Prepublicacions del Centre de Recerca Matemàtica: Recent submissions
Now showing items 21-40 of 619
Realization and characterization of modulus of smoothness in weighted Lebesgue spaces
We obtain a characterization of modulus of smoothnes of fractional order in the Lebesgue spaces \(L_{\omega}^{p}\), \(1 < p < \infty\), with weights \(\omega\) satisfying the Muckenhoupt’s \(A_{p}\) condition. Also, a ...
The Hardy-Littlewood-Stein inequality for generalized Hardy and Bellman type averages
Hardy-Littlwood-Stein inequality with the averages of Hardy and Bellman type, a kind of generalized mean of Fourier coefficients of
The perils of thresholding
The thresholding of time series of activity or intensity is frequently used to define and differentiate events. This is either implicit, for example due to resolution limits, or explicit, in order to filter certain small ...
Weighted norm inequalities for convolution and Riesz potential
In this paper, we prove analogues of O'\''Neil'\''s inequalities for the convolution in the weighted Lebesgue spaces. We also establish the weighted two-sided norm inequalities for the potential operator.
Uniform hyperbolicity of the curve graph via surgery sequences
We prove that the curve graph $ \calC^{(1)}(S)$ is Gromov-hyperbolic with a constant of hyperbolicity independent of the surface $ S$ . The proof is based on the proof of hyperbolicity of the free splitting complex by ...
The phenomenon of apparent disappearance in the marine bacteriophage dynamics
It was observed, that in aquatic microbial systems, high magnitude variations in abundance, such as sudden blooms alternating with comparatively long periods of very low abundance (apparent disappearance'\'''\'') are ...
Rational families of instanton bundles on $ {P}^{2n+1}$
This paper is devoted to the theory of symplectic instanton bundles on an odd dimensional projective space $ {P}^{2n+1}$ with $ n\ge 2$ . The investigation of '\''t Hooft instanton bundles that were introduced by Ottaviani ...
Quantum cohomology of toric orbifolds
For any compact toric orbifold (smooth proper Deligne-Mumford toric stack) $ Y$ with projective coarse moduli space, we show that the quantum cohomology $ QH(Y)$ is canonically isomorphic (in a formal neighborhood of a ...
Ulyanov-type inequalities between Lorentz-Zygmund spaces
We establish inequalities of Ulyanov-type for moduli of smoothness relating the source Lorentz-Zygmund space $ \, L^{p,r}(\log L)^{\alpha -\gamma},\, \gamma >0,$ and the target space $ \, L^{p^*,s}(\log L)^\alpha $ over $ ...
The number of medium amplitude limit cycles of some generalized Liénard systems
We will consider two special families of polynomial perturbations of the linear center. For the resulting perturbed systems, which are generalized Liénard systems, we provide the exact upper bound for the number of limit ...
Weighted Fractional Bernstein'\''s inequalities and their applications
This paper studies the following weighted, fractional Bernstein inequality for spherical polynomials on $ \sph$ : \begin{equation}\label{4-1-TD-ab} \|(-\Delta_0)^{r/2} f\|_{p,w}\leq C_w n^{r} \|f\|_{p,w}, \ \ \forall f\in ...
Unbounded quasitraces, stable finiteness and pure infiniteness
We prove that if $ A$ is a $ \sigma$ -unital exact $ C^*$ -algebra of real rank zero, then every state on $ K_0(A)$ is induced by a 2-quasitrace on $ A$ . This yields a generalisation of Rainone'\''s work on pure infiniteness ...
Tests for injectivity of modules over commutative rings
It is proved that a module $ M$ over a commutative noetherian ring $ R$ is injective if $ \mathrm{Ext}_{R}^{i}((R/{\mathfrak p})_{\mathfrak p},M)=0$ for every $ i\ge 1$ and every prime ideal $ \mathfrak{p}$ in~$ R$ . This ...
Tensor products and regularity properties of Cuntz semigroups
The Cuntz semigroup of a \ca{} is an important invariant in the structure and classification theory of \ca{s}. It captures more information than $ K$ -theory but is often more delicate to handle. We systematically study ...
The effect of fixing node strengths on multi-edge networks
Complex networks grow subject to structural constraints which affect their measurable properties. Assessing the effect that such constraints impose on their observables is thus a crucial aspect to be taken into account in ...
Poincaré--Pontryagin--Melnikov functions for a class of perturbed planar Hamiltonian equations
In this paper we extend a well-known algorithm for studying higher order Poincaré--Pontryagin--Melnikov functions of polynomial perturbed Hamiltonian equations. We consider a family of unperturbed equations whose associated ...
Vector bundles of low rank on a multiprojective space
In this paper we construct vector bundles over a multiprojective space and study their properties. We first set out to establish the existence of monads on a multiprojective space $ \PP^n\times\PP^m$ , for all integers $ ...
Weighted D-T moduli revisited and applied
$ f\in L_p[-1,1]\cap C^{r-1}(-1,1)$ , $ r\ge1$ , that have an $ (r-1)$ st absolutely continuous derivative in $ (-1,1)$ and such that $ \varphi^rf^{(r)}$ is in $ L_p[-1,1]$ , where $ \varphi(x)=(1-x^2)^{1/2}$ . These moduli ...
Polynomial approximation in rearrangement invariant quasi Banach spaces on the unit circle
In this work work we obtain some Jackson type direct theorem and sharp converse theorem of polynomial approximation with respect to fractional order moduli of smoothness in rearrangement invariant quasi Banach spaces on ...
