共查询到20条相似文献,搜索用时 31 毫秒
1.
Micheline Vigué-Poirrier 《manuscripta mathematica》1986,56(2):177-191
Let X be a nilpotent space such that it exists k1 with Hp (X,) = 0 p > k and Hk (X,) 0, let Y be a (m–1)-connected space with mk+2, then the rational homotopy Lie algebra of YX (resp.
is isomorphic as Lie algebra, to H* (X,) (* (Y) ) (resp.+ (X,) (* (Y) )). If X is formal and Y -formal, then the spaces YX and
are -formal. Furthermore, if dim * (Y) is infinite and dim H* (Y,Q) is finite, then the sequence of Betti numbers of
grows exponentially. 相似文献
2.
Let m= (1,..., m) denote an ordered field, where i+1>0 is infinitesimal relative to the elements of i, 0 < –i < m (by definition, 0= ). Given a system of inequalities f1 > 0, ..., fs > 0, fs+1 0, ..., fk 0, where fj m [X1,..., Xn] are polynomials such that, and the absolute value of any integer occurring in the coefficients of the fjs is at most 2M. An algorithm is constructed which tests the above system of inequalities for solvability over the real closure of m in polynomial time with respect to M, ((d)nd0)n+m. In the case m=, the algorithm explicitly constructs a family of real solutions of the system (provided the latter is consistent). Previously known algorithms for this problem had complexity of the order ofM(d d
0
m
2U(n)
.Translated from Zapiski Nauchnykh Seminarov Leningradskogo Otdeleniya Maternaticheskogo Instituta im. V. A. Steklova Akad. Nauk SSSR, Vol. 174, pp. 3–36, 1988. 相似文献
3.
It is the aim of the present work to prove, under appropriate conditions, lower estimates for the dimension of w
1 + ... + w
m
over , wherew
1,...,w
m
are given real numbers. In particular, if this dimension ism, i.e. ifw
1,...,w
m
are linearly independent over , we are also interested in a quantitative version of this fact. Our qualitative theorems generalize a result of Nesterenko. Its formulation is quite similar to the axiomatization of methods for algebraic independence, as it became usual during the last decade. 相似文献
4.
Anthony W. Hager Chawne M. Kimber Warren W. McGovern 《Czechoslovak Mathematical Journal》2005,55(2):409-421
Usually, an abelian -group, even an archimedean -group, has a relatively large infinity of distinct a-closures. Here, we find a reasonably large class with unique and perfectly describable a-closure, the class of archimedean -groups with weak unit which are -convex. ( is the group of rationals.) Any C(X, ) is -convex and its unique a-closure is the Alexandroff algebra of functions on X defined from the clopen sets; this is sometimes C(X). 相似文献
5.
B. Heinrich Matzat 《manuscripta mathematica》1985,51(1-3):253-265
A talk at the 1984 Oberwolfach meeting on Algebraic Number Theory will be summarized. It surveyed some new results on the realization of finite groups as Galois groups over the fields and ab, where ab is the maximal abelian extension field of . 相似文献
6.
Aboubakr Lbekkouri 《manuscripta mathematica》1989,65(3):257-273
We are concerned with the following: If k is a quadratic field and N a cyclic unramified extension of degree qn over k, q a prime number, determine N explicitely via a primitive element , i.e., N=k(), in the spirit of Helmut Hasse [3]. We propose a method which determines these extensions, once we are able to specify the arithmetic of a certain field
. To explicit our method, we construct the Hilbert fields of (226) and (646). 相似文献
7.
V. M. Tsvetkov 《Journal of Mathematical Sciences》1999,95(2):2161-2163
It is proved that the rational number field has one, and only one, normal 2-extension (2, t8)/with group isomorphic to
.If is the maximal subfield of a real-closed field, which does not contain
,then the algebraic closure
of is isomorphic to the field
.Bibliography: 7titles.Translated fromZapiski Nauchnykh Seminarov POMI, Vol. 236, 1997, pp. 192–196. 相似文献
8.
Under certain conditions, we show the nonexistence ofan element in the p-th cyclotomicfield over , that satisfies
. As applications, we establish the nonexistence ofsome difference sets and affine difference sets. 相似文献
9.
We show that for each positive integer n there is a finite list of equivalence relations on []
n
with the property that for every other equivalence relation E on []
n
there is X of order type equal to the order type of , such that E[X]
n
is equal to one of the equivalence relations from the list. 相似文献
10.
Gerhard Kowol 《Monatshefte für Mathematik》1982,93(1):15-32
LetA be a topological universal algebra,F(A)=A
A
the full function algebra endowed with the producttopology andP(A) the algebra of polynomial functions onA, i. e. the subalgebra ofF(A) generated by the constant mappings and the identity.A has the local approximation property ifP(A) is dense inF(A)., TopologicalT
2-groupsG (resp.T
2-ringsR) of order >2 have the local approximation property if an only if all proper normal subgroups (resp. ideals) are dense inG (resp.R) andG is non-abelian (R is not a zeroring). In particular all subringsR of satisfying R ( resp. denoting the field of rational resp. real numbers) yield examples of rings having this property thus showing that the local approximation property is a far-reaching generalization of the well-known interpolation property.
Meinem verehten Lehrer, Herrn Professor Dr. E. Hlawka, zum 65. Geburtstag gewidmet 相似文献
Meinem verehten Lehrer, Herrn Professor Dr. E. Hlawka, zum 65. Geburtstag gewidmet 相似文献
11.
I. A. Panin 《Journal of Mathematical Sciences》1984,26(3):1901-1908
This paper describes fields F of nonzero characteristic with the property that for all finite extensions E/F K2E=0. We consider a somewhat wider class of fields which includes finite and separably closed fields. For smooth projective varieties X over such a field we show that the groups H1(X, K2){} and H2(Xet, (2)), NH3(Xet, (2)) and Ch2(X){} are isomorphic. These results are applied to describe the groups SK1 of a smooth affine curve over such a field.Translated from Zapiski Nauchnykh Seminarov Leningradskogo Otdeleniya Matematicheskogo Instituta im. V. A. Steklova AN SSSR, Vol. 116, pp. 108–118, 1982. 相似文献
12.
Hans Peter Paukowitsch 《Archiv der Mathematik》1979,33(1):105-112
Zusammenfassung Die vorgestellte Kennzeichnung für eine reguläreC
2(U)-Hyperflächef(U) mit zusammenhängender offener ParametermengeU
m–1 aus einer Quadrik im reellenm-dimensionalen projektiven Raum
m
,m 3 über dem (m+l)-dimensionalen reellen Vektorraum
m+1 stützt sich auf die ebenen Schnitte vonf(U) durch eine im Punktf(a) der Hyperfläche nichttangentiale Geradeg. Als Anwendung ergeben sich einerseits eine Charakterisierung von Hyperflächen aus einer Quadrik unter Benützung gewisser scheinbarer Umrisse und andererseits eine Verallgemeinerung eines Ergebnisses über die zentralaffine Metrik nach D. Laugwitz. Weiters werden Hyperflächen aus quadratischen Kegeln in
m
mit Hilfe ihrer Schnitte mit Unterräumen geeigneter fester Dimension durch eine Gerade gekennzeichnet.Wir verwenden wie in [6] einen Flächenbegriff unter Berücksichtigung der Quotientenstruktur von
m
im Sinne differenzierbarer Mannigfaltigkeiten. Unter Benützung von Aussagen aus [6] wird für reguläre Hyperflächen in
m
die Existenz entweder einer oskulierenden Quadrik oder eines oskulierenden quadratischen Kegels oder einer oskulierenden Hyperebene in jedem Flächenpunkt nachgewiesen. 相似文献
13.
A. M. Protopopov 《Algebra and Logic》2003,42(4):279-286
We study into the question of whether a partial order can be induced from a partially right-ordered group
onto a space
of right cosets of
w.r.t. some subgroup
of
. Examples are constructed showing that the condition of being convex for
in
is insufficient for this. A necessary and sufficient condition (in terms of a subgroup
and a positive cone
of
) is specified under which an order of
can be induced onto
. Sufficient conditions are also given. We establish properties of the class of partially right-ordered groups
for which
is partially ordered for every convex subgroup
, and properties of the class of groups such that
is partially ordered for every partial right order
on
and every subgroup
that is convex under
. 相似文献
14.
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
15.
In this paper, we generalize Bernstein's theorem characterizing the space
by means of local approximations. The closed interval
is partitioned into disjoint half-intervals on which best approximation polynomials of degree
divided by the lengths of these half-intervals taken to the power
are considered. The existence of the limits of these ratios as the lengths of the half-intervals tend to zero is a criterion for the existence of the
th derivative of a function. We prove the theorem in a stronger form and extend it to the spaces
. 相似文献
16.
In this paper, we construct a naturalC*-dynamical system whose partition function is the Riemann function. Our construction is general and associates to an inclusion of rings (under a suitable finiteness assumption) an inclusion of discrete groups (the associated ax+b groups) and the corresponding Hecke algebras of bi-invariant functions. The latter algebra is endowed with a canonical one parameter group of automorphisms measuring the lack of normality of the subgroup. The inclusion of rings provides the desiredC*-dynamical system, which admits the function as partition function and the Galois group Gal(cycl/) of the cyclotomic extension cycl of as symmetry group. Moreover, it exhibits a phase transition with spontaneous symmetry breaking at inverse temperature =1 (cf. [Bos-C]). The original motivation for these results comes from the work of B. Julia [J] (cf. also [Spe]). 相似文献
17.
Jorge Almeida 《Algebra Universalis》1989,26(1):16-32
For an ordinal and a class
of topological algebras of a given type (which may be infinite and may contain inflnitary operations), an-aryimplicit operation on
is any new-ary operation whose introduction does not eliminate any continuous homomorphisms between members of
. The set of all-ary implicit operations on
is denoted by
and forms an algebra of the given type which is endowed with the least topology making continuous all homomorphisms into members of
. With this topology,
is a topological algebra in which the subalgebra
of all-ary operations on
which are induced by terms is dense, provided that
is closed under the formation of closed subalgebras and finitary direct products. This is obtained by realizing
as an inverse limit of-generated members of
. These results are applied to pseudovarieties of topological and finite algebras.This work was supported, in part, by INIC grant 85/CEX/4. This paper was written while the author was a faculty member at the Universidade do Minho.Presented by Ralph McKenzie. 相似文献
18.
U. Raitums 《Journal of Optimization Theory and Applications》1997,92(3):633-660
This paper considers analogues of the Helmholtz projections of the set of selections of a piecewise smooth multivalued map
, n2. It is shown that, for mn–1 (m=1), the closure of the projection of on the subspace of gradient fields (solenoidal vector fields) is a convex set. For the general case, there are given point-wise conditions on the values of the map which ensure that the closure of the projection of contains the zero element. Possible applications to optimal control problems are discussed. 相似文献
19.
Benjamin A. Lotto 《Integral Equations and Operator Theory》1990,13(2):216-230
For a given functionb in the unit ball ofH
and an arbitraryH
functionm, the question of whenm is a multiplier of the de Branges space
(that is, when
is invariant under multiplication bym) is examined. Some necessary and sufficient conditions thatm be a multiplier of
are found and it is shown that there are no nonconstant inner multipliers of
whenb is a nonconstant extreme point of the unit ball ofH
. A new proof is given of the known fact that
is invariant under multiplication byz whenb is not an extreme point of the unit ball ofH
. Finally, we give a new proof of the known fact that an inner functionm is a multiplier of
forb(z)=(1+z)/2 if and only ifm belongs to the range of
.Some of the work in this paper originally appeared in the author's doctoral disseratation written at the University of California at Berkeley under the supervision of Donald Sarason. 相似文献
20.
R. Ž. Nurpeisov 《Analysis Mathematica》1989,15(2):127-143
H
(G), f(g)H
(G) , (, 1)- OHMC G. , OHMC, A. H. . , . , OHMC, lim supp
n=, , ,n .. . , 117 234 . . - 相似文献