Results 41 to 50 of about 3,883 (229)

Two Erdos problems on lacunary sequences: Chromatic number and Diophantine approximation

open access: yes, 2007
Let ${n_k}$ be an increasing lacunary sequence, i.e., $n_{k+1}/n_k>1+r$ for some $r>0$. In 1987, P. Erdos asked for the chromatic number of a graph $G$ on the integers, where two integers $a,b$ are connected by an edge iff their difference $|a-b|$ is in ...
Peres, Yuval, Schlag, Wilhelm
core   +1 more source

On some lacunary difference sequence spaces defined by a sequence of Orlicz functions and q-lacunary Δnm-statistical convergence

open access: yesAnalele Stiintifice ale Universitatii Ovidius Constanta: Seria Matematica, 2012
In this article, we introduce the lacunary difference sequence spaces w0(M, θ, Δnm, p, q), w1(M, θ, Δnm, p, q) and w∞(M, θ, Δnm, p, q) using a sequence M = (Mk) of Orlicz functions and investigate some relevant properties of these spaces. Then, we define
Tripathy Binod Chandra, Dutta Hemen
doaj   +1 more source

Star Discrepancy Bounds of Double Infinite Matrices induced by Lacunary Systems [PDF]

open access: yes, 2014
In 2001 Heinrich, Novak, Wasilkowski and Wo\'zniakowski proved that the inverse of the star discrepancy satisfies $n(d,\varepsilon)\leq c_{\abs}d \varepsilon^{-2}$ by showing that there exists a set of points in $[0,1)^d$ whose star-discrepancy is ...
Löbbe, Thomas
core  

On Metric Ramsey-type Dichotomies

open access: yes, 2002
The classical Ramsey theorem, states that every graph contains either a large clique or a large independent set. Here we investigate similar dichotomic phenomena in the context of finite metric spaces.
Bartal, Yair   +3 more
core   +3 more sources

The dimension of well approximable numbers

open access: yesJournal of the London Mathematical Society, Volume 113, Issue 1, January 2026.
Abstract In this survey article, we explore a central theme in Diophantine approximation inspired by a celebrated result of Besicovitch on the Hausdorff dimension of well approximable real numbers. We outline some of the key developments stemming from Besicovitch's result, with a focus on the mass transference principle, ubiquity and Diophantine ...
Victor Beresnevich, Sanju Velani
wiley   +1 more source

The Cesáro Lacunary Ideal bounded linear operator of χ2 - of φ-statistical vector valued defined by a bounded linear operator of interval numbers [PDF]

open access: yesSongklanakarin Journal of Science and Technology (SJST), 2017
Let   uv mn A be a sequence of bounded linear operators from a separable Banach metric space of (X , 0) into a Banach metric space (Y, 0). Suppose that φ ∈ Φ is a countable fundamental set of X and the ideal I - of subsets \mathbb{N} x \mathbb{N ...
Deepmala   +2 more
doaj   +1 more source

A pointwise ergodic theorem along return times of rapidly mixing systems

open access: yesBulletin of the London Mathematical Society, Volume 57, Issue 12, Page 3730-3748, December 2025.
Abstract We introduce a new class of sparse sequences that are ergodic and pointwise universally L2$L^2$‐good for ergodic averages; that is, sequences along which the ergodic averages converge almost surely to the projection to invariant functions.
Sebastián Donoso   +2 more
wiley   +1 more source

Surface‐Exposed Pd Nanocluster Confined within a Ring‐Shaped Polyoxometalate for Selective Hydrogenation

open access: yesAdvanced Science, Volume 12, Issue 38, October 13, 2025.
A small Pd nanocluster is successfully prepared within a ring‐shaped polyoxometalate via a mild solid‐state reduction process. The resulting surface‐exposed Pd nanocluster functions as a robust heterogeneous reusable catalyst, enabling highly chemoselective hydrogenation of substrates containing multiple reducible functional groups via selective ...
Rui Xi   +8 more
wiley   +1 more source

Ferrimagnetic Structure of 3C Pyrrhotite (Fe7S8) From Neutron Diffraction

open access: yesGeochemistry, Geophysics, Geosystems, Volume 26, Issue 9, September 2025.
Abstract Pyrrhotite is a paleomagnetically important magnetic mineral in many geological settings. It forms numerous polytypes with different stacking patterns of the NiAs structure along the crystallographic c axis to produce different vacancy‐ordered superstructures.
Chin‐Wei Wang   +2 more
wiley   +1 more source

DFT Study of Halide‐Free Mechanism of the CO2 Cycloaddition onto Epoxide by [PW11O39{Zn(H2O)}]5−: Evidences for the Formation of Hydrogencarbonate Intermediates

open access: yesChemCatChem, Volume 17, Issue 15, August 7, 2025.
The computational study, sustained by experimental data, of the catalytic activity of [PW11O39{Zn(H2O)}]5− in CO2 cycloaddition to epoxide highlights how the carbonic anhydrase‐like character of this complex couples to the versatile binding properties of the polyoxometalate in this reaction pathway. Abstract The intertwined experimental and theoretical
Jingjing Ren   +3 more
wiley   +1 more source

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