Basic Action Theory

Action semantics is a semantic description framework with very goodpragmatic properties but until now a rather weak theory for reasoningabout programs. A strong action theory would have a great practicalpotential, as it would facilitate reasoning about the large class ofprogramming languages that can be described in action semantics.This report develops the foundations for a richer action theory, bybringing together concepts and techniques from process theory andfrom work on operational reasoning about functional programs. Semanticpreorders and equivalences in the action semantics setting arestudied and useful operational techniques for establishing contextualequivalences are presented. These techniques are applied to establishequational and inequational action laws and an induction rule

A Complete, Co-Inductive Syntactic Theory of Sequential Control and State

We present a new co-inductive syntactic theory, eager normal form bisimilarity, for the untyped call-by-value lambda calculus extended with continuations and mutable references. We demonstrate that the associated bisimulation proof principle is easy to use and that it is a powerful tool for proving equivalences between recursive imperative higher-order programs. The theory is modular in the sense that eager normal form bisimilarity for each of the calculi extended with continuations and/or mutable references is a fully abstract extension of eager normal form bisimilarity for its sub-calculi. For each calculus, we prove that eager normal form bisimilarity is a congruence and is sound with respect to contextual equivalence. Furthermore, for the calculus with both continuations and mutable references, we show that eager normal form bisimilarity is complete: it coincides with contextual equivalence

Analysis of optical properties of strained semiconductor quantum dots for electromagnetically induced transparency

Using multiband k*p theory we study the size and geometry dependence on the slow light properties of conical semiconductor quantum dots. We find the V-type scheme for electromagnetically induced transparency (EIT) to be most favorable, and identify an optimal height and size for efficient EIT operation. In case of the ladder scheme, the existence of additional dipole allowed intraband transitions along with an almost equidistant energy level spacing adds additional decay pathways, which significantly impairs the EIT effect. We further study the influence of strain and band mixing comparing four different k*p band structure models. In addition to the separation of the heavy and light holes due to the biaxial strain component, we observe a general reduction in the transition strengths due to energy crossings in the valence bands caused by strain and band mixing effects. We furthermore find a non-trivial quantum dot size dependence of the dipole moments directly related to the biaxial strain component. Due to the separation of the heavy and light holes the optical transition strengths between the lower conduction and upper most valence-band states computed using one-band model and eight-band model show general qualitative agreement, with exceptions relevant for EIT operation.Comment: 9 pages, 12 figure

Compilation and Equivalence of Imperative Objects (Revised Report)

We adopt the untyped imperative object calculus of Abadi andCardelli as a minimal setting in which to study problems of compilationand program equivalence that arise when compiling object orientedlanguages. We present both a big-step and a small-stepsubstitution-based operational semantics for the calculus. Our firsttwo results are theorems asserting the equivalence of our substitution based semantics with a closure-based semantics like that given by Abadi and Cardelli. Our third result is a direct proof of the correctness of compilation to a stack-based abstract machine via a small-step decompilation algorithm. Our fourth result is that contextual equivalence of objects coincides with a form of Mason and Talcott's CIUequivalence; the latter provides a tractable means of establishing operational equivalences. Finally, we prove correct an algorithm, used inour prototype compiler, for statically resolving method offsets. This isthe first study of correctness of an object-oriented abstract machine,and of operational equivalence for the imperative object calculus

Veterinarians’ role in clients’ decision‑making regarding seriously ill companion animal patients

BACKGROUND: When companion animals become seriously ill clients may have doubts about treatment choices, if any, and turn to veterinarians for help. But how should veterinarians reply? Influence on clients’ decision-making may or may not be acceptable—depending on one’s attitude to principles such as ‘paternalism’, ‘respect for autonomy’ and ‘shared decision-making’. This study takes as a starting point a situation where the animal is chronically ill, or aged, with potentially reduced animal welfare and client quality of life, and thus where clients need to consider treatment options or euthanasia. It is assumed throughout that both veterinarians and clients have the animals’ best interest at heart. The purpose of the study was to explore the challenges these situations hold and to investigate how clients experience veterinary influence. A second aim was to reflect on the ethical implications of the role of veterinarians in these situations. Qualitative interviews were conducted with 12 dog owners considering treatment or euthanasia of their chronically ill or aged dogs. RESULTS: Challenges relating to the dog and to the client were identified. Some situations left the interviewees hesitant, e.g. if lacking a clear cut-off point, the dog appeared normal, the interviewee felt uncertain about treatments or animal welfare, or experienced conflicting concerns. Some interviewees found that veterinarians could influence their decisions. Such influence was received in different ways by the interviewees. Some interviewees wanted active involvement of the veterinarian in the decision-making process, and this may challenge a veterinarian’s wish to respect client autonomy. CONCLUSIONS: Different preferences are likely to exist amongst both veterinarians and clients about veterinary involvement in clients’ decision-making, and such preferences may vary according to the situation. It is suggested, that one way to handle this challenge is to include respect for client preference on veterinary involvement under a wider understanding of respect for autonomy, and to apply models of shared decision-making to veterinary practice. In any case there is a need to further explore the challenges these situations raise, and for the veterinary profession to engage in more formal and structured deliberation over the role of veterinarians in relation to clients’ decision-making. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s13028-016-0211-x) contains supplementary material, which is available to authorized users