Zobrazeno 1 - 10 of 57 pro vyhledávání: '"Hubert Berens"'
1
Über ein Turánsches Problem für ℓ-1 radiale, positiv definite Funktionen
Autor: Elena E. Berdysheva, Hubert Berens
Publikováno v: Results in Mathematics. 47:17-32
Turan’s problem is to determine the greatest possible value of the integral ∫ℝ df(x)dx/ f (0) for positive definite functions f (x), x ∈ ℝd, supported in a given convex centrally symmetric body D ⊂ ℝd. In this note we consider the 2-dim
Externí odkaz: https://explore.openaire.eu/search/publication?articleId=doi_________::7866a9f72933677e3e0467adf1ad967f
https://doi.org/10.1007/bf03323009
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2
Elektronická kniha
Semi-Groups of Operators and Approximation
Autor: Paul Leo Butzer, Hubert Berens
In recent years important progress has been made in the study of semi-groups of operators from the viewpoint of approximation theory. These advances have primarily been achieved by introducing the theory of intermediate spaces. The applications of th
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4
On a Discrete Turán Problem for ℓ-1 Radial Functions
Autor: Elena E. Berdysheva, Hubert Berens
Publikováno v: New Perspectives on Approximation and Sampling Theory ISBN: 9783319088006
Turan’s problem for l-1 radial, positive definite functions is to determine the maximal possible value of the integral \(\int_{\mathbb{R}^{d}}f(\mathbf{x})\,d\mathbf{x}\) over the class of continuous, positive definite, l-1 radial functions \(f\) o
Externí odkaz: https://explore.openaire.eu/search/publication?articleId=doi_________::6523dec675a637bb0cb6330e408e3000
https://doi.org/10.1007/978-3-319-08801-3_19
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5
On l-1 riesz summability of the inverse Fourier integral
Autor: Yuan Xu, Zhongkai Li, Hubert Berens
Publikováno v: Indagationes Mathematicae. 12:41-53
On L( d), d ϵ , the l-1 Riesz (R, δ) means of the inverse Fourier transform converge almost everywhere provided δ > 0. The proof uses a new representation of the l-1 Riesz kernel derived from the l-1 Poisson kernel.
Externí odkaz: https://explore.openaire.eu/search/publication?articleId=doi_dedup___::91937ba7a6dee0d262279313ccf01c57
https://doi.org/10.1016/s0019-3577(01)80004-5
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6
Examples of Chebyshev Sets in Matrix Spaces
Autor: Alexey Rostislavovich Alimov, Hubert Berens
Publikováno v: Journal of Approximation Theory. 99:44-53
Let A be a matrix in Cn×n and let UΣV* be its singular value decomposition. The authors prove that for each 1⩽k⩽n the set S(k)1={S∈Cn×n:∑1⩽j1
Externí odkaz: https://explore.openaire.eu/search/publication?articleId=doi_dedup___::6f068c97357c55b57f11c7d235a9f25f
https://doi.org/10.1006/jath.1998.3311
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7
l-1 summability of multiple Fourier integrals and positivity
Autor: Hubert Berens, Yuan Xu
Publikováno v: Mathematical Proceedings of the Cambridge Philosophical Society. 122:149-172
Let f∈L1(ℝd), and let fˆ be its Fourier integral. We study summability of the l-1 partial integral S(1)R, d(f; x)= ∫[mid ]v[mid ][les ]Reiv·xfˆ(v)dv, x∈ℝd; note that the integral ranges over the l1-ball in ℝd centred at the origin with
Externí odkaz: https://explore.openaire.eu/search/publication?articleId=doi_________::f2321e20406c9398067fc337aa66de0f
https://doi.org/10.1017/s0305004196001521
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10
A Problem in Linear Matrix Approximation
Autor: M. Finzel, Hubert Berens
Publikováno v: Mathematische Nachrichten. 175:33-46
Let A be a normal operator in ℬ(H), H a complex Hilbert space, and let ℛ A = ≷ {AX - XA:X ∈ ℬ(H)} be the commutator subspace of ℬ(H) associated with A. If B in ℬ(H) commutes with A, then B is orthogonal to ℛA with respect to the spect
Externí odkaz: https://explore.openaire.eu/search/publication?articleId=doi_________::b5f290d092dd91982961d64eb3ce25e7
https://doi.org/10.1002/mana.19951750104
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