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1.
Bernd Heinrich Matzat 《manuscripta mathematica》1979,27(1):103-111
Algebraic function fields and algebraic number fields with the Mathieu group M11 as Galois group over the ground field
will be constructed. 相似文献
2.
Letp be an odd prime and
the finite field withp elements. In the present paper we shall investigate the number of points of certain quadratic hypersurfaces in the vector space
and derive explicit formulas for them. In addition, we shall show that the class number of the real quadratic field
(wherep1 (mod 4)) over the field of rational numbers can be expressed by means of these formulas. 相似文献
3.
E. P. Golubeva 《Journal of Mathematical Sciences》2003,118(1):4740-4752
Let h(d) be the class number of the field
and let
be the Lévy constant. A connection between these constants is studied. It is proved that if d is large, then the value h(d) increases, roughly speaking, at the rate
as
grows. A similar result is obtained in the case where the value
is close to
, i.e., to the least possible value. In addition, it is shown that the interval
contains no values of
for prime p such that p 3 (mod 4). As a corollary, a new criterion for the equality h(d)=1 is obtained. Bibliography: 14 titles. 相似文献
4.
There are exactlytwo non-equivalent [32,11,12]-codes in the binaryReed-Muller code
which contain
and have the weight set {0,12,16,20,32}. Alternatively,the 4-spaces in the projective space
over the vector space
for which all points have rank 4 fall into exactlytwo orbits under the natural action of PGL(5) on
. 相似文献
5.
Klaus Reuter 《Order》1989,6(3):277-293
It is known that for incidence structures
and
, max
, wheref dim stands for Ferrers relation. We shall show that under additional assumptions on
and
, both bounds can be improved. Especially it will be shown that the square of a three-dimensional ordered set is at least four-dimensional. 相似文献
6.
With
, we here construct, for each positive integer N, a smooth function
of degree zero so that there must be at least N singular points for any map that minimizes the energy
in the family
. The infimum of over U(g) is strictly smaller than the infimum of over the continuous functions in U(g). There are some generalizations to higher dimensions.Research partially supported by the National Science FoundationResearch supported by an Alfred P. Sloan Graduate Fellowship 相似文献
7.
Let
denote the closed subspace of
consisting of analytic functions in the unit disk
. For certain class of subharmonic
, the Hankel operatorH
b on
with symbol
is studied. Criteria for boundedness and compactness of such kind of Hankel operators are presented.R. Rochberg's research was partially supported by a grant from the National Science Foundation. 相似文献
8.
Let
and
the foliations by the null geodesics of some lorentzian metricg on the torus
. We analyse how geodesic completeness properties ofg are related to the dynamics of
and
. 相似文献
9.
J. Hartmann 《Transformation Groups》2001,6(2):157-164
Let :GGl(n,
) be a representation of a finite groupG over a field
such that the ring of invariants
is a polynomial algebra
. It is known that in the nonmodular case (i.e., when the order of the group is not divisible by the characteristic of
), the invariants ofG acting on the tensor product
of a polynomial and an exterior algebra are given by
,d denoting the exterior derivative. We show that in the modular case, the ring of invariants in
is of this form if and only if
is a polynomial algebra and all pseudoreflections in (G) are diagonalizable. 相似文献
10.
Oswald Riemenschneider 《manuscripta mathematica》1974,14(1):91-99
Let
be a 1-convex holomorphic mapping between complex spaces
resp.S, and let
be the blowingdown factorization of
over S. We prove in part 1 of the present note: The fiber –1(s0) over a point s0S is the Remmert quotient of
if and only if every holomorphic function on
(defined in a neighborhood of the exceptional subvariety of that fiber) can be extended holomorphically to
. This is true, for instance, in the case:
flat, S reduced at s0 and dim
, =const for all sS. In part 2, we use this result to obtain the following: For any Riemann surface R with genus g2 there exists a 2-dimensional normal complex analytic singularity X such that the minimal resolution
of X contains R as exceptional subvariety, and
has a deformation over the unit disc S={|s|<1} which can not be blown down to a deformation of X. 相似文献
11.
Hans-Georg Rück 《manuscripta mathematica》1995,88(1):387-407
LetL be an imaginary quadratic extension of the rational function field
. We prove transformation rules for the theta series corresponding to partial zeta functions of the extension
. 相似文献
12.
We show that every sub-weak embedding of any singular (degenerate or not) orthogonal or unitary polar space of non-singular rank at least 3 in a projective space PG
,
a commutative field, is the projection of a full embedding in some subspace PG
of PG
, where PG
contains PG
and
is a subfield of
. The same result is proved in the symplectic case under the assumption that the field over which the polarity is defined is perfect if the characteristic is 2 and if each secant line of the embedded polar space contains exactly two points of . This completes the classification of all sub-weak embeddings of orthogonal, symplectic and unitary polar spaces (singular or not; degenerate or not) of non-singular rank at least 3 and defined over a commutative field
, where in the characteristic 2 case
is perfect if the polar space is symplectic and the degree of the embedding is 2. 相似文献
13.
Manuela Sobral 《Applied Categorical Structures》1996,4(1):97-106
The paper deals with (effective) descent morphisms for subfibrations
X of the basic fibration Top/X, for topological spaces X and classes
of continuous functions stable under pullback. For a category with pullbacks, we prove the stability under pullback of effective
-descent morphisms for a class
satisfying some suitable conditions. This plays a rôle in relating effective
-descent to effective global-descent and enables us to obtain a criterion for effective étale-descent. We also show that the inclusion of the class of effective global-descent maps in the class surjective effective étale-descent is strict.Partial financial support by Centro de Matemática da Universidade de Coimbra is gratefully acknowledged. 相似文献
14.
Hermann Hähl 《Geometriae Dedicata》1990,36(2-3):181-197
New results of Salzmann and Hubig say that a 16-dimensional (locally) compact topological projective plane in which the group
of continuous collineations has dimension 40 is a translation plane. It is therefore important to determine all 16-dimensional locally compact translation planes with dim
40. From previous work of the author ([10]), it is known that such a plane is either the classical octonion plane, or dim
=40 and
contains a subgroup isomorphic to the compact exceptional group G2, but no larger compact simple subgroup. In the present paper, all planes satisfying the latter property more generally with dim
38 are explicitly determined. Together with the classification of all 16-dimensional locally compact translation planes in which
contains Spin(7) given by the author in [8], one thus knows all 16-dimensional locally compact translation planes with
containing G2 and dim
38. Via suitable Baer subplanes, the classification makes use of analogous results for 8-dimensional planes ([7]).
Meinem verehrten Lehrer Helmut Salzmann zum 60. Geburtstag 相似文献
Meinem verehrten Lehrer Helmut Salzmann zum 60. Geburtstag 相似文献
15.
Gerd Herzog 《Periodica Mathematica Hungarica》1995,30(3):205-210
Given a sequence (
n
)
n
in
with
there are functions
such that
, is a dense subset of
, and the set of functions with this property is residual in
. We will show that in
and some related Banach spaceX there are functionsf with
is dense in
, and we will give a sufficient condition when the set of such functions is residual inX. 相似文献
16.
Judita Lihová 《Czechoslovak Mathematical Journal》1999,49(1):67-80
Let
be a partially ordered set, Int
the system of all (nonempty) intervals of
partially ordered by the set-theoretical inclusion
. We are interested in partially ordered sets
with Int
isomorphic to Int
. We are going to show that they correspond to couples of binary relations on A satisfying some conditions. If
is a directed partially ordered set, the only
with Int
isomorphic to Int
are
corresponding to direct decompositions
of
(
denotes the dual of
. The present results include those presented in the paper [11] by V. Slavík. Systems of intervals, particularly of lattices, have been investigated by many authors, cf. [1]–[11]. 相似文献
17.
ALAIN HÉNAUT 《Geometriae Dedicata》1997,65(1):89-101
A d-web in (
,0) is given by d complex analytic foliations of codimension one in (
,0) which are in general position. A d-web
in (
,0) is linear if all the leaves are (pieces of) hyperplanes in
and
is algebraic if it is associated, by duality, to a nondegenerate algebraic curve in
of degree d. We characterize linear webs in (
,0). We give explicit conditions under which a linear d-web in (
,0) is algebraic and we obtain equations for
in this case. Some related problems are discussed and some questions are posed. 相似文献
18.
Andrew Ranicki 《K-Theory》1989,3(2):163-195
The cobordism groups of quadratic Poincaré complexes in an additive category with involution
are identified with the Wall L-groups of quadratic forms and formations in
, generalizing earlier work for modules over a ring with involution by avoiding kernels and cokernels. 相似文献
19.
Roman Drnovšek 《Integral Equations and Operator Theory》2001,39(3):253-266
Let
be a collection of bounded operators on a Banach spaceX of dimension at least two. We say that
is finitely quasinilpotent at a vectorx
0X whenever for any finite subset
of
the joint spectral radius of
atx
0 is equal 0. If such collection
contains a non-zero compact operator, then
and its commutant
have a common non-trivial invariant, subspace. If in addition,
is a collection of positive operators on a Banach lattice, then
has a common non-trivial closed ideal. This result and a recent remarkable theorem of Turovskii imply the following extension of the famous result of de Pagter to semigroups. Let
be a multiplicative semigroup of quasinilpotent compact positive operators on a Banach lattice of dimension at least two. Then
has a common non-trivial invariant closed ideal.This work was supported by the Research Ministry of Slovenia. 相似文献
20.
Summary Let
denote the extended Weyl algebra,
, the Weyl algebra. It is well known that every element of
of the formA=B
k
*
B
k
is positive. We prove that the converse implication also holds: Every positive elementA in
has a quadratic sum factorization for some finite set of elements (B
k
) in
. The corresponding result is not true for the subalgebra
. We identify states on
which do not extend to states on
. It follows from a result of Powers (and Arveson) that such states on
cannot be completely positive. Our theorem is based on a certain regularity property for the representations which are generated by states on
, and this property is not in general shared by representations generated by states defined only on the subalgebra
.Work supported in part by the NSF 相似文献