scholarly journals A link between Lebesgue constants and Hermite-Fejér interpolation

1986 ◽  
Vol 33 (2) ◽  
pp. 207-218 ◽  
Author(s):  
S. J. Goodenough

A review of the development of estimates for Lebesgue constants associated with Lagrange interpolation on the one hand, and estimates for the rate of convergence of Hermite-Fejér interpolation on the other hand, provides a historical perspective for the following surprising, close link between these apparently diverse concepts. Denoting by Λn (T) the Lebesgue constant of order n and by Δn (T) the maximum interpolation error for functions of class Lip 1 by Hexmite-Fejér interpolation polynomials of degree not exceeding 2n − 1, based on the zeros of the Chebyshev polynomial of first kind, we discover that, for even values of n, Λn(T) = n Δn(T).

Author(s):  
Marlou Schrover

This chapter discusses social exclusion in European migration from a gendered and historical perspective. It discusses how from this perspective the idea of a crisis in migration was repeatedly constructed. Gender is used in this chapter in a dual way: attention is paid to differences between men and women in (refugee) migration, and to differences between men and women as advocates and claim makers for migrant rights. There is a dilemma—recognized mostly for recent decades—that on the one hand refugee women can be used to generate empathy, and thus support. On the other hand, emphasis on women as victims forces them into a victimhood role and leaves them without agency. This dilemma played itself out throughout the twentieth century. It led to saving the victims, but not to solving the problem. It fortified rather than weakened the idea of a crisis.


Author(s):  
B. Choudhary

Integral transformations analogous to the Nörlund means have been introduced and investigated by Kuttner, Knopp and Vanderburg(6), (5), (4). It is known that with any regular Nörlund mean (N, p) there is associated a functionregular for |z| < 1, and if we have two Nörlund means (N, p) and (N, r), where (N, pr is regular, while the function is regular for |z| ≤ 1 and different) from zero at z = 1, then q(z) = r(z)p(z) belongs to a regular Nörlund mean (N, q). Concerning Nörlund means Peyerimhoff(7) and Miesner (3) have recently obtained the relation between the convergence fields of the Nörlund means (N, p) and (N, r) on the one hand and the convergence field of the Nörlund mean (N, q) on the other hand.


2000 ◽  
Vol 62 (3) ◽  
pp. 357-368 ◽  
Author(s):  
Michael Revers

A well-known result due to S.N. Bernstein is that sequence of Lagrange interpolation polynomials for |x| at equally spaced nodes in [−1, 1] diverges everywhere, except at zero and the end-points. In this paper we present a quantitative version concerning the divergence behaviour of the Lagrange interpolants for |x|3 at equidistant nodes. Furthermore, we present the exact rate of convergence for the interpolatory parabolas at the point zero.


1929 ◽  
Vol 25 (2) ◽  
pp. 219-221
Author(s):  
T. M. Lowry

Two alternative views have been expressed in regard to the configuration of quadrivalent atoms. On the one hand le Bel and van't Hoff assigned to quadrivalent carbon a tetrahedral configuration, which has since been confirmed by the X-ray analysis of the diamond. On the other hand, Werner in 1893 adopted an octahedral configuration for radicals of the type MA6, e.g. inand then suggested that “the molecules [MA4]X2 are incomplete molecules [MA6]X2. The radicals [MA4] result from the octahedrally-conceived radicals [MA6] by loss of two groups A, but with no function-change of the acid residue…. They behave as if the bivalent metallic atom in the centre of the octahedron could no longer bind all six of the groups A and lost two of them leaving behind the fragment [MA4]” (p. 303).


2019 ◽  
Vol 19 (5-6) ◽  
pp. 705-721
Author(s):  
GIOVANNI AMENDOLA ◽  
FRANCESCO RICCA ◽  
MIROSLAW TRUSZCZYNSKI

AbstractAnswer Set Programming (ASP) is a logic programming paradigm featuring a purely declarative language with comparatively high modeling capabilities. Indeed, ASP can model problems in NP in a compact and elegant way. However, modeling problems beyond NP with ASP is known to be complicated, on the one hand, and limited to problems in $\[\Sigma _2^P\]$ on the other. Inspired by the way Quantified Boolean Formulas extend SAT formulas to model problems beyond NP, we propose an extension of ASP that introduces quantifiers over stable models of programs. We name the new language ASP with Quantifiers (ASP(Q)). In the paper we identify computational properties of ASP(Q); we highlight its modeling capabilities by reporting natural encodings of several complex problems with applications in artificial intelligence and number theory; and we compare ASP(Q) with related languages. Arguably, ASP(Q) allows one to model problems in the Polynomial Hierarchy in a direct way, providing an elegant expansion of ASP beyond the class NP.


2009 ◽  
Vol 22 (1) ◽  
pp. 1-28 ◽  
Author(s):  
ANNE-CHARLOTTE MARTINEAU

AbstractOver the last decade international lawyers have been increasingly concerned with the ‘fragmentation’ of international law. However, given that this expression has been repeatedly used by the profession since the mid-nineteenth century to depict the state of international law, one may wonder about its recent revival in the international legal discourse. Why has it re-emerged? What can we learn from previous invocations? An answer may be sought by contextualizing the fragmentation debate in a historical perspective. This brings out the repetitive and relatively stylized modes in which the profession has narrated legal developments. This essay suggests a correlation between periods of crisis in general and a critical view of fragmentation on the one hand, and periods of scholarly enthusiasm and the prevalence of positive views about fragmentation on the other. This analysis sheds critical light on both the implicit assumptions and political implications of the current debate on fragmentation.


1987 ◽  
Vol 21 (4) ◽  
pp. 667-678
Author(s):  
Ian Nish

As Britain saw it, trade was not the prime motivating force for Russian expansion in east Asia or, put another way, the Russian frontiersmen were not driven by the actual amount of their trade there or its future potentialities. While Russia was primarily concerned with the tea trade over land frontiers, Britain was concerned with the seaborne commerce of China. The customs revenue paid to China in the year 1894 worked out as follows:Judging from the returns of the Chinese Imperial Maritime Customs Organization, British ships carried 83.5% of China's total trade. But Britain's commercial dominance affected her political stance because she wanted to preserve China's stability for most of the second half of the nineteenth century. This was at the root of the political tensions between Britain and Russia which emerged in China after 1860 and especially those which derived from the spate of railway building which took place from 1890 onwards. It would be foolish to deny that intense rivalry did exist in the area from time to time or that detailed observations of the actions of the one were regularly conducted by the other—what we should now call ‘intelligence operations’. But what I shall suggest in this paper is that, despite all the admitted antagonism and suspicion between Britain and Russia in east Asia, Britain regularly made efforts to reach accommodations with Russia in north-east Asia.


1882 ◽  
Vol 23 (5) ◽  
pp. 335-352 ◽  
Author(s):  
John Adams Higham

Mr. John Finlaison's method of graduation (Journal, vol. xxi, page 50) deals with an irregularity, which, for convenience, may be assumed to be unity, in the following manner:—It diminishes the irregularity to a small fraction on its first appearance at one end of the formula; conducts it along the formula by easy stages, as over a double inclined plane; and dismisses it gently at the other end. The method has the advantage of simplicity in working and check, but it is correct to first differences only.Mr. Woolhouse's method is correct to third differences, and the irregularity glides over a curve; but the application of the formula requires sustained attention.The object of this paper is to combine the facility of the one method with the smoothness and correctness of the other.Let S be the sum of nine numbers, u0 to u8, increasing by third differences,the central term, whence .


2016 ◽  
Vol 8 (4) ◽  
pp. 118 ◽  
Author(s):  
Maha Youssef ◽  
Hany A. El-Sharkawy ◽  
Gerd Baumann

This paper gives an explicit construction of multivariate Lagrange interpolation at Sinc points. A nested operator formula for Lagrange interpolation over an $m$-dimensional region is introduced. For the nested Lagrange interpolation, a proof of the upper bound of the error is given showing that the error has an exponentially decaying behavior. For the uniform convergence the growth of the associated norms of the interpolation operator, i.e., the Lebesgue constant has to be taken into consideration. It turns out that this growth is of logarithmic nature $O((log n)^m)$. We compare the obtained Lebesgue constant bound with other well known bounds for Lebesgue constants using different set of points.


1951 ◽  
Vol 16 (1) ◽  
pp. 43-45
Author(s):  
Maurice L'abbé

A general system of axioms has been given by Henkin for a fragment of the propositional calculus having as primitive symbols, in addition to the usual parentheses, variables, and implication sign ⊃, an arbitrarily given truth function symbol ϕ. This system of axioms, which we shall denote by S(⊃, ϕ), contains the following three axiom schemataplus the 2m further axiom schemata involving the symbol ϕwhere ϕ is an m-placed function symbol. We refer to Henkin's paper, p. 43, for the detailed description of the axiom schemata (4).The remark was made in the above mentioned paper that each of the 2m axiom schemata of (4) is trivially independent of the rest of the axioms of S(⊃, ϕ), and it was conjectured that the axiom schemata (1), (2) and (3) are also independent. In this note, we prove the general independence of the axiom schemata (1) and (2). As for (3), we show on the one hand its independence in the systems S(⊃) and S(⊃, f), and, on the other hand, its dependence in the system S(⊃, ∼). The net result is, therefore, that in any of these systems of axioms S(⊃, ϕ) all the axiom schemata are independent, except possibly the axiom schema (3).


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