共查询到20条相似文献,搜索用时 492 毫秒
1.
We consider the stable homotopy category S of polyhedra (finite cell complexes). We say that two polyhedra X,Y are in the same genus and write X ∼ Y if X
p
≅ Y
p
for all prime p, where X
p
denotes the image of Xin the localized category S
p
. We prove that it is equivalent to the stable isomorphism X∨B
0 ≅Y∨B
0, where B
0 is the wedge of all spheres S
n
such that π
n
S
(X) is infinite. We also prove that a stable isomorphism X ∨ X ≅ Y ∨ X implies a stable isomorphism X ≅ Y. 相似文献
2.
J H Pathak 《Proceedings Mathematical Sciences》1989,99(3):217-220
LetA andB be two reduced commutative rings with finitely many minimal prime ideals. If the polynomial algebrasA[X
1
…X
n
]=B[Y
1
…Y
n
] whereX
i
,Y
iF are variables overA andB respectively, then there exists an injective ring homomorphism ϕ:A→B such thatB is finitely generated over ϕ(A). 相似文献
3.
Ergodic homeomorphisms T and S of Polish probability spaces X and Y are evenly Kakutani equivalent if there is an orbit equivalence ϕ: X
0 → Y
0 between full measure subsets of X and Y such that, for some A ⊂ X
0 of positive measure, ϕ restricts to a measurable isomorphism of the induced systems T
A
and S
ϕ(A). The study of even Kakutani equivalence dates back to the seventies, and it is well known that any two irrational rotations
of the circle are evenly Kakutani equivalent. But even Kakutani equivalence is a purely measurable relation, while systems
such as irrational rotations are both measurable and topological. 相似文献
4.
Whenϕ is an analytic map of the unit diskU into itself, andX is a Banach space of analytic functions onU, define the composition operatorC
ϕ
byC
ϕ
(f)=f o ϕ, forf∈X. In this paper we show how to use the Calderón theory of complex interpolation to obtain information on the spectrum ofC
ϕ
(under suitable hypotheses onϕ) acting on the Bloch spaceB and BMOA, the space of analytic functions in BMO. To do this we first obtain some results on the essential spectral radius
and spectrum ofC
ϕ
on the Bergman spacesA
pand Hardy spacesH
p,spaces which are connected toB and BMOA by the interpolation relationships [A
1,B]
t
=A
pand [H
1,BMOA]
t
=H
pfor 1=p(1−t). 相似文献
5.
6.
Palanivel Manoharan 《manuscripta mathematica》2008,125(1):127-137
For a fibre preserving map ϕ: E → E on a fibration (E, π, B), we construct a grading preserving map T(ϕ, π) between H*(E) and H*(B) that generalizes the Lefschetz number. If T(ϕ, π) is an isomorphism between H
0(E) and H
0(B), then π restricts to a surjective local diffeomorphism on each connected component of the fixed point set of ϕ under a transversality condition. This yields a characterization for the bundle H → G → G/H to be trivial when π
1 (G/H) = 0. 相似文献
7.
Alexei Vernitski 《Semigroup Forum》2007,75(2):417-426
The set of difunctional binary relations DX plays a special role in representing inverse semigroups by binary relations. However, DX is not an inverse semigroup either with the standard operation ∘, or with an alternative operation introduced in [6]. We
introduce a new binary operation ⋄ on the set BX of binary relations. We demonstrate that (DX, ⋄) is an inverse semigroup, and the symmetric inverse semigroup (IX, ∘) is a subsemigroup of (DX,⋄). 相似文献
8.
Xiong Ping DAI Zuo Ling ZHOU 《数学学报(英文版)》2006,22(1):207-210
Let X be a metrizable space and let φ:R× X → X be a continuous flow on X. For any given {φt}-invariant Borel probability measure, this paper presents a {φt}-invariant Borel subset of X satisfying the requirements of the classical ergodic theorem for the contiImous flow (X, {φt}). The set is more restrictive than the ones in the literature, but it might be more useful and convenient, particularly for non-uniformly hyperbolic systems and skew-product flows. 相似文献
9.
Let A and B be standard operator algebras on Banach spaces X and Y, respectively. The peripheral spectrum σπ (T) of T is defined by σπ (T) = z ∈ σ(T): |z| = maxw∈σ(T) |w|. If surjective (not necessarily linear nor continuous) maps φ, ϕ: A → B satisfy σπ (φ(S)ϕ(T)) = σπ (ST) for all S; T ∈ A, then φ and ϕ are either of the form φ(T) = A
1
TA
2
−1 and ϕ(T) = A
2
TA
1
−1 for some bijective bounded linear operators A
1; A
2 of X onto Y, or of the form φ(T) = B
1
T*B
2
−1 and ϕ(T) = B
2
T*B
−1 for some bijective bounded linear operators B
1;B
2 of X* onto Y.
相似文献
10.
T. A. Beregovaya 《Russian Mathematics (Iz VUZ)》2009,53(11):16-19
Let C be an Abelian group. An Abelian group A from a class X of Abelian groups is said to be
C
H-definable in X if, for any group B ∈ X, the isomorphism Hom(C,A) ≅ Hom(C,B) implies that A ≅ B. If every group from X is
C
H-definable in X, then X is called an
C
H-class. In this paper, we study conditions under which a class of completely decomposable torsion-free Abelian groups is an
C
H-class, where C is a vector group. 相似文献
11.
Andreas Dress 《Annals of Combinatorics》2009,13(2):193-198
In phylogenetic combinatorics, the analysis of split systems is a fundamental issue. Here, we observe that there is a canonical
one-to-one correspondence between split systems on the one, and “even” set systems on the other hand, i.e., given any finite
set X, we show that there is a canonical one-to-one correspondence between the set P (S (X ) ){\mathcal P (\mathcal S (X ) )} consisting of all subsets S{\mathcal S} of the set S (X){\mathcal S (X)} of all splits of the set X (that is, all 2-subsets {A, B}{\{A, B\}} of the power set P (X){\mathcal P (X)} of X for which A ⋃ B = X and A ⋂ B = 0̸ hold) and the set P even (P (X)){\mathcal P ^{even} (\mathcal P (X))} consisting of all subsets E of the power set P (X){\mathcal P (X)} of X for which, for each subset Y of X, the number of proper subsets of Y contained in E is even. 相似文献
12.
Zhen-long Chen San-yang Liu 《应用数学学报(英文版)》2005,21(4):623-636
Let φ be a Hausdorff measure function and A be an infinite increasing sequence of positive integers. The Hausdorff-type measure φ - mA associated to φ and A is studied. Let X(t)(t ∈ R^N) be certain Gaussian random fields in R^d. We give the exact Hausdorff measure of the graph set GrX([0, 1]N), and evaluate the exact φ - mA measure of the image and graph set of X(t). A necessary and sufficient condition on the sequence A is given so that the usual Hausdorff measure function for X([0, 1] ^N) and GrX([0, 1]^N) are still the correct measure functions. If the sequence A increases faster, then some smaller measure functions will give positive and finite ( φ A)-Hausdorff measure for X([0, 1]^N) and GrX([0, 1]N). 相似文献
13.
We investigate the adjoints of linear fractional composition operators Cφ acting on classical Dirichlet space D(BN ) in the unit ball BN of CN , and characterize the normality and essential normality of Cφ on D(BN ) and the Dirichlet space modulo constant function D0(BN ), where φ is a linear fractional map of BN . In addition, we also show that for any non-elliptic linear fractional map φ of BN , the composition maps σ ο φ and φ ο σ are elliptic or parabolic linear fractional maps of BN . 相似文献
14.
Saharon Shelah 《Israel Journal of Mathematics》2012,191(2):507-543
We force 2 λ to be large, and for many pairs in the interval (λ, 2 λ ) a strong version of the polarized partition relations holds. We apply this to problems in general topology. For example, consistently, every 2 λ is the successor of a singular and for every Hausdorff regular space X, hd(X) ≤ s(X)+3, hL(X) ≤ s(X)+3 and better when s(X) is regular, via a halfgraph partition relations. For the case s(X) = ℵ 0 we get hd(X), hL(X) ≤ N 2. 相似文献
15.
We investigate the semigroups of full and partial transformations of a set X which preserve a binary relation σ defined on X. We consider in detail the case where σ is an order or a quasi-order relation. There are conditions of regularity of such semigroups. We introduce two definitions
of preservation of σ for the semigroup of binary relations. It is proved that subsets of B(X) preserving σ are semigroups in each case. We give the condition of regularity of B
σ
(X) in the case where σ(X) is a quasi-order. 相似文献
16.
Beurling-Landau-type theorems for non-uniform sampling in shift invariant spline spaces 总被引:1,自引:0,他引:1
Under the appropriate definition of sampling density Dϕ, a function f that belongs to a shift invariant space can be reconstructed in a stable way from its non-uniform samples only
if Dϕ≥1. This result is similar to Landau's result for the Paley-Wiener space B
1/2
. If the shift invariant space consists of polynomial splines, then we show that Dϕ<1 is sufficient for the stable reconstruction of a function f from its samples, a result similar to Beurling's special case
B
1/2
. 相似文献
17.
A directed triple system of order v with index λ, briefly by DTS(v,λ), is a pair (X, B) where X is a v-set and B is a collection of transitive triples (blocks) on X such that every ordered pair of X belongs to λ blocks of B. A simple DTS(v, λ) is a DTS(v, λ) without repeated blocks. A simple DTS(v, ),) is called pure and denoted by PDTS(v, λ) if (x, y, z) ∈ B implies (z, y, x), (z, x, y), (y, x, z), (y, z, x), (x, z, y) B. A large set of disjoint PDTS(v, λ), denoted by LPDTS(v, λ), is a collection of 3(v - 2)/λ disjoint pure directed triple systems on X. In this paper, some results about the existence for LPDTS(v, λ) are presented. Especially, we determine the spectrum of LPDTS(v, 2). 相似文献
18.
M. F. Gamal' 《Journal of Mathematical Sciences》1998,92(1):3589-3596
Let B be a Blaschke product with simple zeros in the unit disk, let Λ be the set of its zeros, and let ϕ∈H∞. It is known that ϕ+BH∞ is a weak* generator of the algebra H∞/BH∞ if (for B that satisfy the Carleson condition (C)) and only if the sequence ϕ(Λ) is a weak* generator of the algebra l∞. In this paper, we show that for any Blaschke product B with simple zeros that does not satisfy condition (C), there exists
B=B1·…·BN, where N ∈ℕ, and B1, …, BN are Blaschke products satisfying condition (C), there exists a function ϕ∈H∞ such that ϕ(Λ) is a weak* generator of the algebra l∞, and ϕ+BH∞ is not a weak* generator of the algebra H∞/BH∞. Bibliography: 12 titles.
Translated fromZapiski Nauchnykh Seminarov POMI, Vol. 232, 1996, pp. 73–85.
Translated by M. F. Gamal'. 相似文献
19.
20.
A covering p from a Cayley graph Cay(G, X) onto another Cay(H, Y) is called typical Frobenius if G is a Frobenius group with H as a Frobenius complement and the map p : G →H is a group epimorphism. In this paper, we emphasize on the typical Frobenius coverings of Cay(H, Y). We show that any typical Frobenius covering Cay(G, X) of Cay(H, Y) can be derived from an epimorphism /from G to H which is determined by an automorphism f of H. If Cay(G, X1) and Cay(G, X2) are two isomorphic typical Frobenius coverings under a graph isomorphism Ф, some properties satisfied by Фare given. 相似文献