Steinness of bundles with fiber a Reinhardt bounded domain

Let E denote a bundle with fiber D and with basis B. Both D and B are assumed to be Stein. For D a Reinhardt bounded domain of dimension d=2 or 3, we give a necessary and sufficient condition on D for the existence of a non-Stein such E (Theorem 1); for d=2, we give necessary and sufficient criteria for E to be Stein (Theorem 2). For D a Reinhardt bounded domain of any dimension not intersecting any coordinate hyperplane, we give a sufficient criterion for E to be Stein (Theorem 3).Comment: To appear in Bull. Soc. Math. Franc

A remark on the Hard Lefschetz Theorem for K\"ahler orbifolds

We give a proof of the hard Lefschetz theorem for orbifolds that does not involve intersection homology. This answers a question of Fulton. We use a foliated version of the hard Lefschetz theorem due to El Kacimi

Foliations modeling nonrational simplicial toric varieties

We establish a correspondence between simplicial fans, not necessarily rational, and certain foliated compact complex manifolds called LVMB-manifolds. In the rational case, Meersseman and Verjovsky have shown that the leaf space is the usual toric variety. We compute the basic Betti numbers of the foliation for shellable fans. When the fan is in particular polytopal, we prove that the basic cohomology of the foliation is generated in degree two. We give evidence that the rich interplay between convex and algebraic geometries embodied by toric varieties carries over to our nonrational construction. In fact, our approach unifies rational and nonrational cases.Comment: 24 pages, 4 figures, expository changes, references updated. Link to the journal http://j.mp/BatZaf; Int. Math. Res. Not. 2015 (Published online February 24, 2015

Scalable visualisation methods for modern Generalized Additive Models

In the last two decades the growth of computational resources has made it possible to handle Generalized Additive Models (GAMs) that formerly were too costly for serious applications. However, the growth in model complexity has not been matched by improved visualisations for model development and results presentation. Motivated by an industrial application in electricity load forecasting, we identify the areas where the lack of modern visualisation tools for GAMs is particularly severe, and we address the shortcomings of existing methods by proposing a set of visual tools that a) are fast enough for interactive use, b) exploit the additive structure of GAMs, c) scale to large data sets and d) can be used in conjunction with a wide range of response distributions. All the new visual methods proposed in this work are implemented by the mgcViz R package, which can be found on the Comprehensive R Archive Network

L'éthique à l'écran. Compte-rendu de What's Good on TV? – Understanding Ethics Through Television, de Jamie Watson et Robert Arp, et de Seeing the Light – Exploring Ethics Through Movies, de Wanday Teays

Compte-rendu / ReviewWhat's Good on TV ? – Understanding Ethics Through Television de Jamie Watson et Robert Arp, et Seeing the Light - Exploring Ethics Through Movies de Wanday Teays, entreprennent chacun à sa manière de montrer l'intérêt des fictions audiovisuelles – télévisées et cinématographiques – pour enseigner l'éthique.What’s Good on TV ? – Understanding Ethics Through Television by Jamie Watson and Robert Arp, and Seeing the Light – Exploring Ethics Through Movies by Wanday Teays, undertake each in their own way to show the interest of audiovisual fictions – film and television – for teaching ethics

The down side of choice : having a choice benefits enjoyment but at a cost to efficiency and time in visual search

The efficiency of how people search for an item in visual search has, traditionally, been thought to depend on bottom-up or top-down guidance cues. However, recent research has shown that the rate people visually search through a display is also affected by cognitive strategies. This paper investigates the role of choice in visual search, by asking whether giving people a choice alters both preference for a cognitively neutral task and search behaviour. Two visual search conditions were examined: one where participants were given a choice of visual search task (the Choice condition) and one where participants did not have a choice (the No Choice condition). The results found that participants in the Choice condition rated the task as both more enjoyable and likeable than participants in the No Choice condition. However, despite their preferences, actual search performance in the Choice condition was slower and less efficient compared to the No Choice condition (Experiment 1). Experiment 2 showed that the difference in search performance between the Choice and No Choice conditions disappeared when central executive processes became occupied with a task-switching task. The data concur with a choice impaired hypothesis of search where having a choice leads to more motivated, active search involving executive processes

Fast calibrated additive quantile regression

We propose a novel framework for fitting additive quantile regression models, which provides well calibrated inference about the conditional quantiles and fast automatic estimation of the smoothing parameters, for model structures as diverse as those usable with distributional GAMs, while maintaining equivalent numerical efficiency and stability. The proposed methods are at once statistically rigorous and computationally efficient, because they are based on the general belief updating framework of Bissiri et al. (2016) to loss based inference, but compute by adapting the stable fitting methods of Wood et al. (2016). We show how the pinball loss is statistically suboptimal relative to a novel smooth generalisation, which also gives access to fast estimation methods. Further, we provide a novel calibration method for efficiently selecting the 'learning rate' balancing the loss with the smoothing priors during inference, thereby obtaining reliable quantile uncertainty estimates. Our work was motivated by a probabilistic electricity load forecasting application, used here to demonstrate the proposed approach. The methods described here are implemented by the qgam R package, available on the Comprehensive R Archive Network (CRAN)

Holomorphic flexibility properties of compact complex surfaces

We introduce the notion of a stratified Oka manifold and prove that such a manifold $X$ is strongly dominable in the sense that for every $x\in X$, there is a holomorphic map f:\C^n\to X, $n=\dim X$, such that $f(0)=x$ and $f$ is a local biholomorphism at 0. We deduce that every Kummer surface is strongly dominable. We determine which minimal compact complex surfaces of class VII are Oka, assuming the global spherical shell conjecture. We deduce that the Oka property and several weaker holomorphic flexibility properties are in general not closed in families of compact complex manifolds. Finally, we consider the behaviour of the Oka property under blowing up and blowing down.Comment: Version 2: Theorem 11 reformulated and its proof corrected. Minor improvements to the exposition. Version 3: A few minor improvements. To appear in International Mathematics Research Notice