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1.
For suitable positive integers n and k let m(n, k) denote the maximum number of edges in a graph of order n which has a unique k-factor. In 1964, Hetyei and in 1984, Hendry proved
for even n and
, respectively. Recently, Johann confirmed the following conjectures of Hendry:
for
and kn even and
for n = 2kq, where q is a positive integer. In this paper we prove
for
and kn even, and we determine m(n, 3). 相似文献
2.
Let X be a Banach space and let
A be a closed linear operator on
X. It is shown that the abstract Cauchy problem
enjoys maximal regularity in weighted
L
p
-spaces with weights
, where
,
if and only if it has the property of maximal
L
p
-regularity.
Moreover, it is also shown that the derivation operator
admits an
-calculus in weighted
L
p
-spaces.
Received: 26 February 2003 相似文献
3.
Given
, a compact abelian group G and a function
, we identify the maximal (i.e. optimal) domain of the convolution
operator
(as an operator from Lp(G) to itself). This is the
largest Banach function space (with order continuous norm) into which Lp(G)
is embedded and to which
has a continuous extension, still with values
in Lp(G). Of course, the optimal domain depends on p and g. Whereas
is compact, this is not always so for the extension of
to its optimal domain.
Several characterizations of precisely when this is the case are presented. 相似文献
4.
We prove the estimate
for the number Ek(N)
of k-tuples
(n + a1,..., n + ak) of primes not exceeding N,
for k of size c1 log N and
N sufficiently large.
A bound of this strength was previously known in the special case
<
only, (Vaughan, 1973). For general ai this is an improvement upon the work of
Hofmann and Wolke (1996).
The number of prime tuples of this size has
considerable oscillations, when varying the prime pattern.
Received: 20 December 2002 相似文献
5.
In this paper we show that if X is an s-distance set in
m
and X is on
p concentric spheres then
Moreover if
X is antipodal, then
. 相似文献
6.
T. Simon 《Journal of Theoretical Probability》2004,17(4):979-1002
Let Z
t
, t 0 be a strictly stable process on
with index (0, 2]. We prove that for every p > , there exists = , p
and
such that
where || Z||
p
stands for the strong p-variation of Z on [0,1]. The critical exponent p
, takes a different shape according as | Z| is a subordinator and p > 1, or not. The small ball constant
is explicitly computed when p > 1, and a lower bound on
is easily obtained in the general case. In the symmetric case and when p > 2, we can also give an upper bound on
in terms of the Brownian small ball constant under the (1/p)-Höder semi-norm. Along the way, we remark that the positive random variable
is not necessarily stable when p > 1, which gives a negative answer to an old question of P. E. Greenwood.10 相似文献
7.
Let H be an atomic monoid. For let denote the set of all with the following property: There exist atoms (irreducible elements) u
1, …, u
k
, v
1, …, v
m
∈ H with u
1· … · u
k
= v
1 · … · v
m
. We show that for a large class of noetherian domains satisfying some natural finiteness conditions, the sets are almost arithmetical progressions. Suppose that H is a Krull monoid with finite cyclic class group G such that every class contains a prime (this includes the multiplicative monoids of rings of integers of algebraic number
fields). We show that, for every , max which settles Problem 38 in [4].
Authors’ addresses: W. Gao, Center for Combinatorics, Nankai University, Tianjin 300071, P.R. China; A. Geroldinger, Institut
für Mathematik und Wissenschaftliches Rechnen, Karl-Franzens-Universit?t Graz, Heinrichstra?e 36, 8010 Graz, Austria 相似文献
8.
In this paper we prove that if
is a set of
k positive integers and
{A
1,
..., A
m
} is a family of subsets
of an n-element set
satisfying
, for all 1
i <
j m, then
. The case
k = 1 was proven 50 years ago
by Majumdar. 相似文献
9.
Let p be a prime number.
Let G be a finite
p-group and
. Denote by
the complex conjugate of
. Assume that
. We show that the number of
distinct irreducible constituents of the product
is at least
.
Received: 17 March 2003 相似文献
10.
V. N. Konovalov 《Ukrainian Mathematical Journal》2004,56(7):1074-1101
Let s 0 and let
+
s
be the set of functions x defined on a finite interval I and such that, for all collections of s
+ 1 pairwise different points t
0,..., t
s
I, the corresponding divided differences [x; t
0,...,t
s
] of order s are nonnegative. Let
+
s
B
p
+
s
B
p, 1 p where B
p is a unit ball in the space L
p, and let
+
s
L
q
+
s
L
q, 1 q . For every s 3 and 1 q p , we determine the exact orders of the shape-preserving Kolmogorov widths {x - y} \right\ L_q , $$]]> , where M
n is the collection of all affine linear manifolds M
n in L
q such that dim M
n n and M
n
+
s
L
q .Translated from Ukrainskyi Matematychnyi Zhurnal, Vol. 56, No. 7, pp. 901–926, July, 2004. 相似文献
11.
The N-commutator
is conjecturally a well-defined nontrivial operation on
for x =
(x
1, ... ,
x
n
)
if and only if N =
n
2 +
2n - 2. This is
proved for n = 2 and confirmed by
computer experiments for n < 5.
Under 2- and 5-commutators the algebra of divergence-free
vector fields in two dimensions is an sh-Lie (strong homotopic
Lie) algebra in the sense of Stasheff. Similarly,
W(2) is an
sh-Lie algebra with respect to 2- and 6-commutators. 相似文献
12.
Vladimir V. Tkachuk 《Acta Mathematica Hungarica》2005,107(4):253-265
Summary We prove that, for any Tychonoff X, the space Cp(X) is K-analytic if and only if it has a compact cover {Kp: p } such that Kp subset Kq whenever p,q and p q. Applying this result we show that if Cp(X) is K-analytic then Cp(X) is K-analytic as well. We also establish that a space Cp(X) is K-analytic and Baire if and only if X is countable and discrete. 相似文献
13.
Let A be a compact set in of Hausdorff dimension d. For s ∈ (0,d) the Riesz s-equilibrium measure μ
s
is the unique Borel probability measure with support in A that minimizes
over all such probability measures. If A is strongly -rectifiable, then μ
s
converges in the weak-star topology to normalized d-dimensional Hausdorff measure restricted to A as s approaches d from below.
This research was supported, in part, by the U. S. National Science Foundation under grants DMS-0505756 and DMS-0808093. 相似文献
14.
A subgroup H of a finite group G is said to be c*-supplemented in G if there exists a subgroup K such that G = HK and H ⋂ K is permutable in G. It is proved that a finite group G that is S
4-free is p-nilpotent if N
G
(P) is p-nilpotent and, for all x ∈ G\N
G
(P), every minimal subgroup of
is c*-supplemented in P and (if p = 2) one of the following conditions is satisfied: (a) every cyclic subgroup of
of order 4 is c*-supplemented in P, (b)
, (c) P is quaternion-free, where P a Sylow p-subgroup of G and
is the p-nilpotent residual of G. This extends and improves some known results.
Published in Ukrains’kyi Matematychnyi Zhurnal, Vol. 59, No. 8, pp. 1011–1019, August, 2007. 相似文献
15.
The so-called Kelly conjecture states that every regular tournament on 2k+1 vertices has a decomposition into k-arc-disjoint hamiltonian cycles. In this paper we formulate a generalization of that conjecture, namely we conjecture that every k-arc-strong tournament contains k arc-disjoint spanning strong subdigraphs. We prove several results which support the conjecture:If D = (V, A) is a 2-arc-strong semicomplete digraph then it contains 2 arc-disjoint spanning strong subdigraphs except for one digraph on 4 vertices.Every tournament which has a non-trivial cut (both sides containing at least 2 vertices) with precisely k arcs in one direction contains k arc-disjoint spanning strong subdigraphs. In fact this result holds even for semicomplete digraphs with one exception on 4 vertices.Every k-arc-strong tournament with minimum in- and out-degree at least 37k contains k arc-disjoint spanning subdigraphs H
1, H
2, . . . , H
k
such that each H
i
is strongly connected.The last result implies that if T is a 74k-arc-strong tournament with speci.ed not necessarily distinct vertices u
1, u
2, . . . , u
k
, v
1, v
2, . . . , v
k
then T contains 2k arc-disjoint branchings
where
is an in-branching rooted at the vertex u
i
and
is an out-branching rooted at the vertex v
i
, i=1,2, . . . , k. This solves a conjecture of Bang-Jensen and Gutin [3].We also discuss related problems and conjectures.
相似文献
Anders YeoEmail: |
16.
We consider k-th power of upper bound graphs. According
to the characterization of upper bound graphs, we obtain a characterization of
k-th power of upper bound graphs. That is,
for a connected upper bound graph
G, Gk is an upper bound graph if
and only if for any pair of
Ak
-simplicial vertices s1,
s2 such that
, there exists a
Gk
-simplicial vertex s satisfying
the conditions:
and
. Furthermore we also get some properties on squares of upper bound graphs.AMS Subject Classification: 05C62. 相似文献
17.
It is proved that a lacunary sequence of the Ciesielski-Fourier series of
converges almost everywhere to f.
Received: 8 September 2003 相似文献
18.
Let p be a prime,
a finite p-group,
any finite group with order divisible by p,
and
any action of
on
. We show that the cardinality of the set of all derivations
with respect to this action is a multiple of
p. This
generalises theorems of Frobenius and Hall.
Received: 16 June 2003 相似文献
19.
In this paper we construct certain moduli spaces, which we call
moduli spaces of (principal) F-bundles,
and study their basic properties. These spaces are
associated to triples consisting of a smooth projective geometrically
connected curve over a finite field, a split
reductive group G, and an irreducible
algebraic representation
.of
of
Our spaces generalize moduli
spaces of F-sheaves, studied
by Drinfeld and Lafforgue, which correspond to the case G
= GLr
and
is the tensor product of the standard
representation and its dual. The importance of the moduli spaces
of F-bundles is due to the
belief that Langlands correspondence is realized in their cohomology. 相似文献
20.
Let C be a set of objects in a triangulated compactly generated category
We denote by
the smallest suspended subcategory closed under coproducts which contains C (the smallest cosuspended subcategory closed under products which contains
C). We prove that if C is a set of compacts objects then
is a t-structure in
where TC
I is the dual of C with respect to an injective cogenerator
I in the category Mod
C. Moreover, we show that:
C is a tilting set if and only if
And, this is equivalent to TCI is a cotilting object in
Received: 28 March 2003 相似文献