Software systems typically contain large APIs that are informally specified and hence easily misused. This paper presents the Sage programming language, which is designed to enforce precise interface specifications in a flexible manner. The Sage type system uses a synthesis of the type Dynamic, first-class types, and arbitrary refinement types. Since type checking for this expressive language i...

We investigate biases in farm-level yield risk analysis caused by data aggregation from the farm-level to regional and national levels using the example of Swiss wheat and barley yields. The estimated yield variability decreases significantly with increasing level of aggregation, with crop yield variability at the farm-level being up to 2.38 times higher than indicated from national data. Our r...

Programming Technology Lab Vrije Universiteit Brussel Pleinlaan 2 1050 Brussels BELGIUM Phone: +32 2 629 3306 Fax: +32 2 629 3525 { tommens | clucas | prsteyae }@vub.ac.be Abstract UML provides little support for modelling reusable specifications and designs. To deal with this problem, we enhance UML with support for reuse and evolution of model components (more specifically, collaborating clas...

The effect of the beam-generated transverse deflecting fields on the emittance of an intense bunch of particles in a high-energy linear accelerator is analyzed in this paper. The equation of motion is solved by a perturbation method for cases of a coasting beam and a uniformly accelerated beam. The results are applied to obtain some design tolerance specifications for the recently proposed SLAC...

Divorce law changes made in the 1970s affected marital formation, dissolution, and bargaining within marriage. By altering the terms of the marital contract these legal changes impacted the incentives for women to enter and remain in the labor force. Whereas earlier work had suggested that the impact of unilateral divorce on female employment depended critically on laws governing property divis...

We study the optimal insurance demand of a riskand ambiguity-averse consumer if contract nonperformance risk is perceived as ambiguous. We find that the consumer’s optimal insurance demand is lower compared to a situation without ambiguity and that his degree of ambiguity aversion is negatively associated with the optimal level of coverage. We also determine sufficient conditions for biased bel...

This paper discusses the calculation of test-cases for interactive systems. A novel approach is presented that treats the problem of test-case synthesis as an abstraction problem. The refinement calculus is used to formulate abstraction rules for calculating correct test-case scenarios from a formal contract. This abstraction calculus results in a synthesis method that, does not need to compute...

A major obstacle facing adoption of formal software verification is the difficulty to track changes in the target code and to accomodate them in specifications and in verification arguments. We introduce abstract method calls, a new verification rule for method calls that can be used in most contract-based verification settings. By combining abstract method calls, structured reuse in specificat...

— We examine the cyclical properties of development aid using bilateral data for 22 donors and 113 recipients during 1970–2005. We find that bilateral aid flows are on average procyclical with respect to the business cycle in both donor and recipient countries. While aid outlays contract sharply during severe downturns in donor countries, they rise steeply when aid-receiving countries experienc...