The classical Gagliardo-Nirenberg interpolation inequality is a well-known estimate which gives, in particular, an estimate for the Lebesgue norm of intermediate derivatives of functions in Sobolev spaces. We present ...
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The classical Gagliardo-Nirenberg interpolation inequality is a well-known estimate which gives, in particular, an estimate for the Lebesgue norm of intermediate derivatives of functions in Sobolev spaces. We present an extension of this estimate into the scale of the general rearrangement-invariant banach function spaces with the proof based on the Maz'ya's pointwise estimates. As corollaries, we present the Gagliardo-Nirenberg inequality for intermediate derivatives in the case of triples of Orlicz spaces and triples of Lorentz spaces. Finally, we promote the scaling argument to validate the optimality of the Gagliardo-Nirenberg inequality and show that the presented estimate in Orlicz scale is optimal.
This paper deals with bilinear operators acting in pairs of banach function spaces that factor through the pointwise product. We find similar situations in different contexts of the functional analysis, including abst...
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This paper deals with bilinear operators acting in pairs of banach function spaces that factor through the pointwise product. We find similar situations in different contexts of the functional analysis, including abstract vector lattices-orthosymmetric maps, C-algebras-zero product preserving operators, and classical and harmonic analysis-integral bilinear operators. Bringing together the ideas of these areas, we show new factorization theorems and characterizations by means of norm inequalities. The objective of the paper is to apply these tools to provide new descriptions of some classes of bilinear integral operators, and to obtain integral representations for abstract classes of bilinear maps satisfying certain domination properties.
In this paper, we give characterizations for a polynomial stability in banachspaces. This is done by using evolution cocycles and techniques of banach function spaces. Our characterizations are new versions of the th...
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In this paper, we give characterizations for a polynomial stability in banachspaces. This is done by using evolution cocycles and techniques of banach function spaces. Our characterizations are new versions of the theorems of Datko type.
作者:
Steyn, ClaudNWU
Sch Math & Stat Sci DST NRF CoE Math & Stat Sci Unit BMI Internal Box 209Pvt Bag X6001 ZA-2520 Potchefstroom South Africa
We use a weighted analogue of a trace to define a weighted non-commutative decreasing rearrangement and show its relationship with the singular value function. We further show an alternative approach to constructing w...
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We use a weighted analogue of a trace to define a weighted non-commutative decreasing rearrangement and show its relationship with the singular value function. We further show an alternative approach to constructing weighted non-commutative banach function spaces using weighted non-commutative decreasing rearrangements and prove that this approach is equivalent to the original approach by Labuschagne and Majewski.
We consider pairs of non reflexive banachspaces (E-0, E) such that E-0 is defined in terms of a little-o condition and E is defined by the corresponding big-O condition. Under suitable assumptions on the pair (E-0, E...
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We consider pairs of non reflexive banachspaces (E-0, E) such that E-0 is defined in terms of a little-o condition and E is defined by the corresponding big-O condition. Under suitable assumptions on the pair (E-0, E) there exists a reflexive and separable banach space X (in which E is continuously embedded and dense) naturally associated to E which characterizes quantitatively weak compactness of bounded linear operators T : E-0 -> Z where Z is an arbitrary banach space. Pairs include (VMO, BMO), where BMO is the space of John-Nirenberg, (B-0, B) where B is a recently introduced space by Bourgain-Brezis-Mironescu ([6]) and some Orlicz pairs (L-0(psi), L-psi) where L-0(psi) is the closure of L-infinity in the Orlicz space L-psi, Marcinkiewicz pairs (L-0(q,infinity), L-q,L-infinity) where L-0(q infinity), is the closure of L-infinity in the Marcinkiewicz weak-L-q denoted by L-q,L-infinity. More generally, banach function spaces are considered. The main results are duality formulas of the type E-0** similar or equal to E isometrically (1) E* similar or equal to E-0* circle plus(1) E-0(perpendicular to) (2) and distance formulas.
Let be a banachfunction space, E the Kothe dual of E and (X, center dot X) be a banach space. It is shown that every Bochner representable operator T : E -> X maps relatively sigma (E, E')-compact sets in E on...
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Let be a banachfunction space, E the Kothe dual of E and (X, center dot X) be a banach space. It is shown that every Bochner representable operator T : E -> X maps relatively sigma (E, E')-compact sets in E onto relatively norm compact sets in X. If, in particular, the associated norm on E is order continuous, then every Bochner representable operator T : E X is X compact, where E stands for the natural mixed topology on E. Applications to Bochner representable operators on Orlicz spaces are given.
作者:
de Beer, RichardLabuschagne, LouisNWU
DST NRF CoE Math & Stat Sci Unit BMI Sch Comp Stat & Math Sci Internal Box 209Pvt Bag X6001 ZA-2520 Potchefstroom South Africa
We analyse the Transfer Principle, which is used to generate weak type maximal inequalities for ergodic operators, and extend it to the general case of a-compact locally compact Hausdorff groups acting measure-preserv...
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We analyse the Transfer Principle, which is used to generate weak type maximal inequalities for ergodic operators, and extend it to the general case of a-compact locally compact Hausdorff groups acting measure-preservingly on sigma-finite measure spaces. We show how the techniques developed here generate various weak type maximal inequalities on different banach function spaces, and how the properties of these functionspaces influence the weak type inequalities that can be obtained. Next we demonstrate how the techniques developed imply almost sure pointwise convergence of a wide class of ergodic averages. In closing we briefly indicate the utility of these results for Statistical Physics. (C) 2015 Royal Dutch Mathematical Society (KWG). Published by Elsevier B.V. All rights reserved.
Let s(n)(T) denote the nth approximation, isomorphism, Gelfand, Kolmogorov or Bernstein number of the Hardy-type integral operator T given by T f(x) = v(x) integral(x)(a) u(t) f(t)dt, x is an element of (a, b) (-infin...
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Let s(n)(T) denote the nth approximation, isomorphism, Gelfand, Kolmogorov or Bernstein number of the Hardy-type integral operator T given by T f(x) = v(x) integral(x)(a) u(t) f(t)dt, x is an element of (a, b) (-infinity < a < b < +infinity) and mapping a banachfunction space E to itself. We investigate some geometrical properties of E for which C-1 integral(b)(a) u(x)v(x)dx <= lim(n ->infinity) inf ns(n) (T) <= lim(n ->infinity)sup ns(n)(T) <= C-2 integral(b)(a) u(x)v(x)dx under appropriate conditions on it and v. The constants C-1, C-2 > 0 depend only on the space E. (C) 2016 Elsevier Inc. All rights reserved.
We consider the problem of extending or factorizing a bounded bilinear map defined on a couple of order continuous banach function spaces to its optimal domain, i.e. the biggest couple of banach function spaces to whi...
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We consider the problem of extending or factorizing a bounded bilinear map defined on a couple of order continuous banach function spaces to its optimal domain, i.e. the biggest couple of banach function spaces to which the bilinear map can be extended. As in the case of linear operators, we use vector measure techniques to find this space, and we show that this procedure cannot be always successfully used for bilinear maps. We also present some applications to find optimal factorizations of linear operators between banach function spaces.
The well-known factorization theorem of Lozanovskii may be written in the form L-1 E circle dot E', where circle dot means the pointwise product of banach ideal spaces. A natural generalization of this problem wou...
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The well-known factorization theorem of Lozanovskii may be written in the form L-1 E circle dot E', where circle dot means the pointwise product of banach ideal spaces. A natural generalization of this problem would be the question when one can factorize F through E, i.e., when F E circle dot M(E, F), where M(E, F) is the space of pointwise multipliers from E to F. Properties of M(E, F) were investigated in our earlier paper [41] and here we collect and prove some properties of the construction E circle dot F. The formulas for pointwise product of Calderon-Lozanovskii E-phi-spaces, Lorentz spaces and Marcinkiewicz spaces are proved. These results are then used to prove factorization theorems for such spaces. Finally, it is proved in Theorem 11 that under some natural assumptions, a rearrangement invariant banachfunction space may be factorized through a Marcinkiewicz space. (C) 2013 Elsevier Inc. All rights reserved.
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