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A note on the Poincaré inequality

Alireza Ranjbar-Motlagh (2003)

Studia Mathematica

The Poincaré inequality is extended to uniformly doubling metric-measure spaces which satisfy a version of the triangle comparison property. The proof is based on a generalization of the change of variables formula.

A pointwise estimate for the solution to a linear Volterra integral equation

Angelo Morro (1983)

Atti della Accademia Nazionale dei Lincei. Classe di Scienze Fisiche, Matematiche e Naturali. Rendiconti Lincei. Matematica e Applicazioni

Utilizzando una generalizzazione della disuguaglianza di Gronwall si fornisce una stima puntuale per la soluzione dell’equazione lineare integrale di Volterra di seconda specie. Tale stima può essere applicata utilmente anche nello studio della stabilità di equazioni di evoluzione per mezzi continui.

A review of selected topics in majorization theory

Marek Niezgoda (2013)

Banach Center Publications

In this expository paper, some recent developments in majorization theory are reviewed. Selected topics on group majorizations, group-induced cone orderings, Eaton triples, normal decomposition systems and similarly separable vectors are discussed. Special attention is devoted to majorization inequalities. A unified approach is presented for proving majorization relations for eigenvalues and singular values of matrices. Some methods based on the Chebyshev functional and similarly separable vectors...

A sharp rearrangement inequality for the fractional maximal operator

A. Cianchi, R. Kerman, B. Opic, L. Pick (2000)

Studia Mathematica

We prove a sharp pointwise estimate of the nonincreasing rearrangement of the fractional maximal function of ⨍, M γ , by an expression involving the nonincreasing rearrangement of ⨍. This estimate is used to obtain necessary and sufficient conditions for the boundedness of M γ between classical Lorentz spaces.

A sharp weighted Wirtinger inequality

Tonia Ricciardi (2005)

Bollettino dell'Unione Matematica Italiana

We obtain a sharp estimate for the best constant C > 0 in the Wirtinger type inequality 0 2 π γ p ω 2 C 0 2 π γ q ω 2 where γ is bounded above and below away from zero, w is 2 π -periodic and such that 0 2 π γ p ω = 0 , and p + q 0 . Our result generalizes an inequality of Piccinini and Spagnolo.

A two-weight inequality for the Bessel potential operator

Yves Rakotondratsimba (1997)

Commentationes Mathematicae Universitatis Carolinae

Necessary conditions and sufficient conditions are derived in order that Bessel potential operator J s , λ is bounded from the weighted Lebesgue spaces L v p = L p ( n , v ( x ) d x ) into L u q when 1 < p q < .

A unified approach to several inequalities involving functions and derivatives

Javier Duoandikoetxea (2001)

Czechoslovak Mathematical Journal

There are many inequalities measuring the deviation of the average of a function over an interval from a linear combination of values of the function and some of its derivatives. A general setting is given from which the desired inequalities are obtained using Hölder’s inequality. Moreover, sharpness of the constants is usually easy to prove by studying the equality cases of Hölder’s inequality. Comparison of averages, extension to weighted integrals and n -dimensional results are also given.

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