunctions between {PTNets} and {DecOcc} and between {DecOcc} and {Occ}, the category of occurrence nets. The role of {DecOcc} is to provide natural unfoldings for PT nets, i.e. acyclic safe nets where a notion of family is used for relating multiple instances of the same place. The unfolding functor from {PTNets} to {Occ} reduces to Winskel's when restricted to safe nets, while the standard coreflection between {Occ} and {Dom}, the category of finitary prime algebraic domains, when composed with the unfolding functor above, determines a chain of adjunctions between {PTNets} and {Dom}
A Nice Labelling for Tree-Like Event Structures of Degree 3
We address the problem of finding nice labellings for event structures
of degree 3. We develop a minimum theory by which we prove that the labelling
number of an event structure of degree 3 is bounded by a linear function of the
height. The main theorem we present in this paper states that event structures
of degree 3 whose causality order is a tree have a nice labelling with 3
colors. Finally, we exemplify how to use this theorem to construct upper bounds
for the labelling number of other event structures of degree 3
The consistency of a noninterleaving and an interleaving model for full TCSP
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Reversible Barbed Congruence on Configuration Structures
A standard contextual equivalence for process algebras is strong barbed
congruence. Configuration structures are a denotational semantics for processes
in which one can define equivalences that are more discriminating, i.e. that
distinguish the denotation of terms equated by barbed congruence. Hereditary
history preserving bisimulation (HHPB) is such a relation. We define a strong
back and forth barbed congruence using a reversible process algebra and show
that the relation induced by the back and forth congruence is equivalent to
HHPB, providing a contextual characterization of HHPB.Comment: In Proceedings ICE 2015, arXiv:1508.0459
A Nice Labelling for Tree-Like Event Structures of Degree 3 (Extended Version)
We address the problem of finding nice labellings for event structures of
degree 3. We develop a minimum theory by which we prove that the labelling
number of an event structure of degree 3 is bounded by a linear function of the
height. The main theorem we present in this paper states that event structures
of degree 3 whose causality order is a tree have a nice labelling with 3
colors. Finally, we exemplify how to use this theorem to construct upper bounds
for the labelling number of other event structures of degree 3
Quantitative testing semantics for non-interleaving
This paper presents a non-interleaving denotational semantics for the
?-calculus. The basic idea is to define a notion of test where the outcome is
not only whether a given process passes a given test, but also in how many
different ways it can pass it. More abstractly, the set of possible outcomes
for tests forms a semiring, and the set of process interpretations appears as a
module over this semiring, in which basic syntactic constructs are affine
operators. This notion of test leads to a trace semantics in which traces are
partial orders, in the style of Mazurkiewicz traces, extended with readiness
information. Our construction has standard may- and must-testing as special
cases
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