Search results for "Descent"

Some perturbation results through localized SVEP

2016

Some classical perturbation results on Fredholm theory are proved and extended by using the stability of the localized single-valued extension property under Riesz commuting perturbations. In the last part, we give some results concerning the stability of property (gR) and property (gb.

On a global superconvergence of the gradient of linear triangular elements

1987

Abstract We study a simple superconvergent scheme which recovers the gradient when solving a second-order elliptic problem in the plane by the usual linear elements. The recovered gradient globally approximates the true gradient even by one order of accuracy higher in the L 2 -norm than the piecewise constant gradient of the Ritz—Galerkin solution. A superconvergent approximation to the boundary flux is presented as well.

A new method for optimal synthesis of wavelet-based neural networks suitable for identification purposes

1999

Abstract This paper deals with a new method for optimal synthesis of Wavelet-Based Neural Networks (WBNN) suitable for identification purposes. The method uses a genetic algorithm (GA) combined with a steepest descent technique and least square techniques for both optimal selection of the structure of the WBNN and its training. The method is applied for designing a predictor for a chaotic temporal series

Estimation of Granger causality through Artificial Neural Networks: applications to physiological systems and chaotic electronic oscillators

2021

One of the most challenging problems in the study of complex dynamical systems is to find the statistical interdependencies among the system components. Granger causality (GC) represents one of the most employed approaches, based on modeling the system dynamics with a linear vector autoregressive (VAR) model and on evaluating the information flow between two processes in terms of prediction error variances. In its most advanced setting, GC analysis is performed through a state-space (SS) representation of the VAR model that allows to compute both conditional and unconditional forms of GC by solving only one regression problem. While this problem is typically solved through Ordinary Least Sq…

Gada as an Integrative Factor of Political Organization

1994

Sull'organizzazione sociale tradizionale dei Borana: Contributo al dibattito

1988

This article deals with the traditional social organization of the Borana, an Oromo-speaking pastoral group of Northern Kenya and Southern Ethiopia. A special attention is reserved to the political role of four basic institutions: the kinship system, the gadaa system, the hariyaa system and the qaalluu. Cet article concerne l'organisation sociale des Borana, un groupe pastoral de langue Oromo du Kenya septentrional et de l'Ethiopie méridionale. Une attention particulière est portée au rôle politique de quatre institutions fondamentales: le système de parenté, les systèmes gadaa et hariyaa, et le qaalluu.

Sviluppo partecipante e sistemi tradizionali: Il caso dei Borana dell'Etiopia

1992

In the development programs concerning the Ethiopian Borana local groups are assigned the role of principal group for development initiatives. As such, the project seems to meet the principle of participatory development. However, among the Borana, local communities have very little organizational significance and no say at all on matters regarding rights of property. Such authority is instead attributed to descent groups, which are not localized. In particular, clans have both the organizational capacity to coordinate collective investments on natural resources and the authority to guarantee personal and collective property rights. It is therefore suggested that a direct link with clans an…

Il caso Diigalu Tiiti. Strutture sociali e processi produttivi presso i Borana dell'Etiopia

1990

This paper concerns the social elements which are relevant in relation with some important productive features of the Borana of Southern Ethiopia. Recent field-data seem to indicate that the structure provided by descent is particularly significant with regard both to economical mutual assistance and to management of wells, the crucial natural resources. Cet article concerne les éléments sociaux importants par rapport à des procédés de production des Borana du sud de l'Ethiopie. Le système de parenté semble particulièrement significatif aussi bien en ce qui concerne l'assistance réciproque que pour la gestion des puits, la ressource naturelle cruciale.

On the methods of nonsmooth optimization

2005

In this paper we shall give a short derivation of the most promising methods in nonsmooth optimization, namely bundle methods. We introduce the basic bundle idea due to Lemarechal and several modifications by Kiwiel, Schramm and Zowe. To the end we shall give some numerical results comparing the efficience of these methods. As test problems we have used well-known test problems from litterature and in addition we shall give some contributions to nonsmooth optimal control problems.

Regularized Regression Incorporating Network Information: Simultaneous Estimation of Covariate Coefficients and Connection Signs

2014

We develop an algorithm that incorporates network information into regression settings. It simultaneously estimates the covariate coefficients and the signs of the network connections (i.e. whether the connections are of an activating or of a repressing type). For the coefficient estimation steps an additional penalty is set on top of the lasso penalty, similarly to Li and Li (2008). We develop a fast implementation for the new method based on coordinate descent. Furthermore, we show how the new methods can be applied to time-to-event data. The new method yields good results in simulation studies concerning sensitivity and specificity of non-zero covariate coefficients, estimation of networ…