4,796 research outputs found
Causal Consistency for Reversible Multiparty Protocols
In programming models with a reversible semantics, computational steps can be
undone. This paper addresses the integration of reversible semantics into
process languages for communication-centric systems equipped with behavioral
types. In prior work, we introduced a monitors-as-memories approach to
seamlessly integrate reversible semantics into a process model in which
concurrency is governed by session types (a class of behavioral types),
covering binary (two-party) protocols with synchronous communication. The
applicability and expressiveness of the binary setting, however, is limited.
Here we extend our approach, and use it to define reversible semantics for an
expressive process model that accounts for multiparty (n-party) protocols,
asynchronous communication, decoupled rollbacks, and abstraction passing. As
main result, we prove that our reversible semantics for multiparty protocols is
causally-consistent. A key technical ingredient in our developments is an
alternative reversible semantics with atomic rollbacks, which is conceptually
simple and is shown to characterize decoupled rollbacks.Comment: Extended, revised version of a PPDP'17 paper
(https://doi.org/10.1145/3131851.3131864
Session Types with Runtime Adaptation: Overview and Examples
In recent work, we have developed a session types discipline for a calculus
that features the usual constructs for session establishment and communication,
but also two novel constructs that enable communicating processes to be
stopped, duplicated, or discarded at runtime. The aim is to understand whether
known techniques for the static analysis of structured communications scale up
to the challenging context of context-aware, adaptable distributed systems, in
which disciplined interaction and runtime adaptation are intertwined concerns.
In this short note, we summarize the main features of our session-typed
framework with runtime adaptation, and recall its basic correctness properties.
We illustrate our framework by means of examples. In particular, we present a
session representation of supervision trees, a mechanism for enforcing
fault-tolerant applications in the Erlang language.Comment: In Proceedings PLACES 2013, arXiv:1312.221
Towards a Unified Framework for Declarative Structured Communications
We present a unified framework for the declarative analysis of structured
communications. By relying on a (timed) concurrent constraint programming
language, we show that in addition to the usual operational techniques from
process calculi, the analysis of structured communications can elegantly
exploit logic-based reasoning techniques. We introduce a declarative
interpretation of the language for structured communications proposed by Honda,
Vasconcelos, and Kubo. Distinguishing features of our approach are: the
possibility of including partial information (constraints) in the session
model; the use of explicit time for reasoning about session duration and
expiration; a tight correspondence with logic, which formally relates session
execution and linear-time temporal logic formulas
Self-Adaptation and Secure Information Flow in Multiparty Structured Communications: A Unified Perspective
We present initial results on a comprehensive model of structured
communications, in which self- adaptation and security concerns are jointly
addressed. More specifically, we propose a model of self-adaptive, multiparty
communications with secure information flow guarantees. In this model, security
violations occur when processes attempt to read or write messages of
inappropriate security levels within directed exchanges. Such violations
trigger adaptation mechanisms that prevent the violations to occur and/or to
propagate their effect in the choreography. Our model is equipped with local
and global mechanisms for reacting to security violations; type soundness
results ensure that global protocols are still correctly executed, while the
system adapts itself to preserve security.Comment: In Proceedings BEAT 2014, arXiv:1408.556
Cross-lingual Linking on the Multilingual Web of Data (position statement)
Recently, the Semantic Web has experienced signiïżœcant advancements in standards and techniques, as well as in the amount of semantic information available online. Even so, mechanisms are still needed to automatically reconcile semantic information when it is expressed in diïżœerent natural languages, so that access to Web information across language barriers can be improved. That requires developing techniques for discovering and representing cross-lingual links on the Web of Data. In this paper we explore the different dimensions of such a problem and reflect on possible avenues of research on that topic
Using Cross-Lingual Explicit Semantic Analysis for Improving Ontology Translation
Semantic Web aims to allow machines to make inferences using the explicit conceptualisations contained in ontologies. By pointing to ontologies, Semantic Web-based applications are able to inter-operate and share common information easily. Nevertheless, multilingual semantic applications are still rare, owing to the fact that most online ontologies are monolingual in English. In order to solve this issue, techniques for ontology localisation and translation are needed. However, traditional machine translation is difficult to apply to ontologies, owing to the fact that ontology labels tend to be quite short in length and linguistically different from the free text paradigm. In this paper, we propose an approach to enhance machine translation of ontologies based on exploiting the well-structured concept descriptions contained in the ontology. In particular, our approach leverages the semantics contained in the ontology by using Cross Lingual Explicit Semantic Analysis (CLESA) for context-based disambiguation in phrase-based Statistical Machine Translation (SMT). The presented work is novel in the sense that application of CLESA in SMT has not been performed earlier to the best of our knowledge
On the reduction of 4-oxo-4h-benzopyran-3-carbaldehydes : global and local electrophilicity patterns
The theoretical global and local electrophilicity patterns of substituted and chelated
4-oxo-4H-benzopyran-3-carbaldehydes (formylchromones) have been evaluated using the electrophilicity
index proposed by Parr et al [J. Am. Chem. Soc. 1999, 121, 1922]. The complexation of formylchromones
with aluminum predicts a strong electrophilic character of these compounds against nucleophiles.
Local response at the active sites may also be assessed in terms of a global contribution described by
the global electrophilicity, and a local contribution described by the variations in electrophilic
Fukui function at those sites. The highest local electrophilicity is found at the formyl group of
the chelated formylchromones, in spite of that, the highest positive charge is located on the pyrone
carbonyl group. This result is consistent with the experimental observed reactivity displayed by
4-oxo-4H-benzopyran-3-carbaldehydes in the presence of 2-propanol and alumina
A Typed Model for Dynamic Authorizations
Security requirements in distributed software systems are inherently dynamic.
In the case of authorization policies, resources are meant to be accessed only
by authorized parties, but the authorization to access a resource may be
dynamically granted/yielded. We describe ongoing work on a model for specifying
communication and dynamic authorization handling. We build upon the pi-calculus
so as to enrich communication-based systems with authorization specification
and delegation; here authorizations regard channel usage and delegation refers
to the act of yielding an authorization to another party. Our model includes:
(i) a novel scoping construct for authorization, which allows to specify
authorization boundaries, and (ii) communication primitives for authorizations,
which allow to pass around authorizations to act on a given channel. An
authorization error may consist in, e.g., performing an action along a name
which is not under an appropriate authorization scope. We introduce a typing
discipline that ensures that processes never reduce to authorization errors,
even when authorizations are dynamically delegated.Comment: In Proceedings PLACES 2015, arXiv:1602.0325
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