Quasiconformal mappings and exponentially integrable functions

Fernando Farroni; Raffaella Giova

Displaying similar documents to “Quasiconformal mappings and exponentially integrable functions”

Isomorphic classification of the tensor products $E ₀ (e x p α i) \otimes ̂ E_{\infty} (e x p β j)$

Peter Chalov, Vyacheslav Zakharyuta (2011)

Studia Mathematica

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It is proved, using so-called multirectangular invariants, that the condition αβ = α̃β̃ is sufficient for the isomorphism of the spaces $E ₀ (e x p α i) \otimes ̂ E_{\infty} (e x p β j)$ and $E ₀ (e x p α ̃ i) \otimes ̂ E_{\infty} (e x p β ̃ j)$ . This solves a problem posed in [14, 15, 1]. Notice that the necessity has been proved earlier in [14].

Rings of PDE-preserving operators on nuclearly entire functions

Henrik Petersson (2004)

Studia Mathematica

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Let E,F be Banach spaces where F = E’ or vice versa. If F has the approximation property, then the space of nuclearly entire functions of bounded type, $ℋ_{N b} (E)$ , and the space of exponential type functions, Exp(F), form a dual pair. The set of convolution operators on $ℋ_{N b} (E)$ (i.e. the continuous operators that commute with all translations) is formed by the transposes $φ (D) \equiv^{t} φ$ , φ ∈ Exp(F), of the multiplication operators φ :ψ ↦ φ ψ on Exp(F). A continuous operator T on $ℋ_{N b} (E)$ is PDE-preserving for a set ℙ ⊆...

On the first sign change in Mertens' theorem

Jan Büthe (2015)

Acta Arithmetica

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The function $\sum_{p \leq x} 1 / p - l o g l o g (x) - M$ is known to change sign infinitely often, but so far all calculated values are positive. In this paper we prove that the first sign change occurs well before exp(495.702833165).

On a result by Clunie and Sheil-Small

Dariusz Partyka, Ken-ichi Sakan (2012)

Annales Universitatis Mariae Curie-Sklodowska, sectio A – Mathematica

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In 1984 J. Clunie and T. Sheil-Small proved ([2, Corollary 5.8]) that for any complex-valued and sense-preserving injective harmonic mapping $F$ in the unit disk $𝔻$ , if $F (𝔻)$ is a convex domain, then the inequality $| G (z_{2}) - G (z_{1}) | < | H (z_{2}) - H (z_{1}) |$ holds for all distinct points $z_{1}, z_{2} \in 𝔻$ . Here $H$ and $G$ are holomorphic mappings in $𝔻$ determined by $F = H + \bar{G}$ , up to a constant function. We extend this inequality by replacing the unit disk by an arbitrary nonempty domain $Ω$ in $ℂ$ and improve it provided $F$ is additionally a quasiconformal mapping...

On a theorem of Lindelof

Vladimir Ya. Gutlyanskii, Olli Martio, Vladimir Ryazanov (2011)

Annales Universitatis Mariae Curie-Sklodowska, sectio A – Mathematica

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We give a quasiconformal version of the proof for the classical Lindelof theorem: Let $f$ map the unit disk $𝔻$ conformally onto the inner domain of a Jordan curve $𝒞$ : Then $𝒞$ is smooth if and only if arg $f^{'} (z)$ has a continuous extension to $\bar{𝔻}$ . Our proof does not use the Poisson integral representation of harmonic functions in the unit disk.

On some viscoelastic models

Pasquale Renno (1983)

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

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Sia $\mathcal{B}_{n}$ un sistema linearmente viscoelastico, omogeneo ed isotropo, caratterizzato dalla funzione di memoria $g_{n}(t)=\sum_{k=1}^{n}B_{k}\,\exp(-\beta_{k}t)$ , tipica di numerosi polimeri solidi. Si dimostra che la soluzione fondamentale $E_{n}$ dell’operatore integrodifferenziale che descrive i moti di $\mathcal{B}_{n}$ è, in ogni punto del suo supporto, maggiorata da quella relativa ad un opportuno solido standard $\mathcal{B}_{1}$ Di conseguenza, è possibile applicare all’analisi qualitativa dei moti di $\mathcal{B}_{n}$ alcuni risultati stabiliti in [10], quali proprietà asintotiche,...

Composition operator and Sobolev-Lorentz spaces $W L^{n, q}$

Stanislav Hencl, Luděk Kleprlík, Jan Malý (2014)

Studia Mathematica

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Let Ω,Ω’ ⊂ ℝⁿ be domains and let f: Ω → Ω’ be a homeomorphism. We show that if the composition operator $T_{f} : u \mapsto u \circ f$ maps the Sobolev-Lorentz space $W L^{n, q} (Ω^{'})$ to $W L^{n, q} (Ω)$ for some q ≠ n then f must be a locally bilipschitz mapping.

Sufficient Conditions for Integrability of Distortion Function Kf 1

Costantino Capozzoli (2009)

Bollettino dell'Unione Matematica Italiana

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Assume that $\Omega$ , $\Omega^{\prime}$ are planar domains and $f\colon\Omega\xrightarrow{\text{onto}}\Omega^{\prime}$ is a homeomorphism belonging to Sobolev space $W_{\text{loc}}^{1,1}(\Omega;\mathbb{R}^{2})$ with finite distortion. We prove that if the distortion function $K_{f}$ of $f$ satisfies the condition $\operatorname{dist}_{\text{EXP}}(K_{f},L^{\infty})<1$ , then the distortion function $K_{f^{-1}}$ of $f^{-1}$ belongs to $L^{1}_{\text{loc}}(\Omega^{\prime})$ . We show that this result is sharp in sense that the conclusion fails if $\operatorname{dist}_{\text{EXP}}(K_{f},L^{\infty})=1$ . Moreover, we prove that if the distortion function $K_{f}$ satisfies the condition $\operatorname{dist}_{\text{EXP}}(K_{f},L^{\infty})=\lambda$ for some $\lambda>0$ , then $K_{f^{-1}}$ belongs to $L^{p}_{\text{loc}}(\Omega^{\prime})$ for every $p\in(0,\frac{1}{2\lambda})$ . As special case of this result we show that if...

A nonsmooth exponential

Esteban Andruchow (2003)

Studia Mathematica

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Let ℳ be a type II₁ von Neumann algebra, τ a trace in ℳ, and L²(ℳ,τ) the GNS Hilbert space of τ. If L²(ℳ,τ)₊ is the completion of the set $ℳ_{s a}$ of selfadjoint elements, then each element ξ ∈ L²(ℳ,τ)₊ gives rise to a selfadjoint unbounded operator $L_{ξ}$ on L²(ℳ,τ). In this note we show that the exponential exp: L²(ℳ,τ)₊ → L²(ℳ,τ), $e x p (ξ) = e^{i L_{ξ}}$ , is continuous but not differentiable. The same holds for the Cayley transform $C (ξ) = (L_{ξ} - i) {(L_{ξ} + i)}^{- 1}$ . We also show that the unitary group $U_{ℳ} \subset L ² (ℳ, τ)$ with the strong operator topology is not an...

On a modification of the Poisson integral operator

Dariusz Partyka (2011)

Annales Universitatis Mariae Curie-Sklodowska, sectio A – Mathematica

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Given a quasisymmetric automorphism $γ$ of the unit circle $𝕋$ we define and study a modification $P_{γ}$ of the classical Poisson integral operator in the case of the unit disk $𝔻$ . The modification is done by means of the generalized Fourier coefficients of $γ$ . For a Lebesgue’s integrable complexvalued function $f$ on $𝕋$ , $P_{γ} [f]$ is a complex-valued harmonic function in $𝔻$ and it coincides with the classical Poisson integral of $f$ provided $γ$ is the identity mapping on $𝕋$ . Our considerations are motivated by...

Isomorphisms of Cartesian Products of ℓ-Power Series Spaces

E. Karapınar, M. Yurdakul, V. Zahariuta (2006)

Bulletin of the Polish Academy of Sciences. Mathematics

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Let ℓ be a Banach sequence space with a monotone norm $∥ \cdot ∥_{ℓ}$ , in which the canonical system $(e_{i})$ is a normalized symmetric basis. We give a complete isomorphic classification of Cartesian products $E_{0}^{ℓ} (a) \times E_{\infty}^{ℓ} (b)$ where $E_{0}^{ℓ} (a) = K^{ℓ} (e x p (- p^{- 1} a_{i}))$ and $E_{\infty}^{ℓ} (b) = K^{ℓ} (e x p (p a_{i}))$ are finite and infinite ℓ-power series spaces, respectively. This classification is the generalization of the results by Chalov et al. [Studia Math. 137 (1999)] and Djakov et al. [Michigan Math. J. 43 (1996)] by using the method of compound linear topological invariants developed by...

On some viscoelastic models

Pasquale Renno (1983)

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

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Groups of given intermediate word growth

Laurent Bartholdi, Anna Erschler (2014)

Annales de l’institut Fourier

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We show that there exists a finitely generated group of growth $\sim f$ for all functions $f : ℝ_{+} \to ℝ_{+}$ satisfying $f (2 R) \leq f {(R)}^{2} \leq f (η_{+} R)$ for all $R$ large enough and $η_{+} \approx 2.4675$ the positive root of $X^{3} - X^{2} - 2 X - 4$ . Set $α_{-} = log 2 / log η_{+} \approx 0.7674$ ; then all functions that grow uniformly faster than $exp (R^{α_{-}})$ are realizable as the growth of a group. We also give a family of sum-contracting branched groups of growth $\sim exp (R^{α})$ for a dense set of $α \in [α_{-}, 1]$ .

Existence of graphs with sub exponential transitions probability decay and applications

Clément Rau (2010)

Bulletin de la Société Mathématique de France

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In this paper, we recall the existence of graphs with bounded valency such that the simple random walk has a return probability at time $n$ at the origin of order $exp (- n^{α}),$ for fixed $α \in [0, 1 [$ and with Følner function $exp (n^{\frac{2 α}{1 - α}})$ . This result was proved by Erschler (see [4], [3]); we give a more detailed proof of this construction in the appendix. In the second part, we give an application of the existence of such graphs. We obtain bounds of the correct order for some functional of the local time of a simple random...

Moser's Inequality for a class of integral operators

Finbarr Holland, David Walsh (1995)

Studia Mathematica

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Let 1 < p < ∞, q = p/(p-1) and for $f \in L^{p} (0, \infty)$ define $F (x) = (1 / x) ʃ_{0}^{x} f (t) d t$ , x > 0. Moser’s Inequality states that there is a constant $C_{p}$ such that $s u p_{a \leq 1} s u p_{f \in B_{p}} ʃ_{0}^{\infty} e x p [a x^{q} {| F (x) |}^{q} - x] d x = C_{p}$ where $B_{p}$ is the unit ball of $L^{p}$ . Moreover, the value a = 1 is sharp. We observe that $F = K_{1}$ f where the integral operator $K_{1}$ has a simple kernel K. We consider the question of for what kernels K(t,x), 0 ≤ t, x < ∞, this result can be extended, and proceed to discuss this when K is non-negative and homogeneous of degree -1. A sufficient condition on K is found for...

Soliton solutions for quasilinear Schrödinger equation with critical exponential growth in $ℝ^{N}$

Caisheng Chen, Hongxue Song (2016)

Applications of Mathematics

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In this work, we study the existence of nonnegative and nontrivial solutions for the quasilinear Schrödinger equation $- Δ_{N} u + b {| u |}^{N - 2} u - Δ_{N} (u^{2}) u = h (u), x \in ℝ^{N},$ where $Δ_{N}$ is the $N$ -Laplacian operator, $h (u)$ is continuous and behaves as $exp (α | u |^{N / (N - 1)})$ when $| u | \to \infty$ . Using the Nehari manifold method and the Schwarz symmetrization with some special techniques, the existence of a nonnegative and nontrivial solution $u (x) \in W^{1, N} (ℝ^{N})$ with $u (x) \to 0$ as $| x | \to \infty$ is established.

A tight quantitative version of Arrow’s impossibility theorem

Nathan Keller (2012)

Journal of the European Mathematical Society

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The well-known Impossibility Theorem of Arrow asserts that any generalized social welfare function (GSWF) with at least three alternatives, which satisfies Independence of Irrelevant Alternatives (IIA) and Unanimity and is not a dictatorship, is necessarily non-transitive. In 2002, Kalai asked whether one can obtain the following quantitative version of the theorem: For any $ϵ > 0$ , there exists $δ = δ (ϵ)$ such that if a GSWF on three alternatives satisfies the IIA condition and its probability of...

Quasi-polynomial mixing of the 2D stochastic Ising model with “plus” boundary up to criticality

Eyal Lubetzky, Fabio Martinelli, Allan Sly, Fabio Lucio Toninelli (2013)

Journal of the European Mathematical Society

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We considerably improve upon the recent result of [37] on the mixing time of Glauber dynamics for the 2D Ising model in a box of side $L$ at low temperature and with random boundary conditions whose distribution $P$ stochastically dominates the extremal plus phase. An important special case is when $P$ is concentrated on the homogeneous all-plus configuration, where the mixing time $T_{M I X}$ is conjectured to be polynomial in $L$ . In [37] it was shown that for a large enough inverse-temperature $β$ and...

On sets of confluent and related mappings in the space $Y^{X}$

T. Maćkowiak (1976)

Colloquium Mathematicae

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On $L_{p} - L_{q}$ boundedness for convolutions with kernels having singularities on a sphere

Alexey N. Karapetyants (2001)

Studia Mathematica

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For the convolution operators $A_{a}^{α}$ with symbols ${a (| ξ |) | ξ |}^{- α} e x p i | ξ |$ , 0 ≤ Re α < n, $a (| ξ |) \in L_{\infty}$ , we construct integral representations and give the exact description of the set of pairs (1/p,1/q) for which the operators are bounded from $L_{p}$ to $L_{q}$ .

Quantum expanders and geometry of operator spaces

Gilles Pisier (2014)

Journal of the European Mathematical Society

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We show that there are well separated families of quantum expanders with asymptotically the maximal cardinality allowed by a known upper bound. This has applications to the “growth" of certain operator spaces: It implies asymptotically sharp estimates for the growth of the multiplicity of $M_{N}$ -spaces needed to represent (up to a constant $C > 1$ ) the $M_{N}$ -version of the $n$ -dimensional operator Hilbert space $O H_{n}$ as a direct sum of copies of $M_{N}$ . We show that, when $C$ is close to 1, this multiplicity grows...

Scaling limit and cube-root fluctuations in SOS surfaces above a wall

Pietro Caputo, Eyal Lubetzky, Fabio Martinelli, Allan Sly, Fabio Lucio Toninelli (2016)

Journal of the European Mathematical Society

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Consider the classical $(2 + 1)$ -dimensional Solid-On-Solid model above a hard wall on an $L \times L$ box of $ℤ^{2}$ . The model describes a crystal surface by assigning a non-negative integer height $η_{x}$ to each site $x$ in the box and 0 heights to its boundary. The probability of a surface configuration $η$ is proportional to $\exp (- β ℋ (η))$ , where $β$ is the inverse-temperature and $ℋ (η)$ sums the absolute values of height differences between neighboring sites. We give a full description of the shape of the SOS surface for low enough...