Finitely generated soluble groups and their subgroups

We prove that every finitely generated soluble group which is not virtually abelian has a subgroup of one of a small number of types.Comment: 16 page

A unifying representation for a class of dependent random measures

We present a general construction for dependent random measures based on thinning Poisson processes on an augmented space. The framework is not restricted to dependent versions of a specific nonparametric model, but can be applied to all models that can be represented using completely random measures. Several existing dependent random measures can be seen as specific cases of this framework. Interesting properties of the resulting measures are derived and the efficacy of the framework is demonstrated by constructing a covariate-dependent latent feature model and topic model that obtain superior predictive performance

Evolution of community structure in the world trade web

In this note we study the bilateral merchandise trade flows between 186 countries over the 1948-2005 period using data from the International Monetary Fund. We use Pajek to identify network structure and behavior across thresholds and over time. In particular, we focus on the evolution of trade "islands" in the a world trade network in which countries are linked with directed edges weighted according to fraction of total dollars sent from one country to another. We find mixed evidence for globalization.Comment: To be submitted to APFA 6 Proceedings, 8 pages, 3 Figure

Preference for art: similarity, statistics, and selling price

ABSTRACT Factors governing human preference for artwork have long been studied but there remain many holes in our understanding. Bearing in mind contextual factors (both the conditions under which the art is viewed, and the state of knowledge viewers have regarding art) that play some role in preference, we assess in this paper three questions. First, what is the relationship between perceived similarity and preference for different types of art? Second, are we naturally drawn to certain qualities-and perhaps to certain image statistics-in art? And third, do social and economic forces tend to select preferred stimuli, or are these forces governed by non-aesthetic factors such as age, rarity, or artist notoriety? To address the first question, we tested the notion that perceived similarity predicts preference for three classes of paintings: landscape, portrait/still-life, and abstract works. We find that preference is significantly correlated with (a) the first principal component of similarity in abstract works; and (b) the second principal component for landscapes. However, portrait/still-life images did not show a significant correlation between similarity and preference, perhaps due to effects related to face perception. The preference data were then compared to a wide variety of image statistics relevant to early visual system coding. For landscapes and abstract works, nonlinear spatial and intensity statistics relevant to visual processing explained surprisingly large portions of the variance of preference. For abstract works, a quarter of the variance of preference rankings could be explained by a statistic gauging pixel sparseness. For landscape paintings, spatial frequency amplitude spectrum statistics explained one fifth of the variance of preference data. Consistent with results for similarity, image statistics for portrait/still-life works did not correlate significantly with preference. Finally, we addressed the role of value. If there are shared "rules" of preference, one might expect "free markets" to value art in proportion to its aesthetic appeal, at least to some extent. To assess the role of value, a further test of preference was performed on a separate set of paintings recently sold at auction. Results showed that the selling price of these works showed no correlation with preference, while basic statistics were significantly correlated with preference. We conclude that selling price, which could be seen as a proxy for a painting's "value," is not predictive of preference, while shared preferences may to some extent be predictable based on image statistics. We also suggest that contextual and semantic factors play an important role in preference given that image content appears to lead to greater divergence between similarity and preference ratings for representational works, and especially for artwork that prominently depicts faces. The present paper paves the way for a more complete understanding of the relationship between shared human preferences and image statistical regularities, and it outlines the basic geometry of perceptual spaces for artwork

Determination of the pion-nucleon coupling constant and scattering lengths

We critically evaluate the isovector GMO sum rule for forward pion-nucleon scattering using the recent precision measurements of negatively charged pion-proton and pion-deuteron scattering lengths from pionic atoms. We deduce the charged-pion-nucleon coupling constant, with careful attention to systematic and statistical uncertainties. This determination gives, directly from data a pseudoscalar coupling constant of 14.11+-0.05(statistical)+-0.19(systematic) or a pseudovector one of 0.0783(11). This value is intermediate between that of indirect methods and the direct determination from backward neutron-proton differential scattering cross sections. We also use the pionic atom data to deduce the coherent symmetric and antisymmetric sums of the negatively charged pion-proton and pion-neutron scattering lengths with high precision. The symmetric sum gives 0.0012+-0.0002(statistical)+-0.0008 (systematic) and the antisymmetric one 0.0895+-0.0003(statistical)+-0.0013(systematic), both in units of inverse charged pion-mass. For the need of the present analysis, we improve the theoretical description of the pion-deuteron scattering length.Comment: 27 pages, 5 figures, submitted to Phys. Rev. C, few modifications and clarifications, no change in substance of the pape

What is the crisis of Western sciences?

© 2016, Springer Science+Business Media Dordrecht. This article is an attempt to formulate a clear definition of the concept of crisis of Western sciences introduced by Husserl in his last work. The attempt will be based on a reading of the Krisis, which will stress its underlying continuity with Husserl’s life-long concerns about the theoretical insufficiency of positive sciences, and downplay the novelty of the idea of crisis itself within Husserl’s work. After insisting on the fact that, according to Husserl, only an account of the shortcomings of the scientificity of Western sciences can justify the claim that they are undergoing a crisis, it will be argued that the common definition of the crisis of the sciences as the loss of their significance for life rests on a misunderstanding. The crisis of Western sciences will be characterized, instead, as the repercussion of the crisis of the scientificity of philosophy (and, specifically, of metaphysics) on the scientificity of positive sciences. The loss of significance of scientific knowledge for our existence will in turn appear as a further, inevitable consequence of the uprooting of the sciences from the soil of a universal philosophy culminating in metaphysics, and thus, as a phenomenon deeply intertwined with the crisis of Western sciences, but not identical to it

Old wine in new bottles: Exploring pragmatism as a philosophical framework for the discipline of coaching

The practice and industry of organizational coaching are now well established, but how it is understood theoretically continues to lag behind. In this paper we analyze possible reasons for this state of affairs and argue that the development of coaching as an academic discipline will benefit from adopting philosophical pragmatism as an overarching theoretical framework. This move will enable coaching academics to utilize the contributions to knowledge that different paradigms generate. Positioning pragmatism as a theory of action we argue that organizational coaching is by default a pragmatic enterprise and provide three examples of the considerable benefits to be gained by conceptualizing it this way. (1) Drawing from the pragmatists’ ideas, particularly those of John Dewey, we demonstrate how the theoretical understanding of organizational coaching can be enhanced by considering its nature as a joint inquiry. (2) Pragmatism suggests development as an ultimate purpose for organizational coaching which also helps to resolve fundamental conceptual debates. (3) In light of the complexity and diversity involved in the way that organizational coaching is practiced, pragmatism offers coaches a useful framework for developing the flexibility required for navigating the multiplicity of influences on their practice

Level Spacings For SL(2,p)

We investigate the eigenvalue spacing distributions for randomly generated 4-regular Cayley graphs on SL 2 (Fp ) by numerically calculating their spectra. We present strong evidence that the distributions are Poisson and hence do not follow the Gaussian orthogonal ensemble. Among the Cayley graphs of SL 2 (Fp ) we consider are the new expander graphs recently discovered by Y. Shalom. In addition, we use a Markov chain method to generate random 4-regular graphs, and observe that the average eigenvalue spacings are closely approximated by the Wigner surmise