Free Theorems in Languages with Real-World Programming Features

Free theorems, type-based assertions about functions, have become a prominent reasoning tool in functional programming languages. But their correct application requires a lot of care. Restrictions arise due to features present in implemented such languages, but not in the language free theorems were originally investigated in. This thesis advances the formal theory behind free theorems w.r.t. the application of such theorems in non-strict functional languages such as Haskell. In particular, the impact of general recursion and forced strict evaluation is investigated. As formal ground, we employ different lambda calculi equipped with a denotational semantics. For a language with general recursion, we develop and implement a counterexample generator that tells if and why restrictions on a certain free theorem arise due to general recursion. If a restriction is necessary, the generator provides a counterexample to the unrestricted free theorem. If not, the generator terminates without returning a counterexample. Thus, we may on the one hand enhance the understanding of restrictions and on the other hand point to cases where restrictions are superfluous. For a language with a strictness primitive, we develop a refined type system that allows to localize the impact of forced strict evaluation. Refined typing results in stronger free theorems and therefore increases the value of the theorems. Moreover, we provide a generator for such stronger theorems. Lastly, we broaden the view on the kind of assertions free theorems provide. For a very simple, strict evaluated, calculus, we enrich free theorems by (runtime) efficiency assertions. We apply the theory to several toy examples. Finally, we investigate the performance gain of the foldr/build program transformation. The latter investigation exemplifies the main application of our theory: Free theorems may not only ensure semantic correctness of program transformations, they may also ensure that a program transformation speeds up a program.Freie Theoreme sind typbasierte Aussagen über Funktionen. Sie dienen als beliebtes Hilfsmittel für gleichungsbasiertes Schließen in funktionalen Sprachen. Jedoch erfordert ihre korrekte Verwendung viel Sorgfalt. Bestimmte Sprachkonstrukte in praxisorientierten Programmiersprachen beschränken freie Theoreme. Anfängliche theoretische Arbeiten diskutieren diese Einschränkungen nicht oder nur teilweise, da sie nur einen reduzierten Sprachumfang betrachten. In dieser Arbeit wird die Theorie freier Theoreme weiterentwickelt. Im Vordergrund steht die Verbesserung der Anwendbarkeit solcher Theoreme in praxisorientierten, „nicht-strikt” auswertenden, funktionalen Programmiersprachen, wie Haskell. Dazu ist eine Erweiterung des formalen Fundaments notwendig. Insbesondere werden die Auswirkungen von allgemeiner Rekursion und selektiv strikter Auswertung untersucht. Als Ausgangspunkt für die Untersuchungen dient jeweils ein mit einer denotationellen Semantik ausgestattetes Lambda-Kalkül. Im Falle allgemeiner Rekursion wird ein Gegenbeispielgenerator entwickelt und implementiert. Ziel ist es zu zeigen ob und warum allgemeine Rekursion bestimmte Einschränkungen verursacht. Wird die Notwendigkeit einer Einschränkung festgestellt, liefert der Generator ein Gegenbeispiel zum unbeschränkten Theorem. Sonst terminiert er ohne ein Beispiel zu liefern. Auf der einen Seite erhöht der Generator somit das Verständnis für Beschränkungen. Auf der anderen Seite deutet er an, dass Beschränkungen teils überflüssig sind. Bezüglich selektiv strikter Auswertung wird in dieser Arbeit ein verfeinertes Typsystem entwickelt, das den Einfluss solcher vom Programmierer erzwungener Auswertung auf freie Theoreme lokal begrenzt. Verfeinerte Typen ermöglichen stärkere, und somit für die Anwendung wertvollere, freie Theoreme. Durch einen online verfügbaren Generator stehen die Theoreme faktisch aufwandsfrei zur Verfügung. Abschließend wird der Blick auf die Art von Aussagen, die freie Theoreme liefern können, erweitert. Für ein sehr einfaches, strikt auswertendes, Kalkül werden freie Theoreme mit Aussagen über Programmeffizienz bzgl. der Laufzeit angereichert. Die Anwendbarkeit der Theorie wird an einigen sehr einfachen Beispielen verifiziert. Danach wird die Auswirkung der foldr/build- Programmtransformation auf die Programmlaufzeit betrachtet. Diese Betrachtung steckt das Anwendungsziel ab: Freie Theoreme sollen nicht nur die semantische Korrektheit von Programmtransformationen verifizieren, sie sollen außerdem zeigen, wann Transformationen die Performanz eines Programms erhöhen

Child guidance, dynamic psychology and the psychopathologisation of child-rearing culture (c. 1920-1940):a transnational perspective

The historiography of child guidance has focused primarily on the United States, where it first developed before travelling across the English-speaking world. The rapid expansion of child guidance in the interwar years was enabled by private philanthropy, which provided fellowships to foreign professionals to study in the United States. This article focuses upon the transnational transfer of child guidance, the dynamic psychology on which it was based, and the accompanying psychopathologisation of child-rearing culture to a non-English speaking country, the Netherlands. First, it discusses the development of child guidance and the reception of dynamic psychology in the United States and Britain. Next, it analyses the transfer to the Netherlands. It turns out that the Dutch did not copy the American model, but adapted it to fit their conditions and created a more diverse child guidance landscape, in which educational psychology played a less important role than child psychiatry

The effectiveness of a web-based Dutch parenting program to prevent overweight in children 9–13 years of age:Results of a two-armed cluster randomized controlled trial

INTRODUCTION: Although parental support is an important component in programs designed to prevent overweight in children, current programs pay remarkably little attention to the role of parenting. We therefore developed a web-based parenting program entitled “Making a healthy deal with your child”. This e-learning program can be incorporated into existing overweight prevention programs. The aim of this study was to determine the effectiveness of this e-learning program. MATERIALS AND METHODS: The effectiveness was examined in a two-armed cluster randomized controlled trial. The participants were 475 parent-child dyads of children 9–13 years of age in the Netherlands who participated in an existing schoolclass-based overweight prevention program. At the school grade level, parents were randomly assigned to either the intervention or the control condition. Measurements were taken from both parents and children at baseline, and 5 and 12 months after baseline. Primary outcomes included the child’s dietary and sedentary behavior, and level of physical activity. Secondary outcomes included general parenting style, specific parenting practices, and parental self-efficacy. Linear mixed effects models and generalized linear mixed effects models were conducted in R. RESULTS: Intention-to-treat analyses and completers only revealed no significant effects between the intervention and control condition on energy balance-related behaviors of the child and parenting skills after correction for multiple testing. The parents’ mean satisfaction with the e-learning program (on a 10-point scale) was 7.0±1.1. CONCLUSIONS: Although parents were generally satisfied with the parenting program, following this program had no significant beneficial effects regarding the children’s energy balance-related behaviors or the parenting skills compared to the control condition. This program may be more beneficial if used by high-risk groups (e.g. parents of children with unhealthy energy balance-related behaviors and/or with overweight) compared to the general population, warranting further study

Towards a Differentiated Analysis of Competition of Competition Laws

Can "competition of competition laws" be a feasible concept that should play an important role in an international order for the worldwide protection of competition? We introduce four different types of regulatory competition that allow for a more differentiated analysis of beneficial and deficient effects of competition of competition laws. Our analysis shows that most types of regulatory competition have a rather limited scope for application to competition laws. However, yardstick competition can be very promising and represents a powerful argument against centralisation. An important result of our analysis is that the institutional framework of any competition of competition laws plays a crucial role for its workability.

A Universal Definition of "Domestication" to Unleash Global Animal Welfare Progress

This article proposes to establish a universal definition of the phenomenon of Domestication. Included in this phenomenon are, inter alia, the definitions of tame, domesticated or wild animals. Most of us intuitively think that wild and domesticated animals are easy to differentiate. But when it comes to giving measurable criteria to accurately discriminate species, there is today no consensus nor tool available. It has become a considerable gap considering that nowadays, challenges related to animal matters require international or global solutions which are only implementable through collaborations across the board and at all scales. However, without accurate and common definitions, those collaborations are rendered impossible. In this research, the etymology and definitions of the phenomenon of Domestication are considered, followed by its evolution across the literature. Are then examined the existing lists of domesticated species. Finally, the use of the concept of this phenomenon is looked at in laws at different scales and through international organisations, highlighting important discrepancies or even contradictions. The result of this research is the ascertainment that adopting a universal definition of the phenomenon of Domestication is absolutely paramount in order to progress on all animal-related matters. These observations and sources are then analysed in order to build the final part of this article: a proposal, aiming at giving an example of what the solution could look like.Este artículo propone establecer una definición universal del fenómeno de la domesticación. En este fenómeno se incluyen, entre otras, las definiciones de animales domesticados, domesticados o salvajes. La mayoría de nosotros intuitivamente pensamos que los animales salvajes y domesticados son fáciles de diferenciar. Pero cuando se trata de dar criterios medibles para discriminar con precisión a las especies, hoy no hay consenso ni herramienta disponible. Se ha convertido en una brecha considerable considerando que en la actualidad, los desafíos relacionados con los animales requieren soluciones internacionales o globales que solo se pueden implementar a través de colaboraciones en todos los ámbitos y en todas las escalas. Sin embargo, sin definiciones precisas y comunes, esas colaboraciones son imposibles. En esta investigación, se consideran la etimología y las definiciones del fenómeno de la domesticación, seguidas de su evolución en la literatura. Luego se examinan las listas existentes de especies domesticadas. Finalmente, el uso del concepto de este fenómeno se analiza en leyes a diferentes escalas y a través de organizaciones internacionales, destacando discrepancias importantes o incluso contradicciones. El resultado de esta investigación es la constatación de que adoptar una definición universal del fenómeno de la Domesticación es absolutamente primordial para avanzar en todos los asuntos relacionados con los animales. Estas observaciones y fuentes se analizan para construir la parte final de este artículo: una propuesta, con el objetivo de dar un ejemplo de cómo podría ser la solución

Governing by Algorithm? No Noise and (Potentially) Less Bias

As intuitive statisticians, human beings suffer from identifiable biases—cognitive and otherwise. Human beings can also be “noisy” in the sense that their judgments show unwanted variability. As a result, public institutions, including those that consist of administrative prosecutors and adjudicators, can be biased, noisy, or both. Both bias and noise produce errors. Algorithms eliminate noise, and that is important; to the extent that they do so, they prevent unequal treatment and reduce errors. In addition, algorithms do not use mental shortcuts; they rely on statistical predictors, which means that they can counteract or even eliminate cognitive biases. At the same time, the use of algorithms by administrative agencies raises many legitimate questions and doubts. Among other things, algorithms can encode or perpetuate discrimination, perhaps because their inputs are based on discrimination, or perhaps because what they are asked to predict is infected by discrimination. But if the goal is to eliminate discrimination, properly constructed algorithms nonetheless have a great deal of promise for administrative agencies

Secrecy for Mobile Implementations of Security Protocols

Mobile code technology offers interesting possibilities to the practitioner, but also raises strong concerns about security. One aspect of security is secrecy, the preservation of confidential information. This thesis investigates the modelling, specification and verification of secrecy in mobile applications which access and transmit confidential information through a possibly compromised medium (e.g. the Internet). These applications can be expected to communicate secret information using a security protocol, a mechanism to guarantee that the transmitted data does not reach unauthorized entities. The central idea is therefore to relate the secrecy properties of the application to those of the protocol it implements, through the definition of a ``confidential protocol implementation'' relation. The argument takes an indirect form, showing that a confidential implementation transmits secret data only in the ways indicated by the protocol. We define the implementation relation using labelled transition semantics, bisimulations and relabelling functions. To justify its technical definition, we relate this property to a notion of noninterference for nondeterministic systems derived from Cohen's definition of Selective Independency. We also provide simple and local conditions that greatly simplify its verification, and report on our experiments on an architecture showing how the proposed formulations could be used in practice to enforce secrecy of mobile code

Felony Disenfranchisement Legislation: A Test of the Group Threat Hypothesis

The group threat hypothesis is part of the conflict theoretical perspective, which has been one of the most dominant and useful theories in the fields of criminology and criminal justice for decades. The usefulness of this perspective relates to the understanding it provides of how the law can be used by those in power as a measure of control. The use of law as a method of control has a long history in the US society, and there are many examples from which to pull. This project examines the use of one set of laws, felony disenfranchisement legislation, to determine if these laws can be seen as a method for controlling a subgroup of the population. Historically, felony disenfranchisement legislation has been a part of the American legal system from the founding of this country. While the laws have changed many times, the constant has been an effort to disenfranchise a segment of the population deemed as dangerous and prevent such groups from participating in the political process through their votes. Using data on African American population, arrests, and incarceration, this study tests if the strictness of disenfranchisement legislation is associated with the size of African American population, as well as African American arrest and incarceration rates. Both qualitative and quantitative methods were used to understand the nature of felony disenfranchisement legislation and to determine if disenfranchisement legislation could be used as a tool to control African Americans. The qualitative analysis indicates that African Americans are more impacted by disenfranchisement laws in two regards: the criteria that leads to disenfranchisement and the requirements for vote restoration. However, the research hypotheses are partially supported by quantitative analysis. That is, while results indicate that the proportion of African Americans in a state is correlated to the strictness of a state’s disenfranchisement law, there is no relationship between the arrest and incarceration rates and either the strictness of disenfranchisement legislation or the difficulty of the vote restoration procedures. These results point to limitations of using the group threat hypothesis to understand the relationship between disenfranchisement law and criminal justice operation