共查询到20条相似文献,搜索用时 406 毫秒
1.
Tamás Szönyi 《Graphs and Combinatorics》1991,7(3):279-287
A complete arc in a projective plane of orderq has at least
points. We show the existence of completek-arcs having
points in certain André planes of square order. Moreover our construction shows that for all
x > \sqrt q \log q$$
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there are completek-arcs withx < k < Cxlogq, for some absolute constantC. 相似文献
2.
Tamás Szönyi 《Graphs and Combinatorics》1992,8(1):81-89
A complete are in a projective plane of orderq has at least
points. We show the existence of completek-arcs having
points in certain André-planes of square order. Moreover our construction shows that for all
there are completek-arcs withx<k<Cx logq, for some absolute constantC. 相似文献
3.
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
4.
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
5.
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
6.
This paper deals with the structure, the existence conditions and the design methods of the stable and structurally stable regulators for the singular system
. Two classes of normal regulators are proposed: the first class of them, using the measurementy as its input, is applicable to the situation where the structural parameter pecturbations (especiallyE) is constrained. On the other hand, the second class of them, usingy and
as its input, is applicable to arbitrsry perturbations in the sense for singular systems of the structural parameters. But this is done at the cost of additional equipment to measure the
(the speed ofy). 相似文献
7.
D. N. Dudin 《Mathematical Notes》1968,3(1):42-44
For an algebra
of subsets of a set X there is constructed a set
and an algebra of its subsets so that the mapping
is a one-to-one correspondence between
and
and for each additive measure on
the measure
on
defined by the equation
is countably additive.Translated from Matematicheskie Zametki, Vol. 3, No. 1, pp. 71–76, January, 1968.The author wishes to express his deep appreciation to S. V. Fomin, under whose guidance this paper was written. 相似文献
8.
Edgar R. Lorch 《Integral Equations and Operator Theory》1981,4(3):422-434
The objects studied are the subalgebras of
which contain co. These are isometrically isomorphic to the algebras C(
) where
is a compactification of a discrete denumerable set N . It is shown: 1) If
is metric then there is a projection of norm 1, P: C(
) C(
) with kernel co defined by PF = f o where is a retraction of
onto
=
– N . 2) If
is metric, then the group of homeomorphisms of
is isomorphic to a complete group of permutations of the natural numbers . 3) The group of homeomorphisms of a compact metric space is the homomorphic image of a complete group of permutations of ("complete" means "no outer automorphisms, trivial center"). 相似文献
9.
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
10.
Günter Mayer 《Numerische Mathematik》1985,46(1):69-83
Summary Let
be a real irreduciblen×n interval matrix. Then a necessary and sufficient condition is given for the sequence
of the powers of an interval matrix
to converge to a matrix
which is not the null matrix. In addition a criterion for
is proved to decide whether the limit matrix
satisfies the condition of symmetry
. 相似文献
11.
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
12.
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
13.
We consider the on-line computation of the lattice of maximal antichains of a finite poset
. This on-line computation satisfies what we call the linear extension hypothesis: the new incoming vertex is always maximal in the current subposet of
. In addition to its theoretical interest, this abstraction of the lattice of antichains of a poset has structural properties which give it interesting practical behavior. In particular, the lattice of maximal antichains may be useful for testing distributed computations, for which purpose the lattice of antichains is already widely used. Our on-line algorithm has a run time complexity of
, where |P| is the number of elements of the poset,
, |MA(P)| is the number of maximal antichains of
and (P) is the width of
. This is more efficient than the best off-line algorithms known so far. 相似文献
14.
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
15.
Let (G,
) denote a finite groupG with fibration
. The group Aut (G,
) of operators of (G,
) is closely related to the group of collineations of (G,
). In this paper we investigate the geometric properties imposed on (G,
) by requiring that Aut (G,
)=AutG. We find that in many instances this algebraic property restricts the geometry to a very special form.Dedicated to Professor Helmut Karzel on the occasion of his 60th birthday. 相似文献
16.
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
17.
By removing the components of at-spread
of a finite projective spacePG(d, q) from each hyperplane ofPG(d, q), the blocks of a regular group divisible design
are obtained We characterize geometrict-spreads as thoset-spreads
which are such that the dual of
is also a group divisible design. 相似文献
18.
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
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.
William M. McGovern 《Inventiones Mathematicae》1989,97(1):209-217
Summary LetG be a complex semisimple algebraic group with Lie algebra
. Let
be a nilpotentG-orbit,
its ring of regular functions. We derive a formula for
as aG-module and prove some partial results on
a cover of
. We then relate this formula to various existing multiplicity formulas forK-types in Harish-Chandra bimodules ofG.Supported by National Science Foundation Grant DMS-8505550 相似文献