System F with Constraint Types

System F is a type system that can be seen as both a proof system for second-order propositional logic and as a polymorphic programming language. In this work we explore several extensions of System F by types which express subtyping constraints. These systems include terms which represent proofs of subtyping relationships between types. Given a proof that one type is a subtype of another, one may use a coercion term constructor to coerce terms from the first type to the second. The ability to manipulate type constraints as first-class entities gives these systems a lot of expressive power, including the ability to encode generalized algebraic data types and intensional type analysis. The main contributions of this work are in the formulation of constraint types and a proof of strong normalization for an extension of System F with constraint types

A formally verified proof of the prime number theorem

The prime number theorem, established by Hadamard and de la Vall'ee Poussin independently in 1896, asserts that the density of primes in the positive integers is asymptotic to 1 / ln x. Whereas their proofs made serious use of the methods of complex analysis, elementary proofs were provided by Selberg and Erd"os in 1948. We describe a formally verified version of Selberg's proof, obtained using the Isabelle proof assistant.Comment: 23 page

Forest tree marginal populations in Europe - report on the state of knowledge on forest tree marginal and peripheral populations in Europe

Marginal/peripheral (MaP) forest populations exist at the edge of species ranges, and may contain unique genetic diversity arising from adaptation to the adverse and unusual in the regions which they inhabit. The effects of climatic and other global changes are likely to be increasingly significant, and will affect forest tree species and their marginal populations. Studying adaptive processes in MaP populations is crucial and of mutual interest for European and non-European countries to understanding the evolution of species, and for the development of forest genetic resources (FGR) conservation, management strategies, and networks to cope with global change. These populations are threatened not only by global warming, but by various other threats arising from human activities. Because of their millennia-long history of adaptation to environmental changes, FGR growing in Europe may prove invaluable for adapting the forestry sector

Using constraint grammar in the Bangor Autoglosser to disambiguate multilingual spoken text

Proceedings of the NODALIDA 2011 Workshop Constraint Grammar Applications. Editors: Eckhard Bick, Kristin Hagen, Kaili Müürisep, Trond Trosterud. NEALT Proceedings Series, Vol. 14 (2011), 17–25. © 2011 The editors and contributors. Published by Northern European Association for Language Technology (NEALT) http://omilia.uio.no/nealt . Electronically published at Tartu University Library (Estonia) http://hdl.handle.net/10062/19231

The Lessons of “Lesson Drawing”: How the Obama Administration Attempted to Learn from Failure of the Clinton Health Plan

The article examines the role of historical insights in the creation of U.S. healthcare policy. Particular focus is given to the influence of former U.S. President Bill Clinton\u27s 1993-1994 attempts at healthcare reform on the policies of U.S. President Barack Obama. It is suggested that while the U.S. Patient Protection and Affordable Care act of 2010 was successful in many respects, the Obama administration\u27s efforts to avoid missteps taken with Clinton\u27s Health Security Act did not significantly aid and sometimes even hindered its progress. Details on the political strategy, policy design, and political rhetoric used by both administrations are presented. Other topics include partisan politics and the communication of policy goals to the public

Novel Approaches to Optimise Early Growth in Willow Crops

peer-reviewedWillow is a fast growing, high yielding biomass crop that can help reduce reliance on fossil fuels. However, long establishment times to get to profitability and sustainable yield may deter interest in planting the crop. A number of different approaches were investigated to optimise and accelerate early growth. These approaches were water immersion, plastic application, altering stem orientation at planting, altering coppicing timings and applying growth hormone. Glasshouse and field trials were used to test the different approaches. In this work, planting material was soaked for a varying number of days and plastic was applied or not applied in field trials. In the planting orientation approach, stems were planted diagonally or vertically with half of the planting material above the ground level or horizontally below ground level. Additionally, willow crops were coppiced at different times throughout their first growing season and a growth hormone trial was also incorporated in this work. Water soaking, plastic application, coppicing during the growing season or hormone application did not improve early growth or yield. However, early growth and yield were increased by manipulating the planting orientation of willow stems. Planting orientation treatments in which part of the stem was left above the ground increased early growth and yield significantly compared to the control without requiring extra inputs at planting. The beneficial effects of coppicing can be achieved by manipulating the planting procedure so that the first year’s growth is not disregarded

Molecular and adaptive variation in the Caledonian Pine, Pinus sylvestris (L.)

The remnants of the Caledonian Pine Forest represent the north western boundary of the Eurasian Pinus sylvestris (L.) distribution. Remnant populations occupy a diverse range of environments within Scotland, subject to a steep rainfall gradient, and previous investigations have found evidence of local adaptation. Additionally, studies of biochemical and molecular markers have indicated that Scotland’s native pinewoods originated from more than one glacial refugium. Whole-genome-shotgun (WGS) sequencing was employed for the discovery of mitochondrial (mt) variants that may provide further insight into the origins of P. sylvestris populations both in Scotland and mainland Europe. DNA extractions were performed on megagametophyte tissue from Scottish, Finnish, and Spanish populations. Three members of the closely related P. mugo species complex were also sequenced. Using similarity-based approach, 160kbp of putative mitochondrial sequence was recovered by comparison of de novo assembled contigs with the mtgenome of the gymnosperm Cycas taitungensis. In total, 16 novel variants were identified among samples, which may be used in future phylogeographic studies. A study of needle characters was performed for eight native populations of P. sylvestris in an outdoor provenance/progeny trial of 192 saplings. A negative correlation was detected between longitude and the number of stomatal rows present on needle surfaces. It was posited that this may be an adaptive response to lower water availability in eastern pinewoods, possibly in conjunction with increasing altitude. The west coast of Scotland is one of the wettest regions in Europe: western pinewoods may receive in excess of 3,000mm of rainfall in a year, compared with an average of 800mm eastern sites. To determine whether native pinewoods are differentially adapted to waterlogging, a glasshouse based provenance/progeny trial of 432 saplings from nine native populations was undertaken, in which 50% were subject to a long-term waterlogging treatment, and the remainder used as a control. Two studies were then conducted. In the first, responses to the treatment were assessed in terms of phenological and growth traits. Bud flush was delayed in response to waterlogging, and growth was impeded relative to the control. Although population differences were observed, treatment × population interactions were not detected. In the second study physiological traits known to be sensitive to plant stress and water balance were measured at intervals throughout the experiment. Prior to the commencement of the treatment needle δ13C was found to exhibit interpopulation differentiation, and was positively correlated with longitude. This seems likely to represent differential selection for water use efficiency between eastern and western pinewoods. Photochemical efficiency and stomatal conductance were found to be reduced by waterlogging, and needle δ13C was increased. After generalising populations into ‘high’ and ‘low’ rainfall groups (monthly averages of 214.9mm and 72.8mm, respectively), high rainfall populations were observed to maintain consistently higher photochemical efficiency under waterlogging the low rainfall populations. In addition, the low rainfall group exhibited greater variability in response to flooding (in terms of phenotypic and additive genetic variance) which may be indicative of a lack of past selection pressure