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1.
This paper studies the cardinality of a smallest set
of t-subspaces of the finite projective spaces PG(n, q) such that every s-subspace is incident with at least one element of
, where 0 t < s n. This is a very difficult problem and the solution is known only for very few families of triples (s, t, n). When the answer is known, the corresponding blocking configurations usually are partitions of a subspace of PG(n, q) by subspaces of dimension t. One of the exceptions is the solution in the case t = 1 and n = 2s. In this paper, we solve the case when t = 1 and 2s < n 3s-3 and q is sufficiently large. 相似文献
2.
Shuguan Ji 《Calculus of Variations and Partial Differential Equations》2008,32(2):137-153
In this paper, we study the problem of time periodic solutions to the nonlinear wave equation with x-dependent coefficients on under the boundary conditions a
1
y(0, t)+b
1
y
x
(0, t) = 0, ( for i = 1, 2) and the periodic conditions y(x, t + T) = y(x, t), y
t
(x, t + T) = y
t
(x, t). Such a model arises from the forced vibrations of a bounded nonhomogeneous string and the propagation of seismic waves
in nonisotropic media. For , we establish the existence of time periodic solutions in the weak sense by utilizing some important properties of the wave
operator with x-dependent coefficients.
This work was supported by the 985 Project of Jilin University, the Specialized Research Fund for the Doctoral Program of
Higher Education, and the Science Research Foundation for Excellent Young Teachers of College of Mathematics at Jilin University. 相似文献
3.
Charles J. Colbourn Dean G. Hoffman Kevin T. Phelps Vojtěch Rödl Peter M. Winkler 《Combinatorica》1991,11(3):207-218
We prove that the number oft-wise balanced designs of ordern is asymptotically
, provided that blocks of sizet are permitted. In the process, we prove that the number oft-profiles (multisets of block sizes) is bounded below by
and above by
for constants c2>c1>0. 相似文献
4.
The number of Fq
-rational points of a plane non-singular algebraic curve
defined over a finite field Fq
is computed, provided that the generic point of
is not an inflexion and that
is Frobenius non-classical with respect to conics.
Received: 18 March 2003 相似文献
5.
M. Wiessner 《Periodica Mathematica Hungarica》1993,26(3):205-210
Given
and a sequence of Dirichlet polynomials
estimates for the coefficientsa
n are proved if {n} is uniformly bounded on a region containing a half plane. Thereby a result is obtained which is an analogue of a known result for polynomials, that is for theA-transforms of the geometric sequence; moreover a Jentzsch type theorem for {n(z)} is derived. 相似文献
6.
In this article, we consider various arithmetic properties of the function
which denotes the number of overpartitions of n using only odd parts. This function has arisen in a number of recent papers, but in contexts which are very different from
overpartitions. We prove a number of arithmetic results including several Ramanujan-like congruences satisfied by
and some easily-stated characterizations of
modulo small powers of two. For example, it is proven that, for n ≥ 1,
(mod 4) if and only if n is neither a square nor twice a square.
Received March 17, 2005 相似文献
7.
We consider a question raised by Suhov and Voice from quantum information theory and quantum computing. An element of a partition
of {1, ..., n} is said to be block-stable for
if it is not moved to another block under the action of π. The problem concerns the determination of the generating series
for elements of
with respect to the number of block-stable elements of a canonical partition of a finite n-set, with block sizes k1, ..., kr, in terms of the moment (power) sums pq(k1, ..., kr). We also consider the limit
subject to the condition that
exists for q = 1, 2,....
Received January 31, 2006 相似文献
8.
Let be a smoothly bounded domain. Suppose Ω has a defining function, such that the sum of any q eigenvalues of its complex Hessian is non-negative. We show that this implies global regularity of the Bergman projection, B
j-1, and the -Neumann operator, N
j
, acting on (0,j)-forms, for .Research of the first author was partially supported by a Rackham Fellowship.Research of the second author was partially supported by an NSF grant. 相似文献
9.
Dirk Segers 《Mathematische Annalen》2006,336(3):659-669
Let K be a p-adic field, R the valuation ring of K, P the maximal ideal of R and q the cardinality of the residue field R/P. Let f be a polynomial over R in n >1 variables and let χ be a character of . Let M
i
(u) be the number of solutions of f = u in (R/P
i
)
n
for and. These numbers are related with Igusa’s p-adic zeta function Z
f,χ(s) of f. We explain the connection between the M
i
(u) and the smallest real part of a pole of Z
f,χ(s). We also prove that M
i
(u) is divisible by , where the corners indicate that we have to round up. This will imply our main result: Z
f,χ(s) has no poles with real part less than − n/2. We will also consider arbitrary K-analytic functions f. 相似文献
10.
A submeasure μ defined on the subsets of is nonatomic if for every ℓ ≥ 1 there exists a partition of into a finite number of parts on which μ is bounded from above by 1/ℓ. In this paper we answer several natural questions concerning nonatomic submeasures d
F
that are determined (like the standard density) by a family F of finite subsets of . We first show that if the number of n-element sets in F grows at most exponentially with n, then d
F
is nonatomic; but if this growth condition fails, then d
F
need not be nonatomic in general. We next prove that, for a nonatomic submeasure d
F
, the minimal number of sets in a 1/ℓ-small partition of can grow arbitrarily fast with ℓ. We also give a simple example of a nonatomic submeasure that is not equivalent to a submeasure of type d
F
.
The second author acknowledges a generous support of the Foundation for Polish Science. 相似文献
11.
Vasilii V. Kurta 《Archiv der Mathematik》2006,87(4):368-374
We generalize and improve recent non-existence results for global solutions to the Cauchy problem for the inequality
as well as for the equation ut = Δu + |u|q in the half-space
.
Received: 16 September 2005 相似文献
12.
We prove two results on mod p properties of Siegel modular forms. First, we use theta series in order to construct of a Siegel modular form of weight p−1 which is congruent to 1 mod p. Second, we define a theta operator on q-expansions and show that the algebra of Siegel modular forms mod p is stable under , by exploiting the relation between and generalized Rankin-Cohen brackets. 相似文献
13.
The main results of this paper are a generalization of the results of S. Fajtlowicz and J. Mycielski on convex linear forms.
We show that if Vn is the variety generated by all possible algebras
, where R denotes the real numbers and
, for some
, then any basis for the set of all identities satisfied by Vn is infinite. But on the other hand, the identities satisfied by Vn are a consequence of gL and μn, where μn is the n-ary medial law and the inference rule gL is an implication patterned after the classical rigidity lemma of algebraic geometry. We also prove that the identities satisfied
by
are a consequence of gL and μn iff {p1, ... , pn} is algebraically independent. We then prove analagous results for algebras
of arbitrary type τ and in the final section of this paper, we show that analagous results hold for Abelian group hyperidentities.
This paper is dedicated to Walter Taylor.
Received July 16, 2005; accepted in final form January 12, 2006.
The research of both authors was supported by an operating grant ODP0008215 from NSERC. 相似文献
14.
We study the boundary value problem in Ω, u = 0 on ∂Ω, where Ω is a bounded domain in with smooth boundary, λ is a positive real number, and the continuous functions p
1, p
2, and q satisfy 1 < p
2(x) < q(x) < p
1(x) < N and for any . The main result of this paper establishes the existence of two positive constants λ0 and λ1 with λ0 ≤ λ1 such that any is an eigenvalue, while any is not an eigenvalue of the above problem. 相似文献
15.
Summary. Let k ≥ 1 be any integer. Let G be a finite abelian group of exponent n. Let sk(G) be the smallest positive integer t such that every sequence S in G of length at least t has a zero-sum subsequence of length kn. We study this constant for groups
when d = 3 or 4. In particular, we prove, as a main result, that
for every k ≥ 4,
and
for every prime p ≥ 5. 相似文献
16.
Zhi-Wei Sun 《Combinatorica》2003,23(4):681-691
For a finite system
of arithmetic sequences
the covering function is w(x)
= |{1 s
k : x as (mod
ns)}|. Using equalities
involving roots of unity we characterize those systems with a
fixed covering function w(x). From the characterization we reveal
some connections between a period n0 of
w(x) and the moduli
n1, .
. . , nk in such a system
A. Here are three central
results: (a) For each r=0,1,
. . .,nk/(n0,nk)–1 there exists a
Jc{1, . . . ,
k–1} such that
. (b) If
n1
···nk–l <nk–l+1 =···=nk (0 <
l <
k), then for any positive
integer r <
nk/nk–l with
r 0 (mod
nk/(n0,nk)), the binomial
coefficient
can be written as the
sum of some (not necessarily distinct) prime divisors of
nk. (c)
max(xw(x)
can be written in the form
where
m1, .
. .,mk are positive
integers.The research is supported by the Teaching and
Research Award Fund for Outstanding Young Teachers in Higher
Education Institutions of MOE, and the National Natural Science
Foundation of P. R. China. 相似文献
17.
Walter Taylor 《Algebra Universalis》2006,55(4):409-456
A (finite or infinite) set ∑ of equations, in operation symbols Ft (t ∈T) and variables xi, is said to be compatible with
iff there exist continuous operations FtA on
such that the algebra
satisfies the equations ∑ (with the variables xi understood as universally quantified). It is proved that there is no algorithm to decide
-compatibility for all finite ∑.
If the definition is restricted to C1 idempotent operations FtA , then there does exist an algorithm for compatibility.
Received August 9, 2005; accepted in final form February 14, 2006. 相似文献
18.
Lydia Außenhofer 《Mathematische Zeitschrift》2007,257(2):239-250
For a topological group G, we denote by G
a
the arc component of the neutral element and by the character group of G, i.e. the group of all continuous homomorphisms from G into T. We prove the following theorem: Let G be a connected locally compact abelian group and let be the embedding. Then is a topological isomorphism. In particular, the character group of the arc component of a compact abelian group is discrete.
Some conclusions will be drawn. 相似文献
19.
We describe a decomposition of the polynomials f
n
:= f
n,B,a
defined by
where B and a are rational numbers. We also present an application to related Diophantine equations.
The authors were supported by the Ministry of Science, Education and Sports, Republic of Croatia, grant 0037110. 相似文献
20.
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