Search results for " 46"
showing 10 items of 140 documents
Two-dimensional Banach spaces with polynomial numerical index zero
2009
We study two-dimensional Banach spaces with polynomial numerical indices equal to zero.
Adjacency matrices of random digraphs: singularity and anti-concentration
2017
Let ${\mathcal D}_{n,d}$ be the set of all $d$-regular directed graphs on $n$ vertices. Let $G$ be a graph chosen uniformly at random from ${\mathcal D}_{n,d}$ and $M$ be its adjacency matrix. We show that $M$ is invertible with probability at least $1-C\ln^{3} d/\sqrt{d}$ for $C\leq d\leq cn/\ln^2 n$, where $c, C$ are positive absolute constants. To this end, we establish a few properties of $d$-regular directed graphs. One of them, a Littlewood-Offord type anti-concentration property, is of independent interest. Let $J$ be a subset of vertices of $G$ with $|J|\approx n/d$. Let $\delta_i$ be the indicator of the event that the vertex $i$ is connected to $J$ and define $\delta = (\delta_1, …
Relaciones entre la monarquía Hispánica y el reino de Galicia: el papel de los Diputados Generales del Reino
2020
Oligarquización, oligarquías y gobierno urbano en el Oviedo de los Austrias
2020
El sentimiento de superioridad de los jesuitas tras la extinción de la Compañía de Jesús
2020
Construcción de puentes y avenidas fluviales: algunos debates técnicos en el academicismo ilustrado del Reino de Valencia
2020
Con el afianzamiento de las políticas reformistas y la consolidación de las academias de bellas artes, durante el último tercio del siglo XVIII se desarrolló una creciente polémica entre los arquitectos y los maestros de obra en torno a la proyección y diseño de obra civil, particularmente la relacionada con ambientes fluviales. En este artículo se valora, con diferentes ejemplos, la incidencia de este debate en la proyección de puentes y su capacidad de resistencia a las avenidas fluviales. During the last third of the 18th century, reformist policies and the consolidation of the fine arts academies were consolidated. This fact affected the architects and the master builders with a policy …
Ferrer del Río: Rodrigo de Mendoza, noble y coleccionista del Renacimiento
2020
Isometric embeddings of snowflakes into finite-dimensional Banach spaces
2016
We consider a general notion of snowflake of a metric space by composing the distance by a nontrivial concave function. We prove that a snowflake of a metric space $X$ isometrically embeds into some finite-dimensional normed space if and only if $X$ is finite. In the case of power functions we give a uniform bound on the cardinality of $X$ depending only on the power exponent and the dimension of the vector space.
Frame-related Sequences in Chains and Scales of Hilbert Spaces
2022
Frames for Hilbert spaces are interesting for mathematicians but also important for applications in, e.g., signal analysis and physics. In both mathematics and physics, it is natural to consider a full scale of spaces, and not only a single one. In this paper, we study how certain frame-related properties of a certain sequence in one of the spaces, such as completeness or the property of being a (semi-) frame, propagate to the other ones in a scale of Hilbert spaces. We link that to the properties of the respective frame-related operators, such as analysis or synthesis. We start with a detailed survey of the theory of Hilbert chains. Using a canonical isomorphism, the properties of frame se…
On singular integral and martingale transforms
2007
Linear equivalences of norms of vector-valued singular integral operators and vector-valued martingale transforms are studied. In particular, it is shown that the UMD(p)-constant of a Banach space X equals the norm of the real (or the imaginary) part of the Beurling-Ahlfors singular integral operator, acting on the X-valued L^p-space on the plane. Moreover, replacing equality by a linear equivalence, this is found to be the typical property of even multipliers. A corresponding result for odd multipliers and the Hilbert transform is given.