共查询到20条相似文献,搜索用时 93 毫秒
1.
Let be the set of nonnegative integers and the ring of integers. Let
be the ring of N × N matrices over generated by the following two matrices: one obtained from the identity matrix by shifting the ones one position to the right and the other one position down. This ring plays an important role in the study of directly finite rings. Calculation of invertible and idempotent elements of
yields that the subrings generated by them coincide. This subring is the sum of the ideal
consisting of all matrices in
with only a finite number of nonzero entries and the subring of
generated by the identity matrix. Regular elements are also described. We characterize all ideals of
, show that all ideals are finitely generated and that not all ideals of
are principal. Some general ring theoretic properties of
are also established. 相似文献
2.
Let
be realhomogeneous functions in
ofdegree
and let bethe Borel measure on
given by
where dx denotes theLebesgue measure on
and > 0. Let T
be the convolution operator
and let
Assume that, for x 0, the followingtwo conditions hold:
vanishes only at h = 0 and
. In this paper we show that if
then E
is the empty set and if
then E
is the closed segment withendpoints
and
. Also, we give some examples. 相似文献
3.
Salah Mecheri 《Czechoslovak Mathematical Journal》1999,49(4):843-847
In this paper we obtain some results concerning the set
, where
is the closure in the norm topology of the range of the inner derivation
A
defined by
A
(X) = AX – XA. Here
stands for a Hilbert space and we prove that every compact operator in
is quasinilpotent if A is dominant, where
is the closure of the range of
A
in the weak topology. 相似文献
4.
Ján Jakubík 《Czechoslovak Mathematical Journal》2003,53(3):641-653
In this paper we deal with the (, )-distributivity of an MV-algebra
, where and are nonzero cardinals. It is proved that if
is singular and (, 2)-distributive, then it is (, )-distributive. We show that if
is complete then it can be represented as a direct product of MV-algebras which are homogeneous with respect to higher degrees of distributivity. 相似文献
5.
Ján Jakubík 《Czechoslovak Mathematical Journal》2002,52(3):651-663
Let Int
be the lattice of all intervals of an MV-algebra
. In the present paper we investigate the relations between direct product decompositions of
and (i) the lattice Int
, or (ii) 2-periodic isometries on
, respectively. 相似文献
6.
F. G. Abdullayev 《Czechoslovak Mathematical Journal》2001,51(3):643-660
Let C be the extended complex plane; G C a finite Jordan with 0 G; w= (z) the conformal mapping of G onto the disk
normalized by
. Let us set
, and let
be the generalized Bieberbach polynomial of degree n for the pair (G,0), which minimizes the integral
in the class of all polynomials of degree not exceeding n with
. In this paper we study the uniform convergence of the generalized Bieberbach polynomials
with interior and exterior zero angles and determine its dependence on the properties of boundary arcs and the degree of their tangency. 相似文献
7.
Donal O'Regan 《Czechoslovak Mathematical Journal》1998,48(2):269-289
Existence results are established for the resonant problem y + m
a y = f(t, y) a.e. on [0, 1] with y satisfying Dirichlet boundary conditions. The problem is singular since f is a Carathéodory function,
with a > 0 a.e. on [0, 1] and
相似文献
8.
Adem Kilicman 《Czechoslovak Mathematical Journal》2001,51(3):463-471
Let
,
be ultradistributions in
and let
and
where
is a sequence in
which converges to the Dirac-delta function
. Then the neutrix product
is defined on the space of ultradistributions
as the neutrix limit of the sequence
provided the limit
exist in the sense that
for all in
. We also prove that the neutrix convolution product
exist in
, if and only if the neutrix product
exist in
and the exchange formula
is then satisfied. 相似文献
9.
Václav Tryhuk 《Czechoslovak Mathematical Journal》2000,50(3):509-518
The paper describes the general form of an ordinary differential equation of the order n + 1 (n 1) which allows a nontrivial global transformation consisting of the change of the independent variable. A result given by J. Aczél is generalized. A functional equation of the form
where
are given functions,
is solved on
. 相似文献
10.
In this paper we define a lattice order on a set F of binary functions. We then provide necessary and sufficient conditions for the resulting algebra
F to be a distributive lattice or a Boolean algebra. We also prove a Cayley theorem for distributive lattices by showing that for every distributive lattice
, there is an algebra
F of binary functions, such that
is isomorphic to
F and we show that
F is a distributive lattice iff the operations and are idempotent and cummutative, showing that this result cannot be generalized to non-distributive lattices or quasilattices without changing the definitions of and . We also examine the equational properties of an Algebra
for which
, now defined on the set of binary
-polynomials is a lattice or Boolean algebra. 相似文献
11.
12.
S. R. Grace 《Czechoslovak Mathematical Journal》1999,49(1):45-52
Sufficient conditions are presented for all bounded solutions of the linear system of delay differential equations
to be oscillatory, where q
ij(–, ), h
jj (0, ), i, j = 1,2,..., n. Also, we study the oscillatory behavior of all bounded solutions of the linear system of neutral differential equations
where c, g and h are real constants and i = 1,2,..., n. 相似文献
13.
Let H1(
) be the usual Hardy space on
. We show that the couple (H1(
), L(
) is a Calderón couple. This result immediately follows from the following stronger one: Given any fH1(
) +L(
) there exist two linear operators U and V satisfying the properties: (i) Uf=Nf (Nf being the non-tangential maximal function of f) and U is contractive from H1(
) to L1(
) and also from L(
) to L(
); (ii) V(Nf)=f, V is similtaneously bounded from L1(
) to H1(
) and from L(
) to L(
) and the norms of V on these spaces are controlled by a universal constant. We also have similar results on the couple (Lp(
), BMO (
)) for every 1
相似文献
14.
Zdzislaw Brzezniak Szymon Peszat Jerzy Zabczyk 《Czechoslovak Mathematical Journal》2001,51(4):679-684
Let B be a Brownian motion, and let
be the space of all continuous periodic functions f with period 1. It is shown that the set of all f
such that the stochastic convolution
does not have a modification with bounded trajectories, and consequently does not have a continuous modification, is of the second Baire category. 相似文献
15.
B. Yousefi 《Czechoslovak Mathematical Journal》2004,54(1):261-266
Let
be a sequence of positive numbers and 1 p< . We consider the space H
p() of all power series
such that
. We investigate strict cyclicity of
the weakly closed algebra generated by the operator of multiplication by zacting on H
p(), and determine the maximal ideal space, the dual space and the reflexivity of the algebra
. We also give a necessary condition for a composition operator to be bounded on H
p() when
is strictly cyclic. 相似文献
16.
G. Kuba 《Acta Mathematica Hungarica》2001,91(4):325-332
For a large real parameter t and 0 a b
we consider sums
where is the rounding error function, i.e. (z) = z - [z] - 1/2. We generalize Huxley's well known estimate
by showing that
holds uniformly in 0 a b
. Fruther, we investigate an analogous question related to the divisor problem and show that the inequality
, which (due to Huxley) holds uniformly in 0 a b
, and which is in general not true for 1 a b t, is true uniformly in 0 a b
. 相似文献
17.
In this paper, we suggest a new functional approach to the study of group classes which enables us to describe all formations and Fitting classes of finite groups in the language of functions. The notions of
-fibered formation and of
-fibered Fitting class with direction are introduced. A direction is defined as a mapping of the set
of all primes into the set of all nonempty Fitting formations. The existence of infinitely many mappings of this kind makes it possible to construct new forms of formations and Fitting classes for a given nonempty set
. In particular, an
-local formation is an
-fibered formation with a direction such that
for any prime p. In the paper we study some basic properties of
-fibered formations and of
-fibered Fitting classes with direction and obtain the structure of their minimal satellites for a given . 相似文献
18.
Let G be the group "ax + b" of affine transformations of the line and let U be a neighbourhood of 1 in G. It is proved that there is another neighborhood V of 1 such that to each finite sequence g1,...,gn V there corresponds a sequence of signs 1,...,n = ±1 with
U for k = 1,...,n. This implies that G satisfies the following analogue of the Dvoretzky-Hanani theorem: to each sequence
converging to 1 in G there corresponds a sequence of signs k = ±1 such that the infinite product
is convergent. 相似文献
19.
Damjan Kobal 《K-Theory》1999,17(2):113-140
The goal of this paper is to present a new view on the link between the well known K-theory of finitely generated projective modules and much less understood K-theory of Hermitian forms on finitely generated projective modules.For a given Hermitian ring (R, , ), we obtain the K-theory space KR equipped with an involution and the Hermitian K-theory space KHerm(R, , ). The fixed subspace
2 is homotopy equivalent to the Hermitian K-theory space KHerm(R,, , ). We construct the Karoubi Tower diagram, which is obtained by iterating Karoubi's construction of the homotopy fibers of the forgetful and hyperbolic maps. Using an interesting factorization of these maps, we prove various homotopy properties of the Karoubi Tower. The homotopy inverse limit of the Karoubi Tower is homotopy equivalent to the homotopy fibre of the inclusion of the fixed set
2 into the homotopy fixed set
h
2. Considering Karoubi's fundamental periodicity theorem, the Karoubi Tower generalizes the low dimensional connections between Hermitian K-theory and K-theory groups. Illustrative examples of the Karoubi Tower are given by the finite field case and the classical Hermitian rings over
,
and
. Considering topological K-theory for these cases, the Karoubi Tower comprises the classical Bott periodicity.Another important application of the Karoubi Tower is an elegant and comprehensive generalization of the classical invariants of quadratic forms. 相似文献
20.
Yuanji Cheng 《Czechoslovak Mathematical Journal》1997,47(4):681-687
In this paper, we consider the existence and nonexistence of positive solutions of degenerate elliptic systems
where –p is the p-Laplace operator, p > 1 and is a C
1,-domain in
. We prove an analogue of [7, 16] for the eigenvalue problem with
and obtain a non-existence result of positive solutions for the general systems. 相似文献