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1.
Dong Zhe 《Czechoslovak Mathematical Journal》2006,56(2):287-298
In this paper we investigate finite rank operators in the Jacobson radical
of Alg(
), where
are nests. Based on the concrete characterizations of rank one operators in Alg(
) and
, we obtain that each finite rank operator in
can be written as a finite sum of rank one operators in
and the weak closure of
equals Alg(
) if and only if at least one of
is continuous. 相似文献
2.
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
3.
Factorizations of One-Generated Composition Formations 总被引:2,自引:0,他引:2
A non-empty formation
of finite groups is said to be solubly saturated, or we call it a composition formation, if every finite group G having a normal subgroup N such that
belongs to
. An intersection of all composition formations containing a given group G is denoted cformG. Conditions are described under which
has the form
, where
. 相似文献
4.
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
5.
Andreas Rosenschon 《K-Theory》1999,16(2):185-199
Let X be a smooth projective variety over the complex numbers. We consider the cohomology of the sheaves
and
arising from Deligne–Beilinson cohomology and the Hodge filtration on the singular cohomology of X. We show that one can identify
with the image of the truncated regulator map c¯2,1. In particular, this implies that
is countable. Since this group is a direct summand of coker
, this gives a partial answer to Voisin's conjecture that cocker() is countable. In the case of X a surface, we prove that the Albanese kernel T(X) is isomorphic to the group of global sections of
if and only if pg=0. 相似文献
6.
The 3-local geometry
of the sporadic simple group Co1 has been known to have a cover
with a flag-transitive automorphism group which is a nonsplit extension of an elementary Abelian 2-group of rank 24 (the Leech lattice modulo 2) by Co1. It was conjectured that
was simply connected. We disprove this conjecture by constructing a double cover
of
. The automorphism group of
is of the shape
. However, it is not isomorphic to the involution centralizer of the Monster sporadic simple group. 相似文献
7.
Let ℂ denote the complex numbers and
denote the ring of complex-valued Laurent polynomial functions on ℂ\{0}. Furthermore, we denote by
the subsets of Laurent polynomials whose restriction to the unit circle is real, nonnegative, respectively. We prove that
for any two Laurent polynomials
, which have no common zeros in ℂ\{0} there exists a pair of Laurent polynomials
satisfying the equation Q
1
P
1 + Q
2
P
2 = 1. We provide some information about the minimal length Laurent polynomials Q
1 and Q
2 with these properties and describe an algorithm to compute them. We apply this result to design a conjugate quadrature filter
whose zeros contain an arbitrary finite subset Λ⊂ℂ\{0} with the property that for every
implies
and
.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
8.
Anderson D. D. Johnson E. W. Spellerberg II Richard L. 《Periodica Mathematica Hungarica》2002,44(1):111-126
Let L be an r-lattice, i.e., a modular multiplicative lattice that is compactly generated, principally generated, and has greatest element 1 compact. We consider certain subsets of L consisting of regular elements:
there is a compact element
with
there is a principal element
is a principal element with (0:X_{\alpha })=0\} . The first three subsets L_{f}, L_{sr}, and L_{r} are augmented filters
on L, i.e.,
is a multiplicatively closed subset of $L$ with $A\in
and $B\geq A$ with $B\in L$ implies $B\in
and hence are sublattices of $L$ closed under multiplication. We first consider the more general situation of augmented filters on $L.$ These results are then applied to study the four previously defined subsets for $L$ an $r$-lattice or Noether lattice (i.e., an $r$-lattice with ACC). Finally, we give a brief discussion of how the results for augmented lattices can be applied to subsets of $L$ which are regular with respect to an $L$-module. 相似文献
9.
Stefan Gille 《Archiv der Mathematik》2007,88(4):333-343
Let
be a closed subscheme of the noetherian scheme X. We show that if X has a dualizing complex
then there exists a dualizing complex
of Z such that there is an isomorphism of coherent Witt groups
for all
.
Received: 3 March 2006 相似文献
10.
Let
be a computable structure and let R be an additional relation on its domain. We establish a necessary and sufficient condition for the existence of an isomorphic copy
of
such that the image of R
is h-simple (h-immune) relative to
. 相似文献
11.
In this paper, we consider equations of the form
, where
is a function with values in the Hilbert space
, the operator B is symmetric, and the operator A is uniformly positive and self-adjoint in
. The linear operator
generating the C
0-semigroup in the energy space
is associated with this equation. We prove that this semigroup is exponentially stable if the operator B is uniformly positive and the operator A dominates B in the sense of quadratic forms. 相似文献
12.
Suppose that
,
, and
are three discrete probability distributions related by the equation (E):
, where
denotes the k-fold convolution of
In this paper, we investigate the relation between the asymptotic behaviors of
and
. It turns out that, for wide classes of sequences
and
, relation (E) implies that
, where
is the mean of
. The main object of this paper is to discuss the rate of convergence in this result. In our main results, we obtain O-estimates and exact asymptotic estimates for the difference
. 相似文献
13.
We define the reduced minimum modulus
of a nonzero element a in a unital C
*-algebra
by
. We prove that
. Applying this result to
and its closed two side ideal
, we get that dist
,
and
for any
if RR
= 0, where
and
is the quotient homomorphism and
. These results generalize corresponding results in Hilbert spaces. 相似文献
14.
We compute in this paper the distribution of the area
swept under the occupation process of an M/M/1 queue during a busy period. For this purpose, we use the expression of the Laplace transform
of the random variable
established in earlier studies as a fraction of Bessel functions. To get information on the poles and the residues of
, we take benefit of the fact that this function can be represented by a continued fraction. We then show that this continued
fraction is the even part of an S fraction and we identify its successive denominators by means of Lommel polynomials. This allows us to numerically evaluate
the poles and the residues. Numerical evidence shows that the poles are very close to the numbers
as
. This motivated us to formulate some conjectures, which lead to the derivation of the asymptotic behaviour of the poles and
the residues. This is finally used to derive the asymptotic behaviour of the probability survivor function
. The outstanding property of the random variable
is that the poles accumulate at 0 and its tail does not exhibit a nice exponential decay but a decay of the form
for some positive constants c and
, which indicates that the random variable
has a Weibull-like tail.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
15.
We consider a Skorohod map
which takes paths in
to paths which stay in the positive orthant
. We let
be the domain of definition of
. A convex and lower semi-continuous function
and a set
are given. We are concerned with the calculation of the infimum of the value
for t ⩾ 0 and absolutely continuous
subject to the conditions
and
. We show that such minimization problems characterize large deviation asymptotics of tail probabilities of the steady-state
distribution of certain reflected processes. We approximate the infimum by a sequence of finite-dimensional minimization problems.
This approximation allows to formulate an algorithm for the calculation of the infimum and to derive analytical bounds for
its value. Several applications are discussed including large deviations of generalized processor sharing and large deviations
of heavily loaded queueing networks.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
16.
N. Guillotin-Plantard 《Journal of Theoretical Probability》2001,14(1):241-260
In this paper, we study a
d
-random walk
on nearest neighbours with transition probabilities generated by a dynamical system
. We prove, at first, that under some hypotheses,
verifies a local limit theorem. Then, we study these walks in a random scenery
, a sequence of independent, identically distributed and centred random variables and show that for certain dynamic random walks,
satisfies a strong law of large numbers. 相似文献
17.
Amol Sasane 《Complex Analysis and Operator Theory》2009,3(1):323-330
Let E be a separable infinite-dimensional Hilbert space, and let denote the algebra of all functions that are holomorphic. If is a subalgebra of , then using an algebraic result of Corach and Larotonda, we derive that under some conditions, the Bass stable rank of is infinite. In particular, we deduce that the Bass (and hence topological stable ranks) of the Hardy algebra , the disk algebra and the Wiener algebra are all infinite.
Submitted: October 10, 2007., Revised: January 11, 2008., Accepted: January 12, 2007. 相似文献
18.
We construct a determinantal resolution of singularities for the universal subscheme in
and prove that it is isomorphic to the variety of total pairs
. 相似文献
19.
David A. Richter 《Acta Appl Math》2001,66(1):41-65
Starting from the commutation relations in a complex semisimple Lie algebra
, one may obtain a space
of vector fields on Euclidean space such that
and
are isomorphic when
is equipped with the usual Lie bracket between vector fields and the isotropy subalgebra of
is a Borel subalgebra
. Furthermore, one may adjoin to the vector fields in
multiplication operators to obtain an
-parameter family of distinct presentations of
as spaces of differential operators, where
is the dual of a Cartan subalgebra. Some of these presentations will preserve a space of polynomials on Euclidean space, and, in fact, all the finite-dimensional representations of
can be presented in this way. All of this is carried out explicitly for arbitrary
. In doing so, one discovers there is a Lie group of diffeomorphisms of the unipotent subgroup N complementary to B which acts on these presentations and preserves a certain notion of weight. 相似文献
20.
It is proved that if a normal semifinite weight on a von Neumann algebra
satisfies the inequality
for any selfadjoint operators
in
, then this weight is a trace. Several similar characterizations of traces among the normal semifinite weights are proved. In particular, Gardner's result on the characterization of traces by the inequality
is refined and reinforced. 相似文献