Binary Linear Classification and Feature Selection via Generalized Approximate Message Passing

For the problem of binary linear classification and feature selection, we propose algorithmic approaches to classifier design based on the generalized approximate message passing (GAMP) algorithm, recently proposed in the context of compressive sensing. We are particularly motivated by problems where the number of features greatly exceeds the number of training examples, but where only a few features suffice for accurate classification. We show that sum-product GAMP can be used to (approximately) minimize the classification error rate and max-sum GAMP can be used to minimize a wide variety of regularized loss functions. Furthermore, we describe an expectation-maximization (EM)-based scheme to learn the associated model parameters online, as an alternative to cross-validation, and we show that GAMP's state-evolution framework can be used to accurately predict the misclassification rate. Finally, we present a detailed numerical study to confirm the accuracy, speed, and flexibility afforded by our GAMP-based approaches to binary linear classification and feature selection

A Comparison of Three Curve Intersection Algorithms

An empirical comparison is made between three algorithms for computing the points of intersection of two planar Bezier curves. The algorithms compared are: the well known Bezier subdivision algorithm, which is discussed in Lane 80; a subdivision algorithm based on interval analysis due to Koparkar and Mudur; and an algorithm due to Sederberg, Anderson and Goldman which reduces the problem to one of finding the roots of a univariate polynomial. The details of these three algorithms are presented in their respective references

Germany as shipwreck: The “Robinson” trope in German diaries, 1943–1946

Drawing on unpublished diaries from the period 1943–46, this article shows how the “Robinson” trope of shipwreck and survival provided German civilians with a language to describe the transition from National Socialism to a radically open and anxiety-producing future. The identification with Robinson and his story makes the writers into agentic protagonists, at the same time that the metaphor of the “island” reflects an ambiguous position of isolation. Excerpts from diaries show how the “Robinson” trope combines dichotomies crucial to this period of turmoil: civilization and the primitive, individual and society, victimhood and agency, and how diarists rework this language to explore their place in a changing world.Drawing on unpublished diaries from the period 1943–46, this article shows how the “Robinson” trope of shipwreck and survival provided German civilians with a language to describe the transition from National Socialism to a radically open and anxiety-producing future. The identification with Robinson and his story makes the writers into agentic protagonists, at the same time that the metaphor of the “island” reflects an ambiguous position of isolation. Excerpts from diaries show how the “Robinson” trope combines dichotomies crucial to this period of turmoil: civilization and the primitive, individual and society, victimhood and agency, and how diarists rework this language to explore their place in a changing world

Curves with rational chord-length parametrization

It has been recently proved that rational quadratic circles in standard Bezier form are parameterized by chord-length. If we consider that standard circles coincide with the isoparametric curves in a system of bipolar coordinates, this property comes as a straightforward consequence. General curves with chord-length parametrization are simply the analogue in bipolar coordinates of nonparametric curves. This interpretation furnishes a compact explicit expression for all planar curves with rational chord-length parametrization. In addition to straight lines and circles in standard form, they include remarkable curves, such as the equilateral hyperbola, Lemniscate of Bernoulli and Limacon of Pascal. The extension to 3D rational curves is also tackled

Learning to make external sensory stimulus predictions using internal correlations in populations of neurons

To compensate for sensory processing delays, the visual system must make predictions to ensure timely and appropriate behaviors. Recent work has found predictive information about the stimulus in neural populations early in vision processing, starting in the retina. However, to utilize this information, cells downstream must in turn be able to read out the predictive information from the spiking activity of retinal ganglion cells. Here we investigate whether a downstream cell could learn efficient encoding of predictive information in its inputs in the absence of other instructive signals, from the correlations in the inputs themselves. We simulate learning driven by spiking activity recorded in salamander retina. We model a downstream cell as a binary neuron receiving a small group of weighted inputs and quantify the predictive information between activity in the binary neuron and future input. Input weights change according to spike timing-dependent learning rules during a training period. We characterize the readouts learned under spike timing-dependent learning rules, finding that although the fixed points of learning dynamics are not associated with absolute optimal readouts, they convey nearly all the information conveyed by the optimal readout. Moreover, we find that learned perceptrons transmit position and velocity information of a moving bar stimulus nearly as efficiently as optimal perceptrons. We conclude that predictive information is, in principle, readable from the perspective of downstream neurons in the absence of other inputs, and consequently suggests that bottom-up prediction may play an important role in sensory processing.Comment: 36 pages, 5 figures, 3 supplemental figure

Формування маркетингових підрозділів на підприємствах Харківського регіону

У статті розглянуто ситуацію формування маркетингових підрозділів на підприємствах Харківського регіону, розвиток їх структури, проаналізовано підходи до формування кадрового складу маркетингових підрозділів та динаміку їх розвитку, визначені тенденції щодо подальших напрямків вдосконалення маркетингу та виявлені ніші для перспективного розвитку маркетингу у Харківському регіоні.The article deals with the situation forming marketing departments in enterprises of Kharkov region, the development of structure analysis approaches to staffing marketing departments and the dynamics of their development trends identified areas for further improvement of marketing and found a niche for the future of marketing in the Kharkiv region

Computing Hypercircles by Moving Hyperplanes

Let K be a field of characteristic zero, alpha algebraic of degree n over K. Given a proper parametrization psi of a rational curve C, we present a new algorithm to compute the hypercircle associated to the parametrization psi. As a consequence, we can decide if the curve C is defined over K and, if not, to compute the minimum field of definition of C containing K. The algorithm exploits the conjugate curves of C but avoids computation in the normal closure of K(alpha) over K.Comment: 16 page