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1.
Let
be a hereditary torsion theory for the category
-mod of unital left
-modules over an associative ring
with an identity element. The purpose of this note is to prove that if the associated Gabriel filter
consists of finitely presented left ideals, then every module has a
-injective cover and if
contains a cofinal subset of finitely presented left ideals, then every module has a
-torsionfree
-injective cover. The methods used working with pure submodules contained in ``large" submodules also allow to unify the proofs of some previously known results. 相似文献
2.
Daniel Berend Michael D. Boshernitzan Grigori Kolesnik 《Acta Mathematica Hungarica》2002,95(1-2):1-20
For some oscillating functions, such as
, we consider the distribution properties modulo 1 (density, uniform distribution) of the sequence
,
. We obtain positive and negative results covering the case when the factor
is replaced by an arbitrary function
of at most polynomial growth belonging to any Hardy field. (The latter condition may be viewed as a regularity growth condition on
.) Similar results are obtained for the subsequence
, taken over the primes
相似文献
3.
For
denote by
a polynomial of best weighted
-approximation to
on
of degree
. In the present paper, we are dealing with the asymptotic distribution of sign changes of the error functions
. 相似文献
4.
This paper considers the approximation of the Kantorovich–Shepard operators in
spaces for
. For
the Kantorovich–Shepard operators
are defined by (1.1). Then
where
is a positive number depending only on
and , and $$ \varepsilon_{n} =\cases{ n^{-1}, & if \
2$$
" align="middle" border="0">
; \cr\nosm n^{-1}\log n, & if \
; \cr\nosm n^{1-\lambda}, & if \
. \cr} $$ 相似文献
5.
Adjoint Clifford Rings 总被引:1,自引:0,他引:1
Let
> be a ring and define
, which yields a monoid
, called the {\it adjoint semigroup\/} or {\it circle semigroup\/} of
. This paper continues the authors" investigations into the relationship between a ring and its adjoint semigroup, focusing here on the case where
is a Clifford semigroup. Such rings are called {\it adjoint Clifford rings.\/} Structure theory for such rings is developed and examples are given to illustrate and delimit the theory. 相似文献
6.
Gerald Kuba 《Acta Mathematica Hungarica》2002,95(1-2):115-124
For a positive real parameter t, real numbers , , and
, we consider sums
, where
is the rounding error function, i.e.\
. Generalizing and improving the main result of Part I of the paper we show that there exists an absolute constant
such that
for all
, and all
. Further, we give applications concerning the circle problem with linear, polynomial, and general weight. 相似文献
7.
Two results on composed functions
are proven. First we give conditions on
and
so that the mean
behaves like
, if
, including the examples
1$$
" align="middle" border="0">
,
not an integer for
. Secondly we find conditions on the real positive numbers
, such that
are almost periodic and we compute their mean values and spectra. 相似文献
8.
It is known that the ring
of all Baire functions carrying the pointwise convergence yields a sequential completion of the ring
of all continuous functions. We investigate various sequential convergences related to the pointwise convergence and the process of completion of
. In particular, we prove that the pointwise convergence fails to be strict and prove the existence of the categorical ring completion of
which differs from
. 相似文献
9.
Ferenc Weisz 《Acta Mathematica Hungarica》2002,96(1-2):149-160
A general summability method of two-dimensional Fourier transforms is given with the help of an integrable function
. Under some conditions on
we show that the maximal operator of the Marcinkiewicz-
-means of a tempered distribution is bounded from
to
for all
and, consequently, is of weak type
, where
depends only on
. As a consequence we obtain a generalization for Fourier transforms of a summability result due to Marcinkievicz and Zhizhiashvili,
more exactly, the Marcinkiewicz-
-means of a function
converge a.e. to the function in question. Moreover, we prove that the Marcinkiewicz-
-means are uniformly bounded on the spaces
and so they converge in norm
. Some special cases of the Marcinkievicz-
-summation are considered, such as the Weierstrass, Picar, Bessel, Fejér, de la Vallée-Poussin, Rogosinski and Riesz summations.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
10.
11.
Let
and
be Hausdorff topological vector spaces over the field
, let
be a bilinear functional, and let
be a non-empty subset of
. Given a set-valued map
and two set-valued maps
, the generalized bi-quasi-variational inequality (GBQVI) problem is to find a point
and a point
such that
and
for all
and for all
or to find a point
a point
and a point
such that
and
for all
. The generalized bi-quasi-variational inequality was introduced first by Shih and Tan [8] in 1989. In this paper we shall obtain some existence theorems of generalized bi-quasi-variational inequalities as application of upper hemi-continuous operators [4] in locally convex topological vector spaces on compact sets. 相似文献
12.
Hiroshi Suzuki 《Journal of Algebraic Combinatorics》1998,7(2):165-180
It is well known that imprimitive P-polynomial association schemes
with
are either bipartite or antipodal, i.e., intersection numbers satisfy either
for all
for all
. In this paper, we show that imprimitive
-polynomial association schemes
with
are either dual bipartite or dual antipodal, i.e., dual intersection numbers satisfy either
. 相似文献
13.
A theorem of Ferenc Lukács states that if a periodic function
is integrable in Lebesgue"s sense and has a discontinuity of first kind at some point
, then the
th partial sum of the conjugate series to its trigonometric Fourier series at
divided by
converges to
as
. An analogue of this theorem for Walsh–Fourier series was proved by Rafat Riad. The main aim of the present paper is to extend the latter result from single to double Wals–Fourier series. We consider also functions of two variables which are of bounded variation over a rectangle in the sense of Hardy and Krause. Among others, we present a proof of the existence of the so-called sector limits of such functions at each point. 相似文献
14.
A. Cossidente J. W. P. Hirschfeld G. Korchmáros F. Torres 《Compositio Mathematica》2000,121(2):163-181
The number N of rational points on an algebraic curve of genus g over a finite field
satisfies the Hasse–Weil bound
. A curve that attains this bound is called maximal. With
and
, it is known that maximalcurves have
. Maximal curves with
have been characterized up to isomorphism. A natural genus to be studied is
and for this genus there are two non-isomorphic maximal curves known when
. Here, a maximal curve with genus g
2 and a non-singular plane model is characterized as a Fermat curve of degree
. 相似文献
15.
The following assertion is proved. Let
be the set of integers the number of the prime power of which is
. Let
be the size of
. Then for each irrational
, uniformly in
, \begin{equation*} \frac{1}{\pi_k(x)} \bigg|\sum _{\alul{n\le x}{n\in\cN_k}} f(n) e^{2\pi in\alpha}\bigg|\to 0, \end{equation*}
where
is an arbitrary multiplicative function with
,
is a positive constant.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
16.
Á Császár 《Acta Mathematica Hungarica》2002,95(1-2):83-99
We study properties of the operation
, defined for structures corresponding to different subcategories of MER, as merotopies, filter merotopies, contiguities,
-contiguities and closures. In particular, we examine commutativity of
and the operation according to which a structure induces a structure of another type (as e.g.\ a merotopy induces a closure) and the inverse operations of the former. 相似文献
17.
The Hoff equation
describes the H-beam buckling dynamics. We show that the phase space of the Hoff equation is a simple
Banach manifold modeled on a subspace complementary to the kernel
. 相似文献
18.
O. V. Sarafanov 《Journal of Mathematical Sciences》2004,120(2):1195-1239
The C
*-algebra
generated by the operators of pseudodifferential boundary value problems on a manifold
with smooth closed disjoint edges and boundary
is studied. The operators act in the space L
2(
)
L
2(
). The goal of this paper is to describe all (up to an equivalence) irreducible representations of the algebra
Bibliography: 12 titles. 相似文献
19.
Using an analog of the classical Frobenius recursion, we define the notion of a Frobenius
-homomorphism. For
, this is an ordinary ring homomorphism. We give a constructive proof of the following theorem. Let X be a compact Hausdorff space,
the
th symmetric power of X, and
the algebra of continuous complex-valued functions on X with the sup-norm; then the evaluation map
defined by the formula
identifies the space
with the space of all Frobenius
-homomorphisms of the algebra
into
with the weak topology. 相似文献
20.
We construct the trajectory attractor
of a three-dimensional Navier--Stokes system with exciting force
. The set
consists of a class of solutions to this system which are bounded in
, defined on the positive semi-infinite interval
of the time axis, and can be extended to the entire time axis
so that they still remain bounded-in-
solutions of the Navier--Stokes system. In this case any family of bounded-in-
solutions of this system comes arbitrary close to the trajectory attractor
. We prove that the solutions
are continuous in t if they are treated in the space of functions ranging in
. The restriction of the trajectory attractor
to
,
, is called the global attractor of the Navier--Stokes system. We prove that the global attractor
thus defined possesses properties typical of well-known global attractors of evolution equations. We also prove that as
the trajectory attractors
and the global attractors
of the
-order Galerkin approximations of the Navier--Stokes system converge to the trajectory and global attractors
and
, respectively. Similar problems are studied for the cases of an exciting force of the form
depending on time
and of an external force
rapidly oscillating with respect to the spatial variables or with respect to time
. 相似文献