41,069 research outputs found
Measurable Stochastics for Brane Calculus
We give a stochastic extension of the Brane Calculus, along the lines of
recent work by Cardelli and Mardare. In this presentation, the semantics of a
Brane process is a measure of the stochastic distribution of possible
derivations. To this end, we first introduce a labelled transition system for
Brane Calculus, proving its adequacy w.r.t. the usual reduction semantics.
Then, brane systems are presented as Markov processes over the measurable space
generated by terms up-to syntactic congruence, and where the measures are
indexed by the actions of this new LTS. Finally, we provide a SOS presentation
of this stochastic semantics, which is compositional and syntax-driven.Comment: In Proceedings MeCBIC 2010, arXiv:1011.005
An Operational Petri Net Semantics for the Join-Calculus
We present a concurrent operational Petri net semantics for the
join-calculus, a process calculus for specifying concurrent and distributed
systems. There often is a gap between system specifications and the actual
implementations caused by synchrony assumptions on the specification side and
asynchronously interacting components in implementations. The join-calculus is
promising to reduce this gap by providing an abstract specification language
which is asynchronously distributable. Classical process semantics establish an
implicit order of actually independent actions, by means of an interleaving. So
does the semantics of the join-calculus. To capture such independent actions,
step-based semantics, e.g., as defined on Petri nets, are employed. Our Petri
net semantics for the join-calculus induces step-behavior in a natural way. We
prove our semantics behaviorally equivalent to the original join-calculus
semantics by means of a bisimulation. We discuss how join specific assumptions
influence an existing notion of distributability based on Petri nets.Comment: In Proceedings EXPRESS/SOS 2012, arXiv:1208.244
Process Algebras
Process Algebras are mathematically rigorous languages with well defined semantics that permit describing and verifying properties of concurrent communicating systems.
They can be seen as models of processes, regarded as agents that act and interact continuously with other similar agents and with their common environment. The agents may be real-world objects (even people), or they may be artifacts, embodied perhaps in computer hardware or software systems.
Many different approaches (operational, denotational, algebraic) are taken for describing the meaning of processes. However, the operational approach is the reference one. By relying on the so called Structural Operational Semantics (SOS), labelled transition systems are built and composed by using the different operators of the many different process algebras. Behavioral equivalences are used to abstract from unwanted details and identify those systems that react similarly to external
experiments
Rewriting Logic Semantics of a Plan Execution Language
The Plan Execution Interchange Language (PLEXIL) is a synchronous language
developed by NASA to support autonomous spacecraft operations. In this paper,
we propose a rewriting logic semantics of PLEXIL in Maude, a high-performance
logical engine. The rewriting logic semantics is by itself a formal interpreter
of the language and can be used as a semantic benchmark for the implementation
of PLEXIL executives. The implementation in Maude has the additional benefit of
making available to PLEXIL designers and developers all the formal analysis and
verification tools provided by Maude. The formalization of the PLEXIL semantics
in rewriting logic poses an interesting challenge due to the synchronous nature
of the language and the prioritized rules defining its semantics. To overcome
this difficulty, we propose a general procedure for simulating synchronous set
relations in rewriting logic that is sound and, for deterministic relations,
complete. We also report on two issues at the design level of the original
PLEXIL semantics that were identified with the help of the executable
specification in Maude
Lean and Full Congruence Formats for Recursion
In this paper I distinguish two (pre)congruence requirements for semantic
equivalences and preorders on processes given as closed terms in a system
description language with a recursion construct. A lean congruence preserves
equivalence when replacing closed subexpressions of a process by equivalent
alternatives. A full congruence moreover allows replacement within a recursive
specification of subexpressions that may contain recursion variables bound
outside of these subexpressions.
I establish that bisimilarity is a lean (pre)congruence for recursion for all
languages with a structural operational semantics in the ntyft/ntyxt format.
Additionally, it is a full congruence for the tyft/tyxt format.Comment: To appear in: Proc. LICS'17, Reykjavik, Iceland, IEE
A Provenance Tracking Model for Data Updates
For data-centric systems, provenance tracking is particularly important when
the system is open and decentralised, such as the Web of Linked Data. In this
paper, a concise but expressive calculus which models data updates is
presented. The calculus is used to provide an operational semantics for a
system where data and updates interact concurrently. The operational semantics
of the calculus also tracks the provenance of data with respect to updates.
This provides a new formal semantics extending provenance diagrams which takes
into account the execution of processes in a concurrent setting. Moreover, a
sound and complete model for the calculus based on ideals of series-parallel
DAGs is provided. The notion of provenance introduced can be used as a
subjective indicator of the quality of data in concurrent interacting systems.Comment: In Proceedings FOCLASA 2012, arXiv:1208.432
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