Mechanizing type environments in weak HOAS

We provide a paradigmatic case study, about the formalization of System F<:'s type language in the proof assistant Coq. Our approach relies on weak HOAS, for the sake of producing a readable and concise representation of the object language. Actually, we present and discuss two encoding strategies for typing environments which yield a remarkable influence on the whole formalization. Then, on the one hand we develop System F<:'s metatheory, on the other hand we address the equivalence of the two approaches internally to Coq

Ambient Calculus and its Logic in the Calculus of Inductive Constructions

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Plug and Play the Theory of Contexts in Higher-Order Abstract Syntax

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Exploiting news to categorize tweets: Quantifying the impact of different news collections

Short texts, due to their nature which makes them full of abbreviations and new coined acronyms, are not easy to classify. Text enrichment is emerging in the literature as a potentially useful tool. This paper is a part of a longer term research that aims at understanding the effectiveness of tweet enrichment by means of news, instead of the whole web as a knowledge source. Since the choice of a news collection may contribute to produce very different outcomes in the enrichment process, we compare the impact of three features of such collections: volume, variety, and freshness. We show that all three features have a significant impact on categorization accuracy. Copyright \ua9 2016 for the individual papers by the paper's authors

An Open Logical Framework

The LFP Framework is an extension of the Harper-Honsell-Plotkin's Edinburgh Logical Framework LF with external predicates, hence the name Open Logical Framework. This is accomplished by defining lock type constructors, which are a sort of \u25a1-modality constructors, releasing their argument under the condition that a possibly external predicate is satisfied on an appropriate typed judgement. Lock types are defined using the standard pattern of constructive type theory, i.e. via introduction, elimination and equality rules. Using LFP, one can factor out the complexity of encoding specific features of logical systems, which would otherwise be awkwardly encoded in LF, e.g. side-conditions in the application of rules in Modal Logics, and sub-structural rules, as in non-commutative Linear Logic. The idea of LFP is that these conditions need only to be specified, while their verification can be delegated to an external proof engine, in the style of the Poincar Principle or Deduction Modulo. Indeed such paradigms can be adequately formalized in LFP. We investigate and characterize the meta-theoretical properties of the calculus underpinning LFP: strong normalization, confluence and subject reduction. This latter property holds under the assumption that the predicates are well-behaved, i.e. closed under weakening, permutation, substitution and reduction in the arguments. Moreover, we provide a canonical presentation of LFP, based on a suitable extension of the notion of \u3b2\u3b7-long normal form, allowing for smooth formulations of adequacy statements. \ua9 The Author, 2013

Taking Advantage of Cloud Solutions to Balance Requests in an Astrophysical Data Center

A complete astrophysical publishing environment, working as a helper system for an astrophysical data center, requires various components, from custom data back ends up to more or less standardized (e.g. Virtual Observatory driven) front end solutions. Combining this environment into one framework can lead to a potentially non scalable or hardly improvable system. In this contribution we describe what we are planning and developing to take advantage of cloud computing infrastructures and of a modular/distributed component architecture to provide a scalable and maintainable publishing environment at the Italian center for Astronomical Archives (IA2) at the INAF (Italian National Institute for Astrophysics) Astronomical Observatory of Trieste. Using a set of modular services, connected by registered interfaces, we are planning to use automated balancing at the front end to allocate services on demand in a cloud environment and allow generic data access in the back end archive solution

Plugging-in Proof Development Environments using Locks in LF

International audienceWe present two extensions of the LF Constructive Type Theory featuring monadic locks. A lock is a monadic type construct that captures the effect of an external call to an oracle. Such calls are the basic tool for plugging-in, i.e. gluing together, different Type Theories and proof development environments. The oracle can be invoked either to check that a constraint holds or to provide a suitable witness. The systems are presented in the canonical style developed by the "CMU School". The first system, CLLFP , is the canonical version of the system LLFP, presented earlier by the authors. The second system, CLLF P? , features the possibility of invoking the oracle to obtain also a witness satisfying a given constraint. We discuss encodings of Fitch-Prawitz Set theory, call-by-value λ-calculi, systems of Light Linear Logic, and partial functions

Towards a Logical Framework with Intersection and Union Types

International audienceWe present an ongoing implementation of a dependent-type theory (∆-framework) based on the Edinburgh Logical Framework LF, extended with Proof-functional logical connectives such as intersection , union, and strong (or minimal relevant) implication. Proof-functional connectives take into account the shape of logical proofs, thus allowing to reflect polymorphic features of proofs in formulae. This is in contrast to classical Truth-functional connec-tives where the meaning of a compound formula is only dependent on the truth value of its subformulas. Both Logical Frameworks and proof functional logics consider proofs as first class citizens. But they do it differently namely, explicitly in the former while implicitly in the latter. Their combination opens up new possibilites of formal reasoning on proof-theoretic semantics. We provide some examples in the extended type theory and we outline a type checker. The theory of the system is under investigation. Once validated in vitro, the proof-functional type theory can be successfully plugged in existing truth-functional proof assistants

Context Aware Browser

I will present the Context Aware Browser, a novel paradigm for context-aware access to Web contents with mobile devices. The idea is to allow automatic download of Web pages, and even automatic execution of Web applications, on user\u27s own mobile device. The Web resources are not simply pushed on the mobile device; rather, they are selected on the basis of the context the user is in: context data (mainly location, but not only) are used to build a query sent to an external search engine, that selects the most relevant Web content. I will describe the idea, provide some examples, show a video of a recently built prototype, present implementation issues, discuss our specific evaluation methodology and the results, and sketch future work and problems. This is an ongoing project, started about five years ago; it is joint work with the Context Aware and Mobile Systems laboratory (smdc.uniud.it) and the MoBe spinoff (www.mobe.it) at Udine University