Improvements for Free

"Theorems for Free!" (Wadler, FPCA 1989) is a slogan for a technique that allows to derive statements about functions just from their types. So far, the statements considered have always had a purely extensional flavor: statements relating the value semantics of program expressions, but not statements relating their runtime (or other) cost. Here we study an extension of the technique that allows precisely statements of the latter flavor, by deriving quantitative theorems for free. After developing the theory, we walk through a number of example derivations. Probably none of the statements derived in those simple examples will be particularly surprising to most readers, but what is maybe surprising, and at the very least novel, is that there is a general technique for obtaining such results on a quantitative level in a principled way. Moreover, there is good potential to bring that technique to bear on more complex examples as well. We turn our attention to short-cut fusion (Gill et al., FPCA 1993) in particular.Comment: In Proceedings QAPL 2011, arXiv:1107.074

Deployment Prior Injection for Run-time Calibratable Object Detection

With a strong alignment between the training and test distributions, object relation as a context prior facilitates object detection. Yet, it turns into a harmful but inevitable training set bias upon test distributions that shift differently across space and time. Nevertheless, the existing detectors cannot incorporate deployment context prior during the test phase without parameter update. Such kind of capability requires the model to explicitly learn disentangled representations with respect to context prior. To achieve this, we introduce an additional graph input to the detector, where the graph represents the deployment context prior, and its edge values represent object relations. Then, the detector behavior is trained to bound to the graph with a modified training objective. As a result, during the test phase, any suitable deployment context prior can be injected into the detector via graph edits, hence calibrating, or "re-biasing" the detector towards the given prior at run-time without parameter update. Even if the deployment prior is unknown, the detector can self-calibrate using deployment prior approximated using its own predictions. Comprehensive experimental results on the COCO dataset, as well as cross-dataset testing on the Objects365 dataset, demonstrate the effectiveness of the run-time calibratable detector

Greater Manchester green deal communities programme scheme exit paper

The report provides GM Local Authorities with an update on the Greater Manchester Green Deal Communities Programme and with relevant reference details for post programme

Copyleft vs copyright: some competitive effects of Open Source

In this paper, we study oligopolistic competition between closed and open source softwares. By intersecting existing economic contributions on open source, we propose a two stage game with perfect information and product differetiation in which producers firstly set software's quality, then they determine prices (constrained at zero for open source programs). In doing this, we explicitly model lock-in effects, network externality components' of software quality as well as knowledge accumulation in software use and implementation. With respect to a monopolistic benchmark case, we argue that in duopoly a pro- prietary sofware producer facing an open source software will reduce its selling price whether: (i) its network of users is larger than open source's one and its consumers are largely experienced on its program, (ii) it has a small network of un-skilled consumers. In opposition, after open source software's emergence, proprietary software price does augment if proprietary software users form a large, but poorly skilled network. Fur- thermore, we show that, in all above cases, proprietary software quality increases because of the existence of a open source alternative to a previouisly monopolistic program. Finally, by modeling knowledge accumulation processes through difference equa- tions, we show that the ratio between closed and open source programs' opportunity costs of software learning and deployment plays a crucial role in shaping market out- comes. Until an open source software remains too complex and technical for unskilled or time-scarse users, a shared market solution in which both softwares are adopted is predicted. In contrast, if opportunity costs in learning and understanding open source programs are remarkably low, or at least equal to opportunity costs of a closed source software, then a open source dominance outcome (i.e. all software are open ones) phases out

Programs for cheap!

Write down the definition of a recursion operator on a piece of paper. Tell me its type, but be careful not to let me see the operator’s definition. I will tell you an optimization theorem that the operator satisfies. As an added bonus, I will also give you a proof of correctness for the optimisation, along with a formal guarantee about its effect on performance. The purpose of this paper is to explain these tricks

Parametric polymorphism and operational improvement

Parametricity, in both operational and denotational forms, has long been a useful tool for reasoning about program correctness. However, there is as yet no comparable technique for reasoning about program improvement, that is, when one program uses fewer resources than another. Existing theories of parametricity cannot be used to address this problem as they are agnostic with regard to resource usage. This article addresses this problem by presenting a new operational theory of parametricity that is sensitive to time costs, which can be used to reason about time improvement properties. We demonstrate the applicability of our theory by showing how it can be used to prove that a number of well-known program fusion techniques are time improvements, including fixed point fusion, map fusion and short cut fusion

“Directing the Upcoming Generation’s Mind in the Right Direction”: Enslaved Children in the French Emancipation Project in Martinique, 1835-1848

Enslaved children were at the centre of France’s reform of colonial slavery from the mid-1830s to 1848. Youths, because of their malleability and supposed innocence, were deemed most deserving of moralizing efforts through religious and elementary education. When emancipation was conceivable by many on both sides of the Atlantic, enslaved children came to represent the future generation of French colonial citizens. Although slaveholders strongly opposed abolitionists’ efforts and despite the slow nature of metropolitan reforms, hundreds of enslaved children in Martinique benefitted from the rights they acquired in the last decade and a half of slavery, namely, partial access to religious and elementary education, family rights, and freedom.Les enfants esclaves furent au cœur de la réforme de l’esclavage dans les colonies menée par la France du milieu des années 1830 à 1848. On estimait que les jeunes, vu leur malléabilité et leur supposée innocence, méritaient le plus d’être moralisés grâce à l’enseignement religieux et à l’enseignement primaire. Une fois l’émancipation devenue envisageable par nombre de personnes de part et d’autre de l’Atlantique, on en vint à considérer les enfants esclaves comme la future génération de citoyens français des colonies. Bien que les propriétaires d’esclaves aient été fortement opposés aux efforts des abolitionnistes et malgré la lenteur des réformes métropolitaines, des centaines d’enfants esclaves de Martinique bénéficièrent des droits acquis pendant les quinze dernières années de l’esclavage, soit l’accès partiel à l’enseignement religieux et à l’enseignement primaire, les droits des familles et la liberté

The Geologic Strata of the Law School Curriculum

The modest aim of this piece is to supply some historical background to the other contributions to this Symposium. The modern American law school curriculum is the product of a few but critical choices of design, some of them over a century old. In this Article, I seek to (1) outline how the basic structure and content of the modern American law school curriculum came into being and what were the main competitors that curriculum displaced; (2) describe some of the ways in which the curriculum\u27s basic structure and content have changed since its inception; and (3) point to some of the main sources and motors of change

The Geologic Strata of the Law School Curriculum

The modest aim of this piece is to supply some historical background to the other contributions to this Symposium. The modern American law school curriculum is the product of a few but critical choices of design, some of them over a century old. In this Article, I seek to (1) outline how the basic structure and content of the modern American law school curriculum came into being and what were the main competitors that curriculum displaced; (2) describe some of the ways in which the curriculum\u27s basic structure and content have changed since its inception; and (3) point to some of the main sources and motors of change. ORIGINS OF THE BASIC STRUCTURE AND CONTENT OF THE MODERN AMERICAN LAW SCHOOL CURRICULUM The American law school-in the basic shape we recognize it today-originated with the model of legal education that President Charles W. Eliot and Dean Christopher Columbus Langdell established at Harvard in 1870. At first, Harvard\u27s model seemed as if it might fail: the school had lost enrollments and had to make its way against rival models and hostile critics. By 1900, however, Harvard\u27s success was assured. Its example-sometimes transmitted by Harvard\u27s own former faculty as pro-consular deans, such as William Keener at Columbia and Joseph Beale at Chicago-spread to other leading law schools between 1895 and 1925; and between 1925 and 1950 virtually every full-time university-based law school in the country had adopted the Harvard model\u27s basic elements. This story of convergence on a uniform model is all the more remarkable when one considers that all of these law schools were preparing their students for a wide variety of roles and careers in the United States\u27 highly stratified and segmented legal profession. A. The Bedrock: The Harvard Template and Its Rivals In the period of its adoption, Harvard\u27s model was distinctive in both structure and content