383 research outputs found
Reversible Multiparty Sessions with Checkpoints
Reversible interactions model different scenarios, like biochemical systems
and human as well as automatic negotiations. We abstract interactions via
multiparty sessions enriched with named checkpoints. Computations can either go
forward or roll back to some checkpoints, where possibly different choices may
be taken. In this way communications can be undone and different conversations
may be tried. Interactions are typed with global types, which control also
rollbacks. Typeability of session participants in agreement with global types
ensures session fidelity and progress of reversible communications.Comment: In Proceedings EXPRESS/SOS 2016, arXiv:1608.0269
Parallel Monitors for Self-adaptive Sessions
The paper presents a data-driven model of self-adaptivity for multiparty
sessions. System choreography is prescribed by a global type. Participants are
incarnated by processes associated with monitors, which control their
behaviour. Each participant can access and modify a set of global data, which
are able to trigger adaptations in the presence of critical changes of values.
The use of the parallel composition for building global types, monitors and
processes enables a significant degree of flexibility: an adaptation step can
dynamically reconfigure a set of participants only, without altering the
remaining participants, even if the two groups communicate.Comment: In Proceedings PLACES 2016, arXiv:1606.0540
Session Type Isomorphisms
There has been a considerable amount of work on retrieving functions in
function libraries using their type as search key. The availability of rich
component specifications, in the form of behavioral types, enables similar
queries where one can search a component library using the behavioral type of a
component as the search key. Just like for function libraries, however,
component libraries will contain components whose type differs from the
searched one in the order of messages or in the position of the branching
points. Thus, it makes sense to also look for those components whose type is
different from, but isomorphic to, the searched one.
In this article we give semantic and axiomatic characterizations of
isomorphic session types. The theory of session type isomorphisms turns out to
be subtle. In part this is due to the fact that it relies on a non-standard
notion of equivalence between processes. In addition, we do not know whether
the axiomatization is complete. It is known that the isomorphisms for arrow,
product and sum types are not finitely axiomatisable, but it is not clear yet
whether this negative results holds also for the family of types we consider in
this work.Comment: In Proceedings PLACES 2014, arXiv:1406.331
Secure Multiparty Sessions with Topics
Multiparty session calculi have been recently equipped with security
requirements, in order to guarantee properties such as access control and leak
freedom. However, the proposed security requirements seem to be overly
restrictive in some cases. In particular, a party is not allowed to communicate
any kind of public information after receiving a secret information. This does
not seem justified in case the two pieces of information are totally unrelated.
The aim of the present paper is to overcome this restriction, by designing a
type discipline for a simple multiparty session calculus, which classifies
messages according to their topics and allows unrestricted sequencing of
messages on independent topics.Comment: In Proceedings PLACES 2016, arXiv:1606.0540
From Böhm's Theorem to Observational Equivalences an Informal Account1 1Partially supported by MURST Cofin '00 AITCFA and MCTAAP II Projects.
AbstractThere are essentially two ways of looking at the computational behaviours of λ-terms. One consists in putting the term within a context (possibly of λ-calculus extensions) and observing some properties (typically termination). The other consists in reducing the term until some meaningful information is obtained: this naturally leads to a tree representation of the information implicitly contained in the original term. The paper is an informal overview of the role played by Böhm's Theorem in these observations of terms
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
A characterization of F-complete type assignments
AbstractThe aim of this paper is to investigate the soundness and completeness of the intersection type discipline (for terms of the (untyped λ-calculus) with respect to the F-semantics (F-soundness and F-completeness).As pointed out by Scott, if D is the domain of a Îł-model, there is a subset F of D whose elements are the âcanonicalâ representatives of functions. The F-semantics of types takes into account that theintuitive meaning of âÏâÏâ is âthe type of functions with domain Ï and range Ïâ and interprets ÏâÏ as a subset of F.The type theories which induce F-complete type assignments are characterized. It follows that a type assignment is F-complete iff equal terms get equal types and, whenever M has a type Ïâ§Ïn, where Ï is a type variable and Ï is the âuniversalâ type, the term λz1âŠznâŠMz1âŠzn has type Ï. Here we assume that z1âŠz.n do not occur free in M
A Calculus of Looping Sequences with Local Rules
In this paper we present a variant of the Calculus of Looping Sequences (CLS
for short) with global and local rewrite rules. While global rules, as in CLS,
are applied anywhere in a given term, local rules can only be applied in the
compartment on which they are defined. Local rules are dynamic: they can be
added, moved and erased. We enrich the new calculus with a parallel semantics
where a reduction step is lead by any number of global and local rules that
could be performed in parallel. A type system is developed to enforce the
property that a compartment must contain only local rules with specific
features. As a running example we model some interactions happening in a cell
starting from its nucleus and moving towards its mitochondria.Comment: In Proceedings DCM 2011, arXiv:1207.682
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