In this paper, a new construction of vertex algebras from more general vertex operators is given and a notion of quasi module for vertex algebras is introduced and studied. More specifically, a notion of quasi local subset(space) of Hom (W,W ((x))) for any vector space W is introduced and studied, generalizing the notion of usual locality in the most possible way, and it is proved that on any m...

We show that if Y is a separable subspace of a Banach space X such that both X and the quotient X/Y have Cp-smooth Lipschitz bump functions, and U is a bounded open subset of X, then, for every uniformly continuous function f : Y ∩U → R and every ε > 0, there exists a Cp-smooth Lipschitz function F : X → R such that |F (y)− f(y)| ≤ ε for every y ∈ Y ∩U . If we are given a separable subspace Y o...

We obtain two results concerning the Feichtinger conjecture for systems of normalized reproducing kernels in the model subspace KΘ = H 2 ⊖ ΘH of the Hardy space H, where Θ is an inner function. First, we verify the Feichtinger conjecture for the kernels k̃λn = kλn/‖kλn‖ under the assumption that sup n |Θ(λn)| < 1. Secondly, we prove the Feichtinger conjecture in the case where Θ is a one-compone...

We study the ordinary differential equation εẍ+ ẋ+ ε g(x) = εf(ωt), with f and g analytic and f quasi-periodic in t with frequency vector ω ∈ R. We show that if there exists c0 ∈ R such that g(c0) equals the average of f and the first non-zero derivative of g at c0 is of odd order n, then, for ε small enough and under very mild Diophantine conditions on ω, there exists a quasi-periodic solution...

Quasi extended Chebyshev spaces (QEC-spaces for short) represent the largest class of spaces of sufficient regularity which are suitable for design [1]. In particular, they contain the well-known extended Chebyshev spaces as a special instance (and therefore can represent transcendental functions) as well as the so called variable degree polynomial spaces [2], that are very effective in handlin...

In this paper we construct, using GAP System for Computational Discrete Algebra, some cyclic subspace codes, specially an optimal code over the finite field F210 . Further we present a definition and an example of the q-analogous of a m-quasi-cyclic subspace code over F28 .

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Forward transient electromagnetic modeling requires the numerical solution of a linear constant-coefficient initial-value problem for the quasi-static Maxwell equations. After discretization in space this problem reduces to a large system of ordinary differential equations, which is typically solved using finite-difference time-stepping. We compare standard time-stepping schemes such as the exp...