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Invariant approximation for fuzzy nonexpansive mappings

Ismat Beg, Mujahid Abbas (2011)

Mathematica Bohemica

We establish results on invariant approximation for fuzzy nonexpansive mappings defined on fuzzy metric spaces. As an application a result on the best approximation as a fixed point in a fuzzy normed space is obtained. We also define the strictly convex fuzzy normed space and obtain a necessary condition for the set of all t -best approximations to contain a fixed point of arbitrary mappings. A result regarding the existence of an invariant point for a pair of commuting mappings on a fuzzy metric...

Irrationalité de valeurs de zêta

Stéphane Fischler (2002/2003)

Séminaire Bourbaki

Les valeurs aux entiers pairs (strictement positifs) de la fonction ζ de Riemann sont transcendantes, car ce sont des multiples rationnels de puissances de π . En revanche, on sait très peu de choses sur la nature arithmétique des ζ ( 2 k + 1 ) , pour k ≥ 1 entier. Apéry a démontré en 1978 que ζ ( 3 ) est irrationnel. Rivoal a prouvé en 2000 qu’une infinité de ζ ( 2 k + 1 ) sont irrationnels, mais sans pouvoir en exhiber aucun autre que ζ ( 3 ) . Il existe plusieurs points de vue sur la preuve d’Apéry ; celui des séries hypergéométriques...

Iterates of a class of discrete linear operators via contraction principle

Octavian Agratini, Ioan A. Rus (2003)

Commentationes Mathematicae Universitatis Carolinae

In this paper we are concerned with a general class of positive linear operators of discrete type. Based on the results of the weakly Picard operators theory our aim is to study the convergence of the iterates of the defined operators and some approximation properties of our class as well. Some special cases in connection with binomial type operators are also revealed.

Józef Marcinkiewicz (1910-1940) - on the centenary of his birth

Lech Maligranda (2011)

Banach Center Publications

Józef Marcinkiewicz’s (1910-1940) name is not known by many people, except maybe a small group of mathematicians, although his influence on the analysis and probability theory of the twentieth century was enormous. This survey of his life and work is in honour of the 100 t h anniversary of his birth and 70 t h anniversary of his death. The discussion is divided into two periods of Marcinkiewicz’s life. First, 1910-1933, that is, from his birth to his graduation from the University of Stefan Batory in Vilnius,...

Kaczmarz algorithm in Hilbert space

Rainis Haller, Ryszard Szwarc (2005)

Studia Mathematica

The aim of the Kaczmarz algorithm is to reconstruct an element in a Hilbert space from data given by inner products of this element with a given sequence of vectors. The main result characterizes sequences of vectors leading to reconstruction of any element in the space. This generalizes some results of Kwapień and Mycielski.

Kaczmarz algorithm with relaxation in Hilbert space

Ryszard Szwarc, Grzegorz Świderski (2013)

Studia Mathematica

We study the relaxed Kaczmarz algorithm in Hilbert space. The connection with the non-relaxed algorithm is examined. In particular we give sufficient conditions when relaxation leads to the convergence of the algorithm independently of the relaxation coefficients.

King type modification of q -Bernstein-Schurer operators

Mei-Ying Ren, Xiao-Ming Zeng (2013)

Czechoslovak Mathematical Journal

Very recently the q -Bernstein-Schurer operators which reproduce only constant function were introduced and studied by C. V. Muraru (2011). Inspired by J. P. King, Positive linear operators which preserve x 2 (2003), in this paper we modify q -Bernstein-Schurer operators to King type modification of q -Bernstein-Schurer operators, so that these operators reproduce constant as well as quadratic test functions x 2 and study the approximation properties of these operators. We establish a convergence theorem...

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