scholarly journals Embeddings of homogeneous Sobolev spaces on the entire space

2020 ◽  
pp. 1-33 ◽  
Author(s):  
Zdeněk Mihula
Keyword(s):  
Sobolev Spaces ◽  
Orlicz Spaces ◽  
Function Spaces ◽  
The Other ◽  
Rearrangement Invariant Space ◽  
Entire Space ◽  
Invariant Space ◽  
One Dimensional ◽  
Homogeneous Sobolev Spaces ◽  
Invariant Spaces

Abstract We completely characterize the validity of the inequality $\| u \|_{Y(\mathbb R)} \leq C \| \nabla^{m} u \|_{X(\mathbb R)}$ , where X and Y are rearrangement-invariant spaces, by reducing it to a considerably simpler one-dimensional inequality. Furthermore, we fully describe the optimal rearrangement-invariant space on either side of the inequality when the space on the other side is fixed. We also solve the same problem within the environment in which the competing spaces are Orlicz spaces. A variety of examples involving customary function spaces suitable for applications is also provided.

Extrapolation of Lp Data from a Modular Inequality

2002 ◽  
Vol 45 (1) ◽  
pp. 25-35
Author(s):  
Steven Bloom ◽  
Ron Kerman
Keyword(s):  
Orlicz Spaces ◽  
Rearrangement Invariant Space ◽  
Invariant Space ◽  
Partial Converse

AbstractIf an operator T satisfies a modular inequality on a rearrangement invariant space Lρ(Ω, μ), and if p is strictly between the indices of the space, then the Lebesgue inequality holds. This extrapolation result is a partial converse to the usual interpolation results. A modular inequality for Orlicz spaces takes the form , and here, one can extrapolate to the (finite) indices i(Φ) and I(Φ) aswell.

scholarly journals Large semigroups of cellular automata

2011 ◽  
Vol 32 (6) ◽  
pp. 1991-2010 ◽  
Author(s):  
YAIR HARTMAN
Keyword(s):  
Cellular Automata ◽  
Field Structure ◽  
The Other ◽  
Entire Space ◽  
Dimensional Torus ◽  
Semigroup Action ◽  
Closed Set ◽  
One Dimensional ◽  
Shift Space ◽  
The One

AbstractIn this article, we consider semigroups of transformations of cellular automata which act on a fixed shift space. In particular, we are interested in two properties of these semigroups which relate to ‘largeness’: first, a semigroup has the ID (infinite is dense) property if the only infinite invariant closed set (with respect to the semigroup action) is the entire space; the second property is maximal commutativity (MC). We shall consider two examples of semigroups: one is spanned by cellular automata transformations that represent multiplications by integers on the one-dimensional torus, and the other one consists of all the cellular automata transformations which are linear (when the symbols set is the ring ℤ/sℤ). It will be shown that these two properties of these semigroups depend on the number of symbols s. The multiplication semigroup is ID and MC if and only if s is not a power of a prime. The linear semigroup over the mentioned ring is always MC but is ID if and only if s is prime. When the symbol set is endowed with a finite field structure (when possible), the linear semigroup is both ID and MC. In addition, we associate with each semigroup which acts on a one-sided shift space a semigroup acting on a two-sided shift space, and vice versa, in a way that preserves the ID and the MC properties.

scholarly journals Diffeomorphic approximation of Planar Sobolev Homeomorphisms in rearrangement invariant spaces

2021 ◽  
Author(s):  
Daniel Campbell ◽  
Luigi Greco ◽  
Roberta Schiattarella ◽  
Filip Soudsky
Keyword(s):  
Rearrangement Invariant Space ◽  
Invariant Space ◽  
Rearrangement Invariant Spaces ◽  
Invariant Spaces

Let $\Omega\subseteq\mathcal{R}^2$ be a domain, let $X$ be a rearrangement invariant space and let $f\in W^{1}X(\Omega,\mathcal{R}^2)$ be a homeomorphism between $\Omega$ and $f(\Omega)$. Then there exists a sequence of diffeomorphisms $f_k$ converging to $f$ in the space $W^{1}X(\Omega,\mathcal{R}^2)$.

scholarly journals K-ENVELOPES FOR REAL INTERPOLATION METHODS

2012 ◽  
Vol 55 (2) ◽  
pp. 293-307
Author(s):  
MING FAN
Keyword(s):  
Function Space ◽  
Upper Bounds ◽  
Function Spaces ◽  
Real Interpolation ◽  
Rearrangement Invariant Space ◽  
Interpolation Spaces ◽  
Invariant Space ◽  
Bounded Operators ◽  
Fundamental Function ◽  
Interpolation Methods

AbstractIn this paper, we study the K-envelopes of the real interpolation methods with function space parameters in the sense of Brudnyi and Kruglyak [Y. A. Brudnyi and N. Ja. Kruglyak, Interpolation functors and interpolation spaces (North-Holland, Amsterdam, Netherlands, 1991)]. We estimate the upper bounds of the K-envelopes and the interpolation norms of bounded operators for the KΦ-methods in terms of the fundamental function of the rearrangement invariant space related to the function space parameter Φ. The results concerning the quasi-power parameters and the growth/continuity envelopes in function spaces are obtained.

Indices of Function Spaces and their Relationship to Interpolation

1969 ◽  
Vol 21 ◽  
pp. 1245-1254 ◽  
Author(s):  
David W. Boyd
Keyword(s):  
Linear Operator ◽  
Function Space ◽  
Weak Type ◽  
General Theorem ◽  
Function Spaces ◽  
Rearrangement Invariant Space ◽  
Invariant Space ◽  
Special Case

A special case of the theorem of Marcinkiewicz states that if T is a linear operator which satisfies the weak-type conditions (p, p) and (q,q), then T maps Lr continuously into itself for any r with p < r < q. In a recent paper (5), as part of a more general theorem, Calderόn has characterized the spaces X which can replace Lr in the conclusion of this theorem, independent of the operator T. The conditions which X must satisfy are phrased in terms of an operator S(σ) which acts on the rearrangements of the functions in X.One of Calderόn's results implies that if X is a function space in the sense of Luxemburg (9), then X must be a rearrangement-invariant space.

scholarly journals A note on function spaces generated by Rademacher series

1997 ◽  
Vol 40 (1) ◽  
pp. 119-126 ◽  
Author(s):  
Guillermo P. Curbera
Keyword(s):  
Function Space ◽  
Invariant Function ◽  
Function Spaces ◽  
Lorentz Spaces ◽  
Rearrangement Invariant Space ◽  
Invariant Space ◽  
Fundamental Function ◽  
Rademacher Functions ◽  
Measurable Functions ◽  
Rademacher Series

Let X be a rearrangement invariant function space on [0,1] in which the Rademacher functions (rn) generate a subspace isomorphic to ℓ2. We consider the space Λ(R, X) of measurable functions f such that fg∈X for every function g=∑bnrn where (bn)∈ℓ2. We show that if X satisfies certain conditions on the fundamental function and on certain interpolation indices then the space Λ(R, X) is not order isomorphic to a rearrangement invariant space. The result includes the spaces Lp, q and certain classes of Orlicz and Lorentz spaces. We also study the cases X = Lexp and X = Lψ2 for ψ2) = exp(t2) – 1.

scholarly journals The strong Fatou property of risk measures

2018 ◽  
Vol 6 (1) ◽  
pp. 183-196 ◽  
Author(s):  
Shengzhong Chen ◽  
Niushan Gao ◽  
Foivos Xanthos
Keyword(s):  
Risk Measures ◽  
Lower Semicontinuous ◽  
Rearrangement Invariant Space ◽  
Invariant Space ◽  
Fatou Property ◽  
Rearrangement Invariant Spaces ◽  
Dual Representations ◽  
Wide Range ◽  
Invariant Functional ◽  
Invariant Spaces

AbstractIn this paper, we explore several Fatou-type properties of risk measures. The paper continues to reveal that the strong Fatou property,whichwas introduced in [19], seems to be most suitable to ensure nice dual representations of risk measures. Our main result asserts that every quasiconvex law-invariant functional on a rearrangement invariant space X with the strong Fatou property is (X, L1) lower semicontinuous and that the converse is true on a wide range of rearrangement invariant spaces. We also study inf-convolutions of law-invariant or surplus-invariant risk measures that preserve the (strong) Fatou property.

scholarly journals New classes of rearrangement-invariant spaces appearing in extreme cases of weak interpolation

2006 ◽  
Vol 4 (3) ◽  
pp. 275-304 ◽  
Author(s):  
Evgeniy Pustylnik ◽  
Teresa Signes
Keyword(s):  
Weak Type ◽  
Interpolation Theorem ◽  
Optimal Interpolation ◽  
Rearrangement Invariant Space ◽  
Invariant Space ◽  
Type Interpolation ◽  
Rearrangement Invariant Spaces ◽  
Invariant Spaces ◽  
Quasiconcave Function

We study weak type interpolation for ultrasymmetric spacesL?,Ei.e., having the norm??(t)f*(t)?E˜, where?(t)is any quasiconcave function andE˜is arbitrary rearrangement-invariant space with respect to the measuredt/t. When spacesL?,Eare not “too close” to the endpoint spaces of interpolation (in the sense of Boyd), the optimal interpolation theorem was stated in [13]. The case of “too close” spaces was studied in [15] with results which are optimal, but only among ultrasymmetric spaces. In this paper we find better interpolation results, involving new types of rearrangement-invariant spaces,A?,b,EandB?,b,E, which are described and investigated in detail.

Regions-based Two-dimensional Continua: The Euclidean Case

2018 ◽  
Author(s):  
Geoffrey Hellman ◽  
Stewart Shapiro
Keyword(s):  
Mathematical Induction ◽  
Dimensional Case ◽  
Two Dimensional ◽  
Entire Space ◽  
Euclidean Case ◽  
Free Basis ◽  
One Dimensional ◽  
Archimedean Property ◽  
The One

This chapter develops a Euclidean, two-dimensional, regions-based theory. As with the semi-Aristotelian account in Chapter 2, the goal here is to recover the now orthodox Dedekind–Cantor continuum on a point-free basis. The chapter derives the Archimedean property for a class of readily postulated orientations of certain special regions, what are called “generalized quadrilaterals” (intended as parallelograms), by which the entire space is covered. Then the chapter generalizes this to arbitrary orientations, and then establishes an isomorphism between the space and the usual point-based one. As in the one-dimensional case, this is done on the basis of axioms which contain no explicit “extremal clause”, and we have no axiom of induction other than ordinary numerical (mathematical) induction.

scholarly journals Viscous Flow Around a Rigid Body Performing a Time-periodic Motion

2021 ◽  
Vol 23 (1) ◽  
Author(s):  
Thomas Eiter ◽  
Mads Kyed
Keyword(s):  
Rigid Body ◽  
Sobolev Spaces ◽  
Periodic Motion ◽  
Viscous Incompressible Fluid ◽  
Body Motion ◽  
Translational Velocity ◽  
Ill Posed ◽  
Homogeneous Sobolev Spaces ◽  
The Mean ◽  
Time Periodic

AbstractThe equations governing the flow of a viscous incompressible fluid around a rigid body that performs a prescribed time-periodic motion with constant axes of translation and rotation are investigated. Under the assumption that the period and the angular velocity of the prescribed rigid-body motion are compatible, and that the mean translational velocity is non-zero, existence of a time-periodic solution is established. The proof is based on an appropriate linearization, which is examined within a setting of absolutely convergent Fourier series. Since the corresponding resolvent problem is ill-posed in classical Sobolev spaces, a linear theory is developed in a framework of homogeneous Sobolev spaces.

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