On the cardinality of power homogeneous Hausdorff spaces

G. J. Ridderbos

Displaying similar documents to “On the cardinality of power homogeneous Hausdorff spaces”

Some dimensional results for a class of special homogeneous Moran sets

Xiaomei Hu (2016)

Czechoslovak Mathematical Journal

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We construct a class of special homogeneous Moran sets, called ${m_{k}}$ -quasi homogeneous Cantor sets, and discuss their Hausdorff dimensions. By adjusting the value of ${m_{k}}_{k \geq 1}$ , we constructively prove the intermediate value theorem for the homogeneous Moran set. Moreover, we obtain a sufficient condition for the Hausdorff dimension of homogeneous Moran sets to assume the minimum value, which expands earlier works.

Positively homogeneous functions and the Łojasiewicz gradient inequality

Alain Haraux (2005)

Annales Polonici Mathematici

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It is quite natural to conjecture that a positively homogeneous function with degree d ≥ 2 on $ℝ^{N}$ satisfies the Łojasiewicz gradient inequality with exponent θ = 1/d without any need for an analyticity assumption. We show that this property is true under some additional hypotheses, but not always, even for N = 2.

Classifying homogeneous ultrametric spaces up to coarse equivalence

Taras Banakh, Dušan Repovš (2016)

Colloquium Mathematicae

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For every metric space X we introduce two cardinal characteristics $c o v^{♭} (X)$ and $c o v^{♯} (X)$ describing the capacity of balls in X. We prove that these cardinal characteristics are invariant under coarse equivalence, and that two ultrametric spaces X,Y are coarsely equivalent if $c o v^{♭} (X) = c o v^{♯} (X) = c o v^{♭} (Y) = c o v^{♯} (Y)$ . This implies that an ultrametric space X is coarsely equivalent to an isometrically homogeneous ultrametric space if and only if $c o v^{♭} (X) = c o v^{♯} (X)$ . Moreover, two isometrically homogeneous ultrametric spaces X,Y are coarsely equivalent if and...

Besov spaces on spaces of homogeneous type and fractals

Dachun Yang (2003)

Studia Mathematica

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Let Γ be a compact d-set in ℝⁿ with 0 < d ≤ n, which includes various kinds of fractals. The author shows that the Besov spaces $B_{p q}^{s} (Γ)$ defined by two different and equivalent methods, namely, via traces and quarkonial decompositions in the sense of Triebel are the same spaces as those obtained by regarding Γ as a space of homogeneous type when 0 < s < 1, 1 < p < ∞ and 1 ≤ q ≤ ∞.

On convergence sets of divergent power series

Buma L. Fridman, Daowei Ma, Tejinder S. Neelon (2012)

Annales Polonici Mathematici

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A nonlinear generalization of convergence sets of formal power series, in the sense of Abhyankar-Moh [J. Reine Angew. Math. 241 (1970)], is introduced. Given a family $y = φ_{s} (t, x) = s b ₁ (x) t + b ₂ (x) t ² + \dots$ of analytic curves in ℂ × ℂⁿ passing through the origin, $C o n v_{φ} (f)$ of a formal power series f(y,t,x) ∈ ℂ[[y,t,x]] is defined to be the set of all s ∈ ℂ for which the power series $f (φ_{s} (t, x), t, x)$ converges as a series in (t,x). We prove that for a subset E ⊂ ℂ there exists a divergent formal power series f(y,t,x) ∈ ℂ[[y,t,x]] such that $E = C o n v_{φ} (f)$ if...

Lacunary formal power series and the Stern-Brocot sequence

Jean-Paul Allouche, Michel Mendès France (2013)

Acta Arithmetica

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Let $F (X) = \sum_{n \geq 0} {(- 1)}^{ε ₙ} X^{- λ ₙ}$ be a real lacunary formal power series, where εₙ = 0,1 and $λ_{n + 1} / λ ₙ > 2$ . It is known that the denominators Qₙ(X) of the convergents of its continued fraction expansion are polynomials with coefficients 0, ±1, and that the number of nonzero terms in Qₙ(X) is the nth term of the Stern-Brocot sequence. We show that replacing the index n by any 2-adic integer ω makes sense. We prove that $Q_{ω} (X)$ is a polynomial if and only if ω ∈ ℤ. In all the other cases $Q_{ω} (X)$ is an infinite formal power series; we discuss...

On some ordered continua of power $2^{a l e p h_{0}}$ containing a dense subset of power $ℵ_{1}$

Josef Novák (1951)

Czechoslovak Mathematical Journal

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Homogeneity and non-coincidence of Hausdorff and box dimensions for subsets of ℝⁿ

Anders Nilsson, Peter Wingren (2007)

Studia Mathematica

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A class of subsets of ℝⁿ is constructed that have certain homogeneity and non-coincidence properties with respect to Hausdorff and box dimensions. For each triple (r,s,t) of numbers in the interval (0,n] with r < s < t, a compact set K is constructed so that for any non-empty subset U relatively open in K, we have $(d i m_{H} (U), {\underset{̲}{d i m}}_{B} (U), {\bar{d i m}}_{B} (U)) = (r, s, t)$ . Moreover, $2^{- n} \leq H^{r} (K) \leq 2 n^{r / 2}$ .

$L^{p} (ℝ ⁿ)$ boundedness for the commutator of a homogeneous singular integral operator

Guoen Hu (2003)

Studia Mathematica

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The commutator of a singular integral operator with homogeneous kernel Ω(x)/|x|ⁿ is studied, where Ω is homogeneous of degree zero and has mean value zero on the unit sphere. It is proved that $Ω \in L {(l o g L)}^{k + 1} (S^{n - 1})$ is a sufficient condition for the kth order commutator to be bounded on $L^{p} (ℝ ⁿ)$ for all 1 < p < ∞. The corresponding maximal operator is also considered.

On the nontrivial solvability of systems of homogeneous linear equations over $ℤ$ in ZFC

Jan Šaroch (2020)

Commentationes Mathematicae Universitatis Carolinae

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Motivated by the paper by H. Herrlich, E. Tachtsis (2017) we investigate in ZFC the following compactness question: for which uncountable cardinals $κ$ , an arbitrary nonempty system $S$ of homogeneous $ℤ$ -linear equations is nontrivially solvable in $ℤ$ provided that each of its subsystems of cardinality less than $κ$ is nontrivially solvable in $ℤ$ ?

On highly nonintegrable functions and homogeneous polynomials

P. Wojtaszczyk (1997)

Annales Polonici Mathematici

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We construct a sequence of homogeneous polynomials on the unit ball $_{d}$ in $ℂ^{d}$ which are big at each point of the unit sphere . As an application we construct a holomorphic function on $_{d}$ which is not integrable with any power on the intersection of $_{d}$ with any complex subspace.

On the behavior close to the unit circle of the power series whose coefficients are squared Möbius function values

Oleg Petrushov (2015)

Acta Arithmetica

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We consider the behavior of the power series $_{0} (z) = \sum_{n = 1}^{\infty} μ^{2} (n) z^{n}$ as z tends to $e (β) = e^{2 π i β}$ along a radius of the unit circle. If β is irrational with irrationality exponent 2 then $_{0} (e (β) r) = O ({(1 - r)}^{- 1 / 2 - ε})$ . Also we consider the cases of higher irrationality exponent. We prove that for each δ there exist irrational numbers β such that $_{0} (e (β) r) = Ω ({(1 - r)}^{- 1 + δ})$ .

Naturally reductive homogeneous $(α, β)$ -metric spaces

M. Parhizkar, H.R. Salimi Moghaddam (2021)

Archivum Mathematicum

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In the present paper we study naturally reductive homogeneous $(α, β)$ -metric spaces. We show that for homogeneous $(α, β)$ -metric spaces, under a mild condition, the two definitions of naturally reductive homogeneous Finsler space, given in the literature, are equivalent. Then, we compute the flag curvature of naturally reductive homogeneous $(α, β)$ -metric spaces.

Type and cotype of operator spaces

Hun Hee Lee (2008)

Studia Mathematica

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We consider two operator space versions of type and cotype, namely $S_{p}$ -type, $S_{q}$ -cotype and type (p,H), cotype (q,H) for a homogeneous Hilbertian operator space H and 1 ≤ p ≤ 2 ≤ q ≤ ∞, generalizing “OH-cotype 2” of G. Pisier. We compute type and cotype of some Hilbertian operator spaces and $L_{p}$ spaces, and we investigate the relationship between a homogeneous Hilbertian space H and operator spaces with cotype (2,H). As applications we consider operator space versions of generalized little...

The (dis)connectedness of products of Hausdorff spaces in the box topology

Vitalij A. Chatyrko (2021)

Commentationes Mathematicae Universitatis Carolinae

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In this paper the following two propositions are proved: (a) If $X_{α}$ , $α \in A$ , is an infinite system of connected spaces such that infinitely many of them are nondegenerated completely Hausdorff topological spaces then the box product $□_{α \in A} X_{α}$ can be decomposed into continuum many disjoint nonempty open subsets, in particular, it is disconnected. (b) If $X_{α}$ , $α \in A$ , is an infinite system of Brown Hausdorff topological spaces then the box product $□_{α \in A} X_{α}$ is also Brown Hausdorff, and hence, it is connected. A space...