Statman′s 1-Section Theorem

AbstractStatman′s 1-Section Theorem (Statman, 1985a, in "Harvey Friedman′s Research on the Foundations of Mathematics" ( L. Harrington et al., Eds.), pp. 331-338, North-Holland, Amsterdam) is an important but little-known result in the model theory of the simply typed λ-calculus. The 1-Section Theorem states a necessary and sufficient condition on models of the simply-typed λ-calculus for determining whether βη-equational reasoning is complete for proving equations that hold in a model. We review the statement of the theorem, give a detailed proof, and discuss its significance

Types for Flexible Objects

Abstract. Scripting languages are popular in part due to their ex-tremely flexible objects. Features such as dynamic extension, mixins, and first-class messages improve programmability and lead to concise code. But attempts to statically type these features have met with lim-ited success. Here we present TinyBang, a small typed language in which flexible object operations can be encoded. We illustrate this flexibility by solving an open problem in OO literature: we give an encoding where objects can be extended after being messaged without compromising the expressiveness of subtyping. TinyBang’s subtype constraint system en-sures that all types are completely inferred; there are no data declarations or type annotations. We formalize TinyBang and prove the type system is sound and decidable; all examples in the paper run in our most recent implementation.

Safe Object Composition in the Presence of Subtyping

Abstract. Object composition arises as a natural operation to combine objects in an object-based setting. In our incomplete objects setting it has a strong meaning, as it may combine objects with different internal states. In this paper we study how to make object composition safe in the presence of width subtyping, we propose two solutions, and discuss the alternative ones.

Effect of the antihepcidin Spiegelmer lexaptepid on inflammation-induced decrease in serum iron in humans

Contains fulltext : 136275.pdf (publisher's version ) (Closed access)Increased hepcidin production is key to the development of anemia of inflammation. We investigated whether lexaptepid, an antihepcidin l-oligoribonucleotide, prevents the decrease in serum iron during experimental human endotoxemia. This randomized, double-blind, placebo-controlled trial was carried out in 24 healthy males. At T = 0 hours, 2 ng/kg Escherichia coli lipopolysaccharide was intravenously administered, followed by an intravenous injection of 1.2 mg/kg lexaptepid or placebo at T = 0.5 hours. The lipopolysaccharide-induced inflammatory response was similar in subjects treated with lexaptepid or placebo regarding clinical and biochemical parameters. At T = 9 hours, serum iron had increased by 15.9 +/- 9.8 micromol/L from baseline in lexaptepid-treated subjects compared with a decrease of 8.3 +/- 9.0 micromol/L in controls (P < .0001). This study delivers proof of concept that lexaptepid achieves clinically relevant hepcidin inhibition enabling investigations in the treatment of anemia of inflammation. This trial was registered at www.clinicaltrial.gov as #NCT01522794

A Lambda Calculus of Objects with Self-Inflicted Extension

In this paper we investigate, in the context of functional prototype-based languages, objects which might extend themselves upon receiving a message. The possibility for an object of extending its own \self&quot;, referred to by Cardelli, as a self-inicted operation, is novel in the context of typed object-based languages. We present a sound type system for this calculus which guarantees that evaluating a welltyped expression will never yield a message-not-found runtime error. We give several examples which illustrate the increased expressive power of our system with respect to existing calculi of objects. The new type system allows also for a exible width-subtyping, still permitting sound method override, and a limited form of object extension. The resulting calculus appears to be a good starting point for a rigorous mathematical analysis of class-based languages.

Program logics for sequential higher-order control

We introduce a Hoare logic for call-by-value higher-order functional languages with control operators such as callcc. The key idea is to build the assertion language and proof rules around an explicit logical representation of jumps and their dual 'places-to-jump-to'. This enables the assertion language to capture precisely the intensional and extensional effects of jumping by internalising rely/guarantee reasoning, leading to simple proof rules for higher-order functions with callcc. We show that the logic can reason easily about non-trivial uses of callcc. The logic matches exactly with the operational semantics of the target language (observational completeness), is relatively complete in Cook's sense and allows efficient generation of characteristic formulae