52 research outputs found
Knowledge Spaces and the Completeness of Learning Strategies
We propose a theory of learning aimed to formalize some ideas underlying
Coquand's game semantics and Krivine's realizability of classical logic. We
introduce a notion of knowledge state together with a new topology, capturing
finite positive and negative information that guides a learning strategy. We
use a leading example to illustrate how non-constructive proofs lead to
continuous and effective learning strategies over knowledge spaces, and prove
that our learning semantics is sound and complete w.r.t. classical truth, as it
is the case for Coquand's and Krivine's approaches
Orchestrated Session Compliance
We investigate the notion of orchestrated compliance for client/server
interactions in the context of session contracts. Devising the notion of
orchestrator in such a context makes it possible to have orchestrators with
unbounded buffering capabilities and at the same time to guarantee any message
from the client to be eventually delivered by the orchestrator to the server,
while preventing the server from sending messages which are kept indefinitely
inside the orchestrator. The compliance relation is shown to be decidable by
means of 1) a procedure synthesising the orchestrators, if any, making a client
compliant with a server, and 2) a procedure for deciding whether an
orchestrator behaves in a proper way as mentioned before.Comment: In Proceedings ICE 2015, arXiv:1508.0459
Type Assignement for Mobile Objects
Digitalitzat per Artypla
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
Characterisation of Strongly Normalising lambda-mu-Terms
We provide a characterisation of strongly normalising terms of the
lambda-mu-calculus by means of a type system that uses intersection and product
types. The presence of the latter and a restricted use of the type omega enable
us to represent the particular notion of continuation used in the literature
for the definition of semantics for the lambda-mu-calculus. This makes it
possible to lift the well-known characterisation property for
strongly-normalising lambda-terms - that uses intersection types - to the
lambda-mu-calculus. From this result an alternative proof of strong
normalisation for terms typeable in Parigot's propositional logical system
follows, by means of an interpretation of that system into ours.Comment: In Proceedings ITRS 2012, arXiv:1307.784
Logical equivalence for subtyping object and recursive types
Subtyping in first order object calculi is studied with respect to the logical semantics obtained by identifying terms that satisfy the same set of predicates, as formalised through an assignment system. It is shown that equality in the full first order -calculus is modelled by this notion, which in turn is included in a Morris-style contextual equivalence
Intersection Types for the Computational lambda-Calculus
We study polymorphic type assignment systems for untyped lambda-calculi with
effects, based on Moggi's monadic approach. Moving from the abstract definition
of monads, we introduce a version of the call-by-value computational
lambda-calculus based on Wadler's variant with unit and bind combinators, and
without let. We define a notion of reduction for the calculus and prove it
confluent, and also we relate our calculus to the original work by Moggi
showing that his untyped metalanguage can be interpreted and simulated in our
calculus. We then introduce an intersection type system inspired to Barendregt,
Coppo and Dezani system for ordinary untyped lambda-calculus, establishing type
invariance under conversion, and provide models of the calculus via inverse
limit and filter model constructions and relate them. We prove soundness and
completeness of the type system, together with subject reduction and expansion
properties. Finally, we introduce a notion of convergence, which is precisely
related to reduction, and characterize convergent terms via their types
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