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1.
We prove that the G-invariant orbital measures supported on adjoint orbits in the Lie algebra of a classical, compact, connected, simple Lie group satisfy a smoothness dichotomy: Either μ k is singular to Lebesgue measure or μ k L 2. The minimum k for which μ k L 2 is specified and is also the minimum k such that the k-fold sum of the orbit has positive measure. S. K. Gupta appreciates the hospitality of the Department of Pure Mathematics at the University of Waterloo where some of this research was done. K. E. Hare was supported in part by NSERC.  相似文献   

2.
In this paper, we prove that the 2D Navier-Stokes equations possess a global attractor in Hk(Ω,R2) for any k ≥ 1, which attracts any bounded set of Hk(Ω,R2) in the H^k-norm. The result is established by means of an iteration technique and regularity estimates for the linear semigroup of operator, together with a classical existence theorem of global attractor. This extends Ma, Wang and Zhong's conclusion.  相似文献   

3.
A graph is called symmetric if its automorphism group acts transitively on its arc set. In this paper, we classify all connected cubic symmetric graphs of order 16p 2 for each prime p.  相似文献   

4.
The classical Hardy-Littlewood-Sobolev theorems for Riesz potentials (−Δ)−α/2 are extended to the generalised fractional integrals L –α/2 for 0 < α < n, where L=−div A∇ is a uniformly complex elliptic operator with bounded measurable coefficients in ℝn.  相似文献   

5.
We show that meromorphic solutions f, g of f 2 + g 2 = 1 in C2 must be constant, if f z2 and g z1 have the same zeros (counting multiplicities). We also apply the result to characterize meromorphic solutions of certain nonlinear partial differential equations.  相似文献   

6.
Let ( Y,d,dl )\left( {\mathcal{Y},d,d\lambda } \right) be (ℝ n , |·|, μ), where |·| is the Euclidean distance, μ is a nonnegative Radon measure on ℝ n satisfying the polynomial growth condition, or the Gauss measure metric space (ℝ n , |·|, d λ ), or the space (S, d, ρ), where S ≡ ℝ n ⋉ ℝ+ is the (ax + b)-group, d is the left-invariant Riemannian metric and ρ is the right Haar measure on S with exponential growth. In this paper, the authors introduce and establish some properties of the atomic Hardy-type spaces { Xs ( Y ) }0 < s \leqslant ¥\left\{ {X_s \left( \mathcal{Y} \right)} \right\}_{0 < s \leqslant \infty } and the BMO-type spaces { BMO( Y, s ) }0 < s \leqslant ¥\left\{ {BMO\left( {\mathcal{Y}, s} \right)} \right\}_{0 < s \leqslant \infty }. Let H 1 ( Y )\left( \mathcal{Y} \right) be the known atomic Hardy space and L 01 ( Y )\left( \mathcal{Y} \right) the subspace of fL 1 ( Y )\left( \mathcal{Y} \right) with integral 0. The authors prove that the dual space of X s ( Y )\left( \mathcal{Y} \right) is BMO( Y,s )BMO\left( {\mathcal{Y},s} \right) when s ∈ (0,∞), X s ( Y )\left( \mathcal{Y} \right) = H 1 ( Y )\left( \mathcal{Y} \right) when s ∈ (0, 1], and X ( Y )\left( \mathcal{Y} \right) = L 01 ( Y )\left( \mathcal{Y} \right) (or L 1 ( Y )\left( \mathcal{Y} \right)). As applications, the authors show that if T is a linear operator bounded from H 1 ( Y )\left( \mathcal{Y} \right) to L 1 ( Y )\left( \mathcal{Y} \right) and from L 1 ( Y )\left( \mathcal{Y} \right) to L 1,∞ ( Y )\left( \mathcal{Y} \right), then for all r ∈ (1,∞) and s ∈ (r,∞], T is bounded from X r ( Y )\left( \mathcal{Y} \right) to the Lorentz space L 1,s ( Y )\left( \mathcal{Y} \right), which applies to the Calderón-Zygmund operator on (ℝ n , |·|, μ), the imaginary powers of the Ornstein-Uhlenbeck operator on (ℝ n , |·|, d γ ) and the spectral operator associated with the spectral multiplier on (S, d, ρ). All these results generalize the corresponding results of Sweezy, Abu-Shammala and Torchinsky on Euclidean spaces.  相似文献   

7.
We introduce the notion of L 2-rigidity for von Neumann algebras, a generalization of property (T) which can be viewed as an analogue for the vanishing of 1-cohomology into the left regular representation of a group. We show that L 2-rigidity passes to normalizers and is satisfied by nonamenable II1 factors which are non-prime, have property Γ, or are weakly rigid. As a consequence we obtain that if M is a free product of diffuse von Neumann algebras, or if M=LΓ where Γ is a finitely generated group with β1 (2)(Γ)>0, then any nonamenable regular subfactor of M is prime and does not have properties Γ or (T). In particular this gives a new approach for showing solidity for a free group factor thus recovering a well known recent result of N. Ozawa.  相似文献   

8.
Much of the recent literature on risk measures is concerned with essentially bounded risks in L . In this paper we investigate in detail continuity and representation properties of convex risk measures on L p spaces. This frame for risks is natural from the point of view of applications since risks are typically modelled by unbounded random variables. The various continuity properties of risk measures can be interpreted as robustness properties and are useful tools for approximations. As particular examples of risk measures on L p we discuss the expected shortfall and the shortfall risk. In the final part of the paper we consider the optimal risk allocation problem for L p risks.  相似文献   

9.
Let R be a real AW *-algebra, and suppose that its complexification M = R + iR is also a (complex) AW *-algebra. We prove that R is of type I if and only if so is M.Translated from Funktsionalnyi Analiz i Ego Prilozheniya, Vol. 38, No. 4, pp. 79–81, 2004Original Russian Text Copyright © by Sh. A. Ayupov  相似文献   

10.
We study the word problem for the free Burnside semigroups satisfying x 2 = x 3. For any k > 2, we reduce this problem for the k-generated free Burnside semigroup B(2, 1, k) to the word problem for the two-generated semigroup B(2, 1, 2). Furthermore, if every element of B(2, 1, 2) is a regular language, then every element of B(2, 1, k) appears to be a regular language as well. Thus, Brzozowski’s conjecture holds for the semigroup B(2, 1, k) if and only if it holds for B(2, 1, 2).  相似文献   

11.
We show that if U* is a hypercover of a topological space X then the natural map hocolim U* X is a weak equivalence. This fact is used to construct topological realization functors for the 1-homotopy theory of schemes over real and complex fields. In an appendix, we also prove a theorem about computing homotopy colimits of spaces that are not cofibrant.Mathematics Subject Classification (2000):55U35, 14F20, 14F42The second author was supported by an NSF Postdoctoral Research Fellowship  相似文献   

12.
Let Λ be an isolated non-trivial transitive set of a C 1 generic diffeomorphism f ∈ Diff (M ). We show that the space of invariant measures supported on Λ coincides with the space of accumulation measures of time averages on one orbit. Moreover, the set of points having this property is residual in Λ (which implies that the set of irregular+ points is also residual in Λ). As an application, we show that the non-uniform hyperbolicity of irregular+ points in Λ with totally 0 measure (resp., the non-uniform hyperbolicity of a generic subset in Λ) determines the uniform hyperbolicity of Λ.  相似文献   

13.
We confirm a twenty year old conjecture by showing that a nonzero prime ideal P in the algebra H of bounded analytic functions in the open unit disk is countably generated if and only if it is either a principal ideal generated by the polynomial zz0, |z0|<1, or if P is generated by the n-th roots of an atomic inner function. The case of the algebra H+C is also dealt with. Dedicated to the 70th birthday of Joseph Cima Research supported by the RIP-program Oberwolfach 2004.  相似文献   

14.
We prove an L~∞ version of the Yan theorem and deduce from it a necessary condition for theabsence of free lunches in a model of financial markets,in which asset prices are a continuous R~d valued processand only simple investment strategies are admissible.Our proof is based on a new separation theorem for convexsets of finitely additive measures.  相似文献   

15.
We study the Cauchy problem for time-dependent diffusion operators with singular coefficients on L1-spaces induced by infinitesimal invariant measures. We give sufficient conditions on the coefficients such that the Cauchy-Problem is well-posed. We construct associated diffusion processes with the help of the theory of generalized Dirichlet forms. We apply our results in particular to construct a large class of Nelson-diffusions that could not been constructed before.  相似文献   

16.
A closed topological n-manifold M n is of S 1-category 2 if it can be covered by two open subsets W 1,W 2 such that the inclusions W i M n factor homotopically through maps W i S 1M n . We show that the fundamental group of such an n-manifold is a cyclic group or a free product of two cyclic groups with nontrivial amalgamation. In particular, if n = 3, the fundamental group is cyclic.   相似文献   

17.
We point out that if the Hardy–Littlewood maximal operator is bounded on the space L p(t)(ℝ), 1 < ap(t) ≤ b < ∞, t ∈ ℝ, then the well-known characterization of the spaces L p (ℝ), 1 < p < ∞, by the Littlewood–Paley theory extends to the space L p(t)(ℝ). We show that, for n > 1 , the Littlewood–Paley operator is bounded on L p(t) (ℝ n ), 1 < ap(t) ≤ b < ∞, t ∈ ℝ n , if and only if p(t) = const. Published in Ukrains’kyi Matematychnyi Zhurnal, Vol. 60, No. 12, pp. 1709–1715, December, 2008.  相似文献   

18.
Let Γ ⊂ ℝn, n ≥ 2, be the boundary of a bounded domain. We prove that the translates by elements of Γ of functions which transform according to a fixed irreducible representation of the orthogonal group form a dense class in L p (ℝn) for . A similar problem for noncompact symmetric spaces of rank one is also considered. We also study the connection of the above problem with the injectivity sets for weighted spherical mean operators. The first author was supported in part by a grant from UGC via DSA-SAP Phase IV.  相似文献   

19.
We use a new method to study arrangement in CP l , define a class of nice point arrangements and show that if two nice point arrangements have the same combinatorics, then their complements are diffeomorphic to each other. In particular, the moduli space of nice point arrangements with same combinatorics in CP l is connected. It generalizes the result on point arrangements in CP 3 to point arrangements in CP l for any l.  相似文献   

20.
An undirected graph without isolated vertices is said to be semisymmetric if its full automorphism group acts transitively on its edge set but not on its vertex set. In this paper, we inquire the existence of connected semisymmetric cubic graphs of order 16p 2. It is shown that for every odd prime p, there exists a semisymmetric cubic graph of order 16p 2 and its structure is explicitly specified by giving the corresponding voltage rules generating the covering projections.  相似文献   

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