Topological countability in Brelot potential theory

Thomas E. Armstrong

Displaying similar documents to “Topological countability in Brelot potential theory”

Some properties of the balayage of measures on a harmonic space

Corneliu Constantinescu (1967)

Annales de l'institut Fourier

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On démontre plusieurs théorèmes concernant le balayage des mesures sur un espace harmonique satisfaisant aux axiomes de Bauer, parmi lesquels nous indiquons les suivants : a) la balayée $μ_{A \cup B}$ d’une mesure $μ$ sur la réunion $μ^{A} \lor μ^{B}$ (dans l’espace de Riesz de mesure) ; b) $ϵ_{x}^{A} \neq ϵ_{x}$ caractérise l’effilement de $A$ en $x$ ; c) il existe un potentiel fini et continue $p$ tel que pour tout ensemble $A {x | {\hat{R}}_{p} (x) < p (x)}$ est exactement l’ensemble des points où $A$ est effilé ; d) $μ^{A}$ est portée par la fermeture fine de $A$ ; e) si $A$ et $B$ sont...

Uniform bounds for quotients of Green functions on $C^{1, 1}$ -domains

H. Hueber, M. Sieveking (1982)

Annales de l'institut Fourier

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Let $Δ u = Σ_{i} \frac{\partial^{2}}{\partial_{x_{i}}^{2}}$ , $L u = Σ_{i, j} a_{i j} \frac{\partial^{2}}{\partial x_{i} \partial x_{j}} u + Σ_{i} b_{i} \frac{\partial}{\partial x_{i}} u + c u$ be elliptic operators with Hölder continuous coefficients on a bounded domain $Ω \subset R^{n}$ of class $C^{1, 1}$ . There is a constant $c > 0$ depending only on the Hölder norms of the coefficients of $L$ and its constant of ellipticity such that $c^{- 1} G_{Δ}^{Ω} \leq G_{L}^{Ω} \leq c G_{Δ}^{Ω} on Ω \times Ω,$ where $γ_{Δ}^{Ω}$ (resp. $G_{L}^{Ω}$ ) are the Green functions of $Δ$ (resp. $L$ ) on $Ω$ .

A class of functions containing polyharmonic functions in ℝⁿ

V. Anandam, M. Damlakhi (2003)

Annales Polonici Mathematici

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Some properties of the functions of the form $v (x) = \sum_{i = 0}^{m} {| x |}^{i} h_{i} (x)$ in ℝⁿ, n ≥ 2, where each $h_{i}$ is a harmonic function defined outside a compact set, are obtained using the harmonic measures.

On the integral representation of finely superharmonic functions

Abderrahim Aslimani, Imad El Ghazi, Mohamed El Kadiri (2019)

Commentationes Mathematicae Universitatis Carolinae

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In the present paper we study the integral representation of nonnegative finely superharmonic functions in a fine domain subset $U$ of a Brelot $𝒫$ -harmonic space $Ω$ with countable base of open subsets and satisfying the axiom $D$ . When $Ω$ satisfies the hypothesis of uniqueness, we define the Martin boundary of $U$ and the Martin kernel $K$ and we obtain the integral representation of invariant functions by using the kernel $K$ . As an application of the integral representation we extend to the cone...

Landau's theorem for p-harmonic mappings in several variables

Sh. Chen, S. Ponnusamy, X. Wang (2012)

Annales Polonici Mathematici

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A 2p-times continuously differentiable complex-valued function f = u + iv in a domain D ⊆ ℂ is p-harmonic if f satisfies the p-harmonic equation $Δ^{p} f = 0$ , where p (≥ 1) is a positive integer and Δ represents the complex Laplacian operator. If Ω ⊂ ℂⁿ is a domain, then a function $f : Ω \to ℂ^{m}$ is said to be p-harmonic in Ω if each component function $f_{i}$ (i∈ 1,...,m) of $f = (f ₁, . . ., f_{m})$ is p-harmonic with respect to each variable separately. In this paper, we prove Landau and Bloch’s theorem for a class of p-harmonic mappings...

A poset of topologies on the set of real numbers

Vitalij A. Chatyrko, Yasunao Hattori (2013)

Commentationes Mathematicae Universitatis Carolinae

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On the set $ℝ$ of real numbers we consider a poset $𝒫_{τ} (ℝ)$ (by inclusion) of topologies $τ (A)$ , where $A \subseteq ℝ$ , such that $A_{1} \supseteq A_{2}$ iff $τ (A_{1}) \subseteq τ (A_{2})$ . The poset has the minimal element $τ (ℝ)$ , the Euclidean topology, and the maximal element $τ (\emptyset)$ , the Sorgenfrey topology. We are interested when two topologies $τ_{1}$ and $τ_{2}$ (especially, for $τ_{2} = τ (\emptyset)$ ) from the poset define homeomorphic spaces $(ℝ, τ_{1})$ and $(ℝ, τ_{2})$ . In particular, we prove that for a closed subset $A$ of $ℝ$ the space $(ℝ, τ (A))$ is homeomorphic to the Sorgenfrey line $(ℝ, τ (\emptyset))$ iff $A$ is countable. We study also common...

On Ditkin sets

T. Muraleedharan, K. Parthasarathy (1996)

Colloquium Mathematicae

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In the study of spectral synthesis S-sets and C-sets (see Rudin [3]; Reiter [2] uses the terminology Wiener sets and Wiener-Ditkin sets respectively) have been discussed extensively. A new concept of Ditkin sets was introduced and studied by Stegeman in [4] so that, in Reiter’s terminology, Wiener-Ditkin sets are precisely sets which are both Wiener sets and Ditkin sets. The importance of such sets in spectral synthesis and their connection to the C-set-S-set problem (see Rudin [3])...

Axiomatic theory of harmonic functions. Balayage

Nicu Boboc, Corneliu Constantinescu, A. Cornea (1965)

Annales de l'institut Fourier

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Dans une axiomatique des fonctions harmoniques un peu plus générale que celle de H. Bauer, on démontre les relations suivantes : $R_{s + t}^{A} = R_{s}^{A} + R_{t}^{A},$ $R_{s}^{A \cup B} + R_{s}^{A \cap B} \leq R_{s}^{A} + R_{s}^{B},$ $A_{n} ↑ A, S_{n} ↑ s \Rightarrow R_{s_{n}}^{A_{n}} ↑ R_{s}^{A},$ où $A$ , $B$ , $A_{n}$ , (resp. $s$ , $t$ , $s_{n}$ ) sont des ensembles (resp. fonctions hyperharmoniques non-négatives) arbitraires. Les mêmes relations sont valables pour $\hat{R}$ . On démontre aussi que la relation $\int^{*} s d μ^{A} = \int^{*} {\hat{R}}_{s}^{A} d μ$ a lieu si l’espace de base a une base dénombrable ou si l’axiome $D$ de M. Brelot est satisfait,...