22,161 research outputs found
Probabilistic call by push value
We introduce a probabilistic extension of Levy's Call-By-Push-Value. This
extension consists simply in adding a " flipping coin " boolean closed atomic
expression. This language can be understood as a major generalization of
Scott's PCF encompassing both call-by-name and call-by-value and featuring
recursive (possibly lazy) data types. We interpret the language in the
previously introduced denotational model of probabilistic coherence spaces, a
categorical model of full classical Linear Logic, interpreting data types as
coalgebras for the resource comonad. We prove adequacy and full abstraction,
generalizing earlier results to a much more realistic and powerful programming
language
Rapid recreation assessment: a tool to assess visitor use and associated impacts at coastal and marine protected areas
As more people discover coastal and marine protected areas as destinations for leisure-time pursuits, the task of managing coastal resources while providing opportunities for high quality visitor experiences becomes more challenging. Many human impacts occur at these sites; some are caused by recreation and leisure activities on-site, and others by activities such as agriculture, aquaculture, or residential and economic development in surrounding
areas. Coastal management professionals are continually looking for effective ways to prevent or mitigate negative impacts of visitor use. (PDF contains 8 pages)
Most coastal and marine protected area managers are
challenged with balancing two competing goals—protection of natural and cultural resources and provision of opportunities for public use. In most cases, some level of compromise between the goals is necessary, where one goal constrains or “outweighs” the other. Often there is a lack of clear agreement about the priority of these competing goals. Consequently, while natural resource decisions
should ultimately be science-based and objective, such decisions are frequently made under uncertainty, relying heavily upon professional judgment. These decisions are subject to a complex array of formal and informal drivers and constraints—data availability, timing, legal mandate, political will, diverse public opinion, and physical, human, and social capital. This paper highlights assessment,
monitoring, and planning approaches useful to gauge existing resource and social conditions, determine
feasibility of management actions, and record decision process steps to enhance defensibility. Examples are presented from pilot efforts conducted at the Rookery Bay National Estuarine Research Reserve (NERR) and Ten Thousand Islands National Wildlife Refuge (NWR) in South Florida
Prebisch-Singer: Debates, Growth Model and Estimates
Prebisch and Singer (henceforth PS) have initiated several debates in economics, which have generated much research. Some of these debates may have converged to a compromise, whereas others are much less researched. We briefly summarize them in the next section in order to point out that the implications for growth theory have been largely neglected. Then we will present a growth model and estimate which show that income and price elasticities matter for long-run growth.Economics ;
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Promoting environmentally sustainable enterprises: some policy options
Governments around the world are taking an increasing interest in promoting environmentally-sustainable economic activity. They have developed a variety of policy approaches in an effort to address environmental issues that range from localised pollution incidents to global climate change. This chapter examines the kinds of intervention tools that are being used to improve the environmental performance of SMEs, and to guide entrepreneurial energies towards more environmentally-benign goals. The chapter aims to: (1) outline the main options available to policy-makers; (2) compare specific intervention tools, noting their strengths and limitations; and (3) discuss the case for adopting more holistic approaches to address the pervasive, complex and often deeply-rooted challenges of sustainable development. Key lessons are that policy makers need to select appropriate combinations of tools based on careful reviews of the evidence, and that well-integrated, context-sensitive policies are likely to prove the most effective
Simultaneous Estimation of Income and Price Elasticities of Export Demand, Scale Economies and Total Factor Productivity Growth for Brazil
This paper focuses on a model in which low (high) export demand elasticities and the fact that developing countries are importers of capital goods help explaining the slow (high) growth of these countries. The question arises whether export demand elasticities are low or high. For answering this question, export demand elasticities for the case of Brazil are estimated using a growth model. As a by-product of estimating the model, we obtain estimates for total-factor productivity growth and for scale economies. Based on the results from estimation we calculate steady-state growth rates, engine and handmaiden effects of growth as well as dynamic steady-state gains from trade. The model and the results are discussed in regard to several strands of literature.international economics and trade ;
Full abstraction for probabilistic PCF
We present a probabilistic version of PCF, a well-known simply typed
universal functional language. The type hierarchy is based on a single ground
type of natural numbers. Even if the language is globally call-by-name, we
allow a call-by-value evaluation for ground type arguments in order to provide
the language with a suitable algorithmic expressiveness. We describe a
denotational semantics based on probabilistic coherence spaces, a model of
classical Linear Logic developed in previous works. We prove an adequacy and an
equational full abstraction theorem showing that equality in the model
coincides with a natural notion of observational equivalence
Measurable Cones and Stable, Measurable Functions
We define a notion of stable and measurable map between cones endowed with
measurability tests and show that it forms a cpo-enriched cartesian closed
category. This category gives a denotational model of an extension of PCF
supporting the main primitives of probabilistic functional programming, like
continuous and discrete probabilistic distributions, sampling, conditioning and
full recursion. We prove the soundness and adequacy of this model with respect
to a call-by-name operational semantics and give some examples of its
denotations
Testing uniformity on high-dimensional spheres against monotone rotationally symmetric alternatives
We consider the problem of testing uniformity on high-dimensional unit
spheres. We are primarily interested in non-null issues. We show that
rotationally symmetric alternatives lead to two Local Asymptotic Normality
(LAN) structures. The first one is for fixed modal location and allows
to derive locally asymptotically most powerful tests under specified .
The second one, that addresses the Fisher-von Mises-Langevin (FvML) case,
relates to the unspecified- problem and shows that the high-dimensional
Rayleigh test is locally asymptotically most powerful invariant. Under mild
assumptions, we derive the asymptotic non-null distribution of this test, which
allows to extend away from the FvML case the asymptotic powers obtained there
from Le Cam's third lemma. Throughout, we allow the dimension to go to
infinity in an arbitrary way as a function of the sample size . Some of our
results also strengthen the local optimality properties of the Rayleigh test in
low dimensions. We perform a Monte Carlo study to illustrate our asymptotic
results. Finally, we treat an application related to testing for sphericity in
high dimensions
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