共查询到20条相似文献,搜索用时 31 毫秒
1.
Dr. Martin Funk 《Monatshefte für Mathematik》1982,93(1):1-14
Let
be a Minkowski-(incidence-)plane and let
be the group of free projectivities of
, i. e. the subgroup generated by pairs of proper perspectivities with identical centers. Our theorem then asserts that
is miquelian if
satisfies condition (P
5), i. e. every free projectivity with 5 fixed points is the identity. But first a lemma is shown, which holds in Möbius- and Laguerre-(incidence-)planes too: if
fulfills (P
5), then every affine derivation of
is pappian. 相似文献
2.
Prof. Ottmar Loos 《Monatshefte für Mathematik》1978,86(2):107-129
Every Jordan pair
defines an algebraic varietyX containing
as a dense open subset.X is projective (affine) if and only if
is separable (radical). The Picard group ofX is generated by the irreducible factors of the generic norm of
. If
is separable then the automorphism group ofX is the projective group of
. 相似文献
3.
Ignacio Bajo 《Monatshefte für Mathematik》1994,118(1-2):1-6
Let
be a complex Lie algebra,
its underlying real Lie algebra,
a real form of
and ·, · the euclidean product induced by the real part of an hermitian inner product on
. Let aut
be the Lie algebra of skew-symmetric derivations of
. We give necessary and sufficient conditions to ensure that aut
is composed of skew-hermitian derivations. As an application, we study holomorphy in large subgroups of isometries of Lie groups. 相似文献
4.
Dr. Detlev Poguntke 《Monatshefte für Mathematik》1976,82(1):31-50
This is a continuation of the paper Zwei Klassen lokalkompakter maximal fastperiodischer Gruppen, [6]. In [6], the classes
and
were introduced. We give sufficient conditions to conclude thatG is in
if one knows thatG/G
0 is in
. If a groupG is in
and ifG satisfies the Chu-duality then all closed subgroups ofG satisfy the Chu-duality. The Chu-quasi-dual of the Heisenberg groupH with integral coefficients is computed. It is shown thatH does not satisfy the Chu-duality, thatH is in
, and thatH is not in
. 相似文献
5.
Graeme West 《Integral Equations and Operator Theory》1995,22(3):352-359
Suppose
is a von Neumann algebra on a Hilbert space
and
is any ideal in
. We determine a topology
on
, for which the members of
that are
to norm continuous are exactly those in
; and a bornology
on
such that the elements of
which map the unit ball to an element of
, equivalently those members of
that are norm to
bounded, are exactly those in
. This is achieved via analogues of the notions of injectivity and surjectivity in the theory of operator ideals on Banach spaces. 相似文献
6.
Prof. Dr. Hellmuth Stachel 《Monatshefte für Mathematik》1979,88(1):45-54
TheBlaschke-Grünwald-map associates to each surface in the quasielliptic space a planar euclidean two-parameter motion
. Using this map we find kinematic meanings of the Gaussian quasielliptic curvature and furthermore some theorems about the asymptotic motions of
. The kinematic equivalent of the relation of left-conjugated tangents in points of is a regular or singular projectivity on each poleline of
. This projectivities have been studied already byH. J. E. Beth andW. v.d. Woude. We show that in every position the quadratic curvature transformations of almost all one-parameter motions of
are determined by . 相似文献
7.
LetF be an algebraic number field and F such thatx
m– is irreducible, wherem is an integer. Let
be a prime ideal inF with
. The prime decomposition of
in
is explicitly obtained in the following cases. Case 1:
, (a,m) = 1 (where
means
, 0
). Case 2:m lt, wherel is a prime andl 0
. Case 3:m 0
and every prime that dividesm also dividespf–1. It is not assumed that thev
th roots of unity are inF for anyv 2. 相似文献
8.
Takuya Hara 《Integral Equations and Operator Theory》1992,15(4):551-567
Let
be a Hilbert space. A continuous positive operatorT on
uniquely determines a Hilbert space
which is continuously imbedded in
and for which
with the canonical imbedding
. A Kreîn space version of this result, however, is not valid in general. This paper provides a necessary and sufficient condition for that a continuous selfadjoint operatorT uniquely determines a Kreîn space (
) which is continuously imbedded in
and for which
with the canonical imbedding
. 相似文献
9.
S. Zhang 《Algebra Universalis》1996,35(4):485-505
Let
be a variety of completely regular semigroups. Define
C
* to be the class of all completely regular semigroupsS whose least full and self-conjugate subsemigroupC
*(S) belongs to
. ThenC
* is an operator on the lattice
of varieties of completely regular semigroups. In this note we show that the order ofC
* is infinite. This fact yields that the Mal'cev project is not associative on
. We describe
(C
*)1,
andi 0, in terms of -invariant normal subgroups of the free group over a countably infinite set. The lattice theoretic properties ofC
* are also studied.Presented by W. Taylor. 相似文献
10.
In this paper we investigate functorial properties of the Segal algebra
which consists of all functionsf in Wiener's algebra onG with Fourier transform
in Wiener's algebra on the dual group
. Especially
may serve as a very large and natural domain for Poisson's formula. Moreover, there is introduced a Segal algebraE
0(G) containing
as a subspace, but still eachfE
0(S) satisfies Poisson's formula. 相似文献
11.
Johannes Schoissengeier 《Monatshefte für Mathematik》1992,114(2):139-147
A proof of the formula
for locally compact fields
andC
1-isomorphisms :UV, whereU andV are open subsets of
, was never published. In this paper we give two short proofs, one of them is a more elementary variant of the other. 相似文献
12.
Aleksandar Ivić 《Monatshefte für Mathematik》1987,104(1):17-27
The existence of zeros ofZ
(k)(t) in short intervals of the type [T, T+H] is established, whereHT
a(k)logT,
. Hitherto the sharpest bounds for the constanta(k) are obtained by employing a certain exponential averaging technique and the estimation of the relevant exponential sums. Bounds for
are also derived, under the assumption that
orZ(t) does not vanish in certain short intervals. 相似文献
13.
Xingde Dai 《Integral Equations and Operator Theory》1997,27(3):294-313
Let be a nest in a separably acting factor
. We present conditions for a factor
to be a bimodule of the nest subalgebraalgß in
which is singly generated in the norm topology. Some relevant results about the compact ideal
, the quasitriangular algebra and the Calkin algebra are established.This work was supported, in part, by funds provided by the University of North Carolina at Charlotte. 相似文献
14.
Mervyn J. Silvapulle Pranab K. Sen 《Annals of the Institute of Statistical Mathematics》1993,45(1):159-171
Consider the linear modelY=X+E in the usual matrix notation where the errors are independent and identically distributed. We develop robust tests for a large class of one- and two-sided hypotheses about when the data are obtained and tests are carried out according to a group sequential design. To illustrate the nature of the main results, let
and
be anM- and the least squares estimator of respectively which are asymptotically normal about with covariance matrices 2(X
t
X)–1 and 2(X
t
X)–1 respectively. Let the Wald-type statistics based on
and
be denoted byRW andW respectively. It is shown thatRW andW have the same asymptotic null distributions; here the limit is taken with the number of groups fixed but the numbers of observations in the groups increase proportionately. Our main result is that the asymptotic Pitman efficiency ofRW relative toW is (2/2). Thus, the asymptotic efficiency-robustness properties of
relative to
translate to asymptotic power-robustness ofRW relative toW. Clearly, this is an attractive result since we already have a large literature which shows that
is efficiency-robust compared to
. The results of a simulation study show that with realistic sample sizes,RW is likely to have almost as much power asW for normal errors, and substantially more power if the errors have long tails. The simulation results also illustrate the advantages of group sequential designs compared to a fixed sample design, in terms of sample size requirements to achieve a specified power. 相似文献
15.
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
16.
Mikael R?rdam 《K-Theory》1995,9(1):31-58
A classification is given of the simple Cuntz-Krieger algebras
. It is proved that these algebras are classified up to stable isomorphism by their K0-group. Thus the sign of the determinant of 1 —A is not an isomorphism invariant. The (non-stabilized) isomorphism type of
is determined by K0(
) together with the position of the class of the unit of
. 相似文献
17.
Frieder Haug 《Order》1994,11(1):61-76
We discuss the question, whether each automorphism group (of cardinality at most
) of a linear order is embeddable into the automorphism group of the real line. We show that the answer to this question is independent of the axioms of ZFC: the answer is positive, if we assume
<
and Souslin's hypothesis; the answer is negative, if we assume
orV=L. 相似文献
18.
The Jacobian conjecture for polynomial maps :K
n
K
n
is shown to be equivalent to a certain Lie algebra theoretic property of the Lie algebra
of formal vector fields inn variables. To be precise, let
be the unique subalgebra of codimensionn (consisting of the singular vector fields),H a Cartan subalgebra of
,H
the root spaces corresponding to linear forms onH and
. Then every polynomial map :K
n
K
n
with invertible Jacobian matrix is an automorphism if and only if every automorphism of
with (A)
satisfies (A)=A. 相似文献
19.
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
20.
Aparna W. Higgins 《Algebra Universalis》1985,20(2):179-193
Given a group G and a descending chainG
0,G
1,...,G
n, of normal subgroups ofG, we prove that there exists a universal algebra
, such that the chain ...Wn(
)...W1(
}) W0(
)W(
) is isomorphic to the chain ...G
n ...G
1G
0G, where W(
) is the group of weak automorphisms of
, and Wn(
) is the group of weak automorphisms of
that leaves alln-ary operations fixed.We also prove that there are an infinite number of non-isomorphic algebras that satisfy the above.These results are a generalization of those proved by J. Sichler, in the special case when G=G0, and G1=G2=...=Gn=....Presented by J. Mycielski.This paper comprises part of the author's doctoral dissertation at the University of Notre Dame in 1983. The author wishes to express her deep gratitude to Professor Abraham Goetz for suggesting this problem, for being extremely generous with his time and experience, and for giving her his constant encouragement. The author also thanks the reviewer for his helpful comments. 相似文献