249 research outputs found
Disjunctive Probabilistic Modal Logic is Enough for Bisimilarity on Reactive Probabilistic Systems
Larsen and Skou characterized probabilistic bisimilarity over reactive
probabilistic systems with a logic including true, negation, conjunction, and a
diamond modality decorated with a probabilistic lower bound. Later on,
Desharnais, Edalat, and Panangaden showed that negation is not necessary to
characterize the same equivalence. In this paper, we prove that the logical
characterization holds also when conjunction is replaced by disjunction, with
negation still being not necessary. To this end, we introduce reactive
probabilistic trees, a fully abstract model for reactive probabilistic systems
that allows us to demonstrate expressiveness of the disjunctive probabilistic
modal logic, as well as of the previously mentioned logics, by means of a
compactness argument.Comment: Aligned content with version accepted at ICTCS 2016: fixed minor
typos, added reference, improved definitions in Section 3. Still 10 pages in
sigplanconf forma
GSOS for non-deterministic processes with quantitative aspects
Recently, some general frameworks have been proposed as unifying theories for
processes combining non-determinism with quantitative aspects (such as
probabilistic or stochastically timed executions), aiming to provide general
results and tools. This paper provides two contributions in this respect.
First, we present a general GSOS specification format (and a corresponding
notion of bisimulation) for non-deterministic processes with quantitative
aspects. These specifications define labelled transition systems according to
the ULTraS model, an extension of the usual LTSs where the transition relation
associates any source state and transition label with state reachability weight
functions (like, e.g., probability distributions). This format, hence called
Weight Function SOS (WFSOS), covers many known systems and their bisimulations
(e.g. PEPA, TIPP, PCSP) and GSOS formats (e.g. GSOS, Weighted GSOS,
Segala-GSOS, among others).
The second contribution is a characterization of these systems as coalgebras
of a class of functors, parametric on the weight structure. This result allows
us to prove soundness of the WFSOS specification format, and that
bisimilarities induced by these specifications are always congruences.Comment: In Proceedings QAPL 2014, arXiv:1406.156
Distributed execution of bigraphical reactive systems
The bigraph embedding problem is crucial for many results and tools about
bigraphs and bigraphical reactive systems (BRS). Current algorithms for
computing bigraphical embeddings are centralized, i.e. designed to run locally
with a complete view of the guest and host bigraphs. In order to deal with
large bigraphs, and to parallelize reactions, we present a decentralized
algorithm, which distributes both state and computation over several concurrent
processes. This allows for distributed, parallel simulations where
non-interfering reactions can be carried out concurrently; nevertheless, even
in the worst case the complexity of this distributed algorithm is no worse than
that of a centralized algorithm
Representing Isabelle in LF
LF has been designed and successfully used as a meta-logical framework to
represent and reason about object logics. Here we design a representation of
the Isabelle logical framework in LF using the recently introduced module
system for LF. The major novelty of our approach is that we can naturally
represent the advanced Isabelle features of type classes and locales.
Our representation of type classes relies on a feature so far lacking in the
LF module system: morphism variables and abstraction over them. While
conservative over the present system in terms of expressivity, this feature is
needed for a representation of type classes that preserves the modular
structure. Therefore, we also design the necessary extension of the LF module
system.Comment: In Proceedings LFMTP 2010, arXiv:1009.218
Bigraphical models for protein and membrane interactions
We present a bigraphical framework suited for modeling biological systems
both at protein level and at membrane level. We characterize formally bigraphs
corresponding to biologically meaningful systems, and bigraphic rewriting rules
representing biologically admissible interactions. At the protein level, these
bigraphic reactive systems correspond exactly to systems of kappa-calculus.
Membrane-level interactions are represented by just two general rules, whose
application can be triggered by protein-level interactions in a well-de\"ined
and precise way. This framework can be used to compare and merge models at
different abstraction levels; in particular, higher-level (e.g. mobility)
activities can be given a formal biological justification in terms of low-level
(i.e., protein) interactions. As examples, we formalize in our framework the
vesiculation and the phagocytosis processes
Formalizing a lazy substitution proof system for \u3bc-calculus in the Calculus of Inductive Constructions
We present a Natural Deduction proof system for the pro- positional modal \u3bc-calculus, and its formalization in the Calculus of In- ductive Constructions. We address several problematic issues, such as the use of higher-order abstract syntax in inductive sets in presence of recursive constructors, the encoding of modal (sequent-style) rules and of context sensitive grammars. The formalization can be used in the sy- stem Coq, providing an experimental computer-aided proof environment for the interactive development of error-free proofs in the \u3bc-calculus. The techniques we adopt can be readily ported to other languages and proof systems featuring similar problematic issues. \ua9 Springer-Verlag Berlin Heidelberg 1999
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