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991.
We prove the existence of positive symmetric solutions to the semilinear elliptic problem
in both the radial case N = k ≥ 3 and the cylindrical case N ≥ k + 3 ≥ 6. The potential V is measurable, positive and it is only required to satisfy a mild integrability condition. The nonlinearity is continuous and has a doublepower behavior, super-critical near the origin and sub-critical at infinity. If f is odd, we show that the radial problem has infinitely many solutions. In proving these results we exploit the compactness of suitable restrictions of the embedding Supported by MIUR, project “Variational Methods and Nonlinear Differential Equations”.  相似文献   
992.
In this paper, we consider the following second-order three-point boundary value problem
where f : [0, 1] × R2 R is continuous, > 0, 0 < < 1 such that < 1. We give conditions on f and two pairs of lower and upper solutions to ensure the existence of at least three solutions of the given problem. Our method is based upon Leray-Schauder degree theory. The emphasis here is that f depends on the first derivative. Our results extend some results in the references.Received: 17 June 2004  相似文献   
993.
Let be a weighted space with weight . In this paper we show that for every Wiener-Hopf operator T on and for every a I, there exists a function such that
for all Here (g)a denotes the function x g(x)eax for and where R+ is the spectral radius of the shift S : f(x) f(x–1) on while is the spectral radius of the backward shift S–1 : f(x) (P+f)(x+1) on Moreover, there exists a constant C, depending on , such that for every a I. If R < R+, we prove that there exists a bounded holomorphic function v on such that for the function va is the restriction of v on the line Received: 18 May 2004  相似文献   
994.
We investigate spectral properties of integral operators of the form
acting on Banach spaces of analytic functions on the unit disc. In the case that g is a rational function, analytic on the unit disc, we obtain the spectrum, essential spectrum and index of Sg. Finally, we give examples of such operators pertaining to hyponormality. Received: 30 August 2004; revised: 25 January 2005  相似文献   
995.
Let X be a Banach space and let (ξj)j ≧ 1 be an i.i.d. sequence of symmetric random variables with finite moments of all orders. We prove that the following assertions are equivalent:
1.  There exists a constant K such that
for all Lipschitz functions f : X → X satisfying f (0) = 0 and all finite sequences x1, ..., xn in X.
2.  X is isomorphic to a Hilbert space.
Received: 10 January 2005; revised: 5 April 2005  相似文献   
996.
A congruence lattice L of an algebra A is called power-hereditary if every 0-1 sublattice of Ln is the congruence lattice of an algebra on An for all positive integers n. Let A and B be finite algebras. We prove
•  If ConA is distributive, then every subdirect product of ConA and ConB is a congruence lattice on A × B.
•  If ConA is distributive and ConB is power-hereditary, then (ConA) × (ConB) is powerhereditary.
•  If ConA ≅ N5 and ConB is modular, then every subdirect product of ConA and ConB is a congruence lattice.
•  Every congruence lattice representation of N5 is power-hereditary.
Received November 11, 2004; accepted in final form November 23, 2004.  相似文献   
997.
We solve an asymptotic problem in the geometry of numbers, where we count the number of singular n×n matrices where row vectors are primitive and of length at most T. Without the constraint of primitivity, the problem was solved by Y. Katznelson. We show that as T, the number is asymptotic to for n3. The 3-dimensional case is the most problematic and we need to invoke an equidistribution theorem due to W. M. Schmidt.  相似文献   
998.
The continued fractions studied by Tasoev are not widely known although their characteristics are very similar to those of Hurwitz continued fractions. Recently, the author found several general forms of Tasoev continued fractions, and by applying this method he also obtained some more general forms of Hurwitz continued fractions belonging to so called tanh-type and tan-type. In this paper, we constitute a new class of general forms of Hurwitz continued fractions of e-type. The known continued fraction expansions of e1/a (a 1), ae1/a and (1/a)e1/a are included as special cases. The corresponding Tasoev continued fractions are also derived.  相似文献   
999.
In [2], it was shown that if a and b are multiplicatively independent integers and ɛ > 0, then the inequality gcd (an − 1,bn − 1) < exp(ɛn) holds for all but finitely many positive integers n. Here, we generalize the above result. In particular, we show that if f(x),f1(x),g(x),g1(x) are non-zero polynomials with integer coefficients, then for every ɛ > 0, the inequality holds for all but finitely many positive integers n.  相似文献   
1000.
In this paper we consider special elements of the Fock space #x2131; n . That is the space of entire functionsf:ℂ: n →ℂ, such that the followingL 2- condition is satisfied: . Here we show that there exists an entire functiong:ℂ n →ℂ such that for every one-dimensional subspace Π⊂ℂ n and for all 0<∈<2 we have , but in the limit case ∈=0 we have . This result is analogue to a result from [1]. There holomorphic functions on the unit-ball are investigated. Furthermore the proof — as the one in [1] — uses a theorem from [2]. Therefore we give another application of the results from [2] — namely for spaces of entire functions.  相似文献   
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