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1.
Given a finite subset
of an additive group
such as
or
, we are interested in efficient covering of
by translates of
, and efficient packing of translates of
in
. A set
provides a covering if the translates
with
cover
(i.e., their union is
), and the covering will be efficient if
has small density in
. On the other hand, a set
will provide a packing if the translated sets
with
are mutually disjoint, and the packing is efficient if
has large density.
In the present part (I) we will derive some facts on these concepts when
, and give estimates for the minimal covering densities and maximal packing densities of finite sets
. In part (II) we will again deal with
, and study the behaviour of such densities under linear transformations. In part (III) we will turn to
.
Authors’ address: Department of Mathematics, University of Colorado at Boulder, Campus Box 395, Boulder, Colorado 80309-0395,
USA
The first author was partially supported by NSF DMS 0074531. 相似文献
2.
Franki Dillen Johan Fastenakels Joeri Van der Veken Luc Vrancken 《Monatshefte für Mathematik》2007,152(2):89-96
In this article we study surfaces in
for which the unit normal makes a constant angle with the
-direction. We give a complete classification for surfaces satisfying this simple geometric condition. 相似文献
3.
Min Ho Lee 《Monatshefte für Mathematik》2004,141(3):187-196
Let
be an equivariant holomorphic map of symmetric domains associated to a homomorphism
of semisimple algebraic groups defined over
. If
and
are torsion-free arithmetic subgroups with
, the map induces a morphism :
of arithmetic varieties and the rationality of is defined by using symmetries on
and
as well as the commensurability groups of and . An element
determines a conjugate equivariant holomorphic map
of which induces the conjugate morphism
of . We prove that is rational if is rational. 相似文献
4.
In this paper we deal with the following problem. Let (M
n
,〈,〉) be an n-dimensional Riemannian manifold and
an isometric immersion. Find all Riemannian metrics on M
n
that can be realized isometrically as immersed hypersurfaces in the Euclidean space
. More precisely, given another Riemannian metric
on M
n
, find necessary and sufficient conditions such that the Riemannian manifold
admits an isometric immersion
into the Euclidean space
. If such an isometric immersion exists, how can one describe
in terms of f?
Author’s address: Thomas Hasanis and Theodoros Vlachos, Department of Mathematics, University of Ioannina, 45110 Ioannina,
Greece 相似文献
5.
6.
L. Olsen 《Monatshefte für Mathematik》2003,140(4):335-350
Let be a subshift modelled by a strongly connected graph, and let
denote the shift. For n , let
be the nth empirical measure, i.e.
where
x
denotes the Dirac measure at x and
denotes the family of probability measures on . We consider continuous deformations of L
n
, i.e. pairs
where X is a metric vector space and
is continuous with respect to the weak topology on
. For a sequence (x
n
)
n
in X, we write
for the set of accumulation points of (x
n
)
n
. Assume that T and U are subsets of X, and define
In previous work we computed the Hausdorff dimension of the sets (T,U). In this paper we prove that these sets are dimensionless, i.e. if t denotes the Hausdorff dimension of (T,U) and h is a dimension function of the form h(r) = r
t
L(t) where L is a slowly varying function, then
provided that
. In particular,
or
. This implies that various sets of divergence points associated with different multifractal spectra (e.g. local dimensions, local entropies, local Lyapunov exponents, ergodic averages) are dimensionless. 相似文献
7.
Manfred Stoll 《Monatshefte für Mathematik》2005,144(2):131-139
Let B denote the unit ball in n, n 1, and let and
denote the volume measure and gradient with respect to the Bergman metric on B. In the paper we consider the weighted Dirichlet spaces
,
, and weighted Bergman spaces
,
,
, of holomorphic functions f on B for which
and
respectively are finite, where
and
The main result of the paper is the following theorem.Theorem 1. Let f be holomorphic on B and
.(a) If
for some
, then
for all p,
, with
.(b) If
for some p,
, then
for all
with
. Combining Theorem 1 with previous results of the author we also obtain the following.Theorem 2. Suppose
is holomorphic in B. If
for some p,
, and
, then
. Conversely, if
for some p,
, then the series in * converges. 相似文献
8.
This paper has two parts. In the first part, we study shift coordinates on a sphere S equipped with three distinguished points and a triangulation whose vertices are the distinguished points. These coordinates
parametrize a space
that we call an unfolded Teichmüller space. This space contains Teichmüller spaces of the sphere with
boundary components and
cusps (which we call generalized pairs of pants), for all possible values of
and
satisfying
. The parametrization of
by shift coordinates equips this space with a natural polyhedral structure, which we describe more precisely as a cone over
an octahedron in
. Each cone over a simplex of this octahedron is interpreted as a Teichmüller space of the sphere with
boundary components and
cusps, for fixed
and
, the sphere being furthermore equipped with an orientation on each boundary component. There is a natural linear action of
a finite group on
whose quotient is an augmented Teichmüller space in the usual sense. We describe several aspects of the geometry of the space
. Stretch lines and earthquakes can be defined on this space. In the second part of the paper, we use the shift coordinates
to obtain estimates on the behaviour of stretch lines in the Teichmüller space of a surface obtained by gluing hyperbolic
pairs of pants. We also use the shift coordinates to give formulae that express stretch lines in terms of Fenchel-Nielsen
coordinates. We deduce the disjointness of some stretch lines in Teichmüller space. We study in more detail the case of a
closed surface of genus 2.
Authors’ addresses: A. Papadopoulos, Institut de Recherche Mathématique Avancée, Université Louis Pasteur and CNRS, 7 rue
René Descartes, 67084 Strasbourg Cedex, France and Max-Planck-Institut für Mathematik, Vivatsgasse 7, 53111 Bonn, Germany;
G. Théret, Institut de Recherche Mathématique Avancée, Université Louis Pasteur and CNRS, 7 rue René Descartes, 67084 Strasbourg
Cedex, France and Department of Mathematical Sciences, University of Aarhus, Ny Munkegade, Building 1530, DK-8000 Aarhus C,
Denmark 相似文献
9.
Let
be an arbitrary real normed space of finite dimension d ≥ 2. We define the metric capacity of
as the maximal
such that every m-point metric space is isometric to some subset of
(with metric induced by
). We obtain that the metric capacity of
lies in the range from 3 to
, where the lower bound is sharp for all d, and the upper bound is shown to be sharp for d ∈ {2, 3}. Thus, the unknown sharp upper bound is asymptotically linear, since it lies in the range from d + 2 to
.
Research supported by the German Research Foundation, Project AV 85/1-1. 相似文献
10.
In this paper, we establish several decidability results for pseudovariety joins of the form
, where
is a subpseudovariety of
or the pseudovariety
. Here,
(resp.
) denotes the pseudovariety of all
-trivial (resp.
-trivial) semigroups. In particular, we show that the pseudovariety
is (completely) κ-tame when
is a subpseudovariety of
with decidable κ-word problem and
is (completely) κ-tame. Moreover, if
is a κ-tame pseudovariety which satisfies the pseudoidentity x1 ⋯ xryω+1ztω = x1 ⋯ xryztω, then we prove that
is also κ-tame. In particular the joins
,
,
, and
are decidable.
Partial support by FCT, through the Centro de Matemática da Universidade do Porto, is also gratefully acknowledged.
Partial support by FCT, through the Centro de Matemática da Universidade do Minho, is also gratefully acknowledged. 相似文献
11.
Klaus Langmann 《Monatshefte für Mathematik》2004,143(3):205-227
We show that the unsolvability of the Diophantine equation
is equivalent to a good uniform distribution of the set
. The proof depends on the asymptotic evaluation of the Gauss sum
. 相似文献
12.
For each integer n 2, let
be the index of composition of n, where
. For convenience, we write (1)=(1)=1. We obtain sharp estimates for
and
, as well as for
and
. Finally we study the sum of running over shifted primes.Research supported in part by a grant from NSERC.Research supported by the Applied Number Theory Research Group of the Hungarian Academy of Science and by a grant from OTKA. 相似文献
13.
Given an almost complex structure J in a cylinder of
(p > 1) together with a compatible symplectic form
and given an arbitrary J-holomorphic curve
without boundary in that cylinder, we construct an holomorphic perturbation of
, for the canonical complex structure J
0 of
, such that the distance between these two curves in W
1,2 and
norms, in a sub-cylinder, are controled by quantities depending on J,
and by the area of
only. These estimates depend neither on the topology nor on the conformal class of
. They are key tools in the recent proof of the regularity of 1-1 integral currents in [RT].Received: 2 October 2003, Accepted: 18 November 2003, Published online: 25 February 2004 相似文献
14.
Angela Pistoia Olivier Rey 《Calculus of Variations and Partial Differential Equations》2003,18(3):243-251
Let
,
, be a bounded domain as defined by Flucher, Garroni and Müller [6], which has a singular point
such that the Robins function achieves its infimum at
. Considering the elliptic problem
in
; u = 0 on
, with p = (N + 2)/(N-2),
, and
a minimizing solution of
,
concentrates at
as
goes to zero.Received: 15 September 2002, Accepted: 5 November 2002, Published online: 16 May 2003Mathematics Subject Classification:
35J65Angela Pistoia: The author is supported by M.U.R.S.T., project Metodi variazionali e topologici nello studio di fenomeni non lineari 相似文献
15.
We prove effective upper bounds for the almost periodicity of polynomial Euler products
in the half-plane of absolute convergence. From this we deduce estimates for the roots of the equation
, where c is any non-zero complex number which is attained by
. The method relies mainly on effective diophantine approximation.The first author was supported by a grant of the Humboldt Foundation. 相似文献
16.
Finn and Kosmodemyanskii, Jr. gave an example of a domain
containing a disk
, and of a family of domains
converging to
as
, such that the heights u
t
of capillary surfaces in vertical tubes with the sections
in a gravity field g satisfy
for every
, but for which u
1< u
0 over
for all g > 0. In subsequent work, Finn and Lee characterized the most general convex
that leads to such a discontinuous transition when
is a disk. It has been suggested that the cause for this curious behavior is related to the fact that in all cases considered the boundaries of the
have a discontinuity in their curvatures, that is bounded below in magnitude. In the present note we present an alternative form of the example, in which the domains
are disks concentric to
. Thus, the limited smoothness in the original example of the convergence to
of the approxim
ating domains cannot be viewed as the root cause of the anomaly. The procedure presented here leads to explicit bounds, which were not available in the earlier forms of the example.Received: 3 September 2002, Accepted: 17 February 2003, Published online: 1 July 2003Mathematics Subject Classification:
76B45, 53A10, 49Q10 相似文献
17.
In [C.K. Chui and X.L. Shi, Inequalities of Littlewood-Paley type for frames and wavelets, SIAM J. Math. Anal., 24 (1993), 263–277], the authors proved that if
is a Gabor frame for
with frame bounds A and B, then the following two inequalities hold:
and
. In this paper, we show that similar inequalities hold for multi-generated irregular Gabor frames of the form
, where Δ
k
and Λ
k
are arbitrary sequences of points in
and
, 1 ≤ k ≤ r.
Corresponding author for second author
Authors’ address: Lili Zang and Wenchang Sun, Department of Mathematics and LPMC, Nankai University, Tianjin 300071, China 相似文献
18.
L. Olsen 《Monatshefte für Mathematik》2005,146(2):143-157
For a probability measure μ on a subset of
, the lower and upper Lq-dimensions of order
are defined by
We study the typical behaviour (in the sense of Baire’s category) of the Lq-dimensions
and
. We prove that a typical measure μ is as irregular as possible: for all q ≥ 1, the lower Lq-dimension
attains the smallest possible value and the upper Lq-dimension
attains the largest possible value. 相似文献
19.
P. Courilleau J. Mossino 《Calculus of Variations and Partial Differential Equations》2004,20(1):65-91
We study the limit behaviour of some nonlinear monotone equations, such as:
, in a domain
which is thin in some directions (e.g.
is a plate or a thin cylinder). After rescaling to a fixed domain
, the above equation is transformed into:
, with convenient operators
and
. Assuming that
and the inverse of
have particular forms and satisfy suitable compensated compactness assumptions, we prove a closure result, that is we prove that the limit problem has the same form. This applies in particular to the limit behaviour of nonlinear monotone equations in laminated plates.Received: 16 October 2002, Accepted: 12 June 2003, Published online: 22 September 2003Mathematics Subject Classification (2000):
35B27, 35B40, 74Q15 相似文献
20.
We present a characterization of ideal knots, i.e., of closed knotted curves of prescribed thickness with minimal length, where we use the notion of global curvature for the definition of thickness. We show with variational methods that for an ideal knot
, the normal vector
at a curve point
is given by the integral over all vectors
against a Radon measure, where
realizes the given thickness. As geometric consequences we obtain in particular, that points without contact lie on straight segments of
, and for points
with exactly one contact point
we have that
points exactly into the direction of
Moreover, isolated contact points lie on straight segments of
, and curved arcs of
consist of contact points only, all realizing the prescribed thickness with constant (maximal) global curvature.Received: 1 January 2003, Accepted: 12 March 2003, Published online: 1 July 2003Mathematics Subject Classification (2000):
53A04, 57M25, 74K05, 74M15, 92C40 相似文献