Asymptotic behavior of the solutions of an integrodifferential system

Summary We consider the system(L): , t ⩾ p, y(t)=f(t), t⩽0, where y is an n-vector and each A_i, B(t) are n × n matrices. System(L) generates a semigroup by means of T_tf(s)=y (t+s, f), f(s) ∈ BC_l(− ∞, 0]. Under some hypotheses concerning the roots ofdet where is the Laplace transform of B(t), the asymptotic behavior of y(t) is discussed. Two typical results are: Theorem 3.1: suppose ∥B(t)∥ ɛ L₁[0, ∞), thendet forRe λ>0 iff for every ɛ>0 there is an M_ɛ>0 such that ∥T_tf∥_l ⩽ ⩽ M_ɛ exp [ɛt]∥f∥_l for t ⩾ 0. Corollary 3.1.1: suppose exp [at]B(t) ∈ ∈ L₁[0, ∞) for some a>0 anddet forRe λ>−a. Then the solution of(L) is exponentially asymptotically stable. Entrata in Redazione il 21 marzo 1975. The author is grateful to ProfessorC. Corduneanu for suggesting this problem and for many helpful discussions during the preparation of the paper.     

The true order of magnitude of Lamé rounding error sums

Let (z ∈ ℝ). Further let λ denote a large real parameter. We show that for arbitrary real numbersk and α withk>=2.7013 and 0<α≦1,

Inequalities of Paley type for noncommutative martingales

Summary The purpose of this paper is to study the validity of the Paley inequality on square function, for noncommutative martingales. Let be a regular gage space, and a sequence of von-Neumann algebras such that we prove that for every , where ɛ_n(F) is the conditional expectation of F with respect to the subalgebra : We also consider the case of a martingale arising in the context of harmonic analysis on noncommutative discrete groups, in analogy to the theorem of R.E.A.C. Paley on Fourier-Walsh series. Entrata in Redazione il 26 gennaio 1977. Partially sponsored by C.N.R.     

Linearization,trace, and determinant of certain meromorphic operator functions

In this paper operator functions of type

Asymptotic behaviour of the phase in non-smooth obstacle scattering

In this paper, we study the asymptotic behaviour of the scattering phases(λ) of the Dirichlet Laplacian associated with obstacle , where Ω is a bounded open subset of ℝ ⁿ (n≥2) with non-smooth boundary ∂Ω and connected complement Ω _e =ℝ ⁿ . We can prove that if Ω satisfies a certain geometrical condition, then

Bounded solutions for 119-01119-01119-01-problem in pseudo-Siegel domains

Summary We study the problem of the existence of bounded solutions for the equation on pseudo-Siegel domains when the data satisfies the condition .

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Sunto Si studia il problema dell'esistenza di soluzioni limitate per l'equazione sui domini pseudo-Siegel quando il dato soddisfa alla condizione .

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Work done within the Project 40% M.U.R.S.T. «Geometria Reale e Complessa».     

Entropies with the branching property

Summary It is proved that every entropy with the property of branching has the form , where J is a compositive information measure under a regular binary operation. In particular all the classical entropies with the branching property such as that of Shannon have the form .

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Sunto Si dimostra che ogni entropia che goda della proprietà di diramazione ha necessariamente la forma dove J è una misura di informazione compositiva con una operazione binaria regolare. In particolare tutte le entropie classiche che godono della proprietà di diramazione quale quella di Shannon hanno la forma .

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Entrata in Redazione il 9 aprile 1973.     

The asymptotic value of the circle-packing rigidity constants s n *

The hexagonal circle-packing rigidity constantss _n are known to satisfys _n =O(1/n). In this paper it is shown that

An interesting result for positive series

For arbitrary given positive term series and , the present paper provides an interesting necessary and sufficient condition for . In Memory of Professor M. T. Cheng The Research Project of the Mathematical Institute, Ningbo University. Supported in part by Zhejiang Provincial Natural Science Foundation, and by State Key Laboratory of Southwest Institute of Petroleum.     

Regolarità hölderiana delle derivate dei minimi di funzionali con parte principale quadratica

Riassunto In questo lavoro si prova la regolarità h?lderiana delle derivate, fino all'ordinek, dei minimi locali dei funzionali sotto opportune ipotesi suA _ij ^αβ e sug.

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Summary In this paper we prove h?lder-continuity of the derivates, up to orderk, of local minima of functionals under suitable hypotheses forA _ij ^αβ andg.

     

Characterization of certain classes of orthogonal polynomials related to elliptic functions

Summary In this paper we determine all orthogonal polynomials U_n(x) such that U_n(x)=x^−1/2 F _2n+1 (x ^1/2 ) and where f(t), u(t) have Taylor series expansions. Supported in part by N. S. F. grant GP-1593.     

Estimate of fourier transforms with respect to the system of generalized eigenfunctions of the Schrödinger operator with Stummel-type potential

Suppose thatА is a nonnegative self-adjoint extension to { } of the formal differential operator−Δu+q(x)u with potentialq(x) satisfying the condition {

Tensor sequences and inductive limits with local partition of unity

In this note we characterize those locally convex hulls for which the -tensor product is topologically isomorphic to the locally convex hull for all normed spaces E. By using -sequences in the sense of W.Kaballo and D.Vogt [18] it is shown that is commutable with -tensor products if and only if F admits a local partition of unity. In this paper we give examples of locally convex hulls with local partition of unity. From this one obtains conditions under which the -tensor product of two bornological (DF)-spaces is again a bornological (DF)-space. Applications to sequence spaces are given.     

Integration of a zonal function related to the local harmonic analysis on spheres

In studying local harmonic analysis on the sphere Sⁿ, R.S. Strichartz introduced certain zonal functions ϕ₂(d(x, y)) which satisfy the equation , where Δ_z is the Laplace operator and δ_−y the Dirac measure. The explicit expression of the constant a (λ) is given by R.S. Strichartz in the case that n is odd. Appyling the Apéry identity, we show in this paper that for n even, where w_n-1 is the surface area of S^n-1, . The author's research was supported by a grant from NSFC.     

On PC Ansatzs

The paper is devoted to a detailed consideration of an ansatz known from the seventies:

Differential equations of infinite order for orthogonal polynomials

Summary Differential equations of infinite order of the form , where M_k is a polynomial of degree ≦k, have polynomial solutions for suitable values of λ. Necessary and sufficient conditions are given in order that these solutions form a set of orthogonal polynomials. The cases where { degree M_k }=1 and 2 are studied in detail. Supported by N.S.F. Grant GP-5311.     

Strong consistency of nearest neighbor kernel regression estimation for stationary dependent samples

Under quite mild conditions onk _n . the strong consistency is proved for the nearest neighbor density, the nearest neighbor kernel regression and the modified nearest neighbor kernel regression of an a-mixing stationary sequence in time series context. The condition imposed on the mixing coefficients is , . which is simple and weak.     

Estimates for eigenvalues of Laplacian operator with any order

Let D be a bounded domain in an n-dimensional Euclidean space Rn. Assume that 0 ＜ λ1 ≤λ2 ≤ … ≤ λκ ≤ … are the eigenvalues of the Dirichlet Laplacian operator with any order l{(-△)lu=λu, in D u=(δ)u/(δ)(→n)=…(δ)l-1u/(δ)(→n)l-1=0,on (δ)D.Then we obtain an upper bound of the (k 1)-th eigenvalue λκ 1 in terms of the first k eigenvalues.k∑i=1(λκ 1-λi) ≤ 1/n[4l(n 2l-2)]1/2{k∑i=1(λκ 1-λi)1/2λil-1/l k∑i=1(λκ 1-λi)1/2λ1/li}1/2.This ineguality is independent of the domain D. Furthermore, for any l ≥ 3 the above inequality is better than all the known results. Our rusults are the natural generalization of inequalities corresponding to the case l = 2 considered by Qing-Ming Cheng and Hong-Cang Yang. When l = 1, our inequalities imply a weaker form of Yang inequalities. We aslo reprove an implication claimed by Cheng and Yang.     

Representation of analytic functions by generalized series of exponents in unbounded convex domains

We establish conditions for the representation of functions f(z) analytic in unbounded convex domains D and continuous in via series of the form . Translated from Ukrainskii Matematicheskii Zhurnal, Vol. 50, No. 6, pp. 812–817, June, 1998.     

Structure of bounded solutions for a class of abstract differential equations

Summary The paper is concerned with bounded solutions of an equationu′(t)=Bu(t) in Hilbert spaces, . A representation formula is obtained depending on the zeros of Rez(θ).

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Riassunto è studiata la struttura delle soluzioni limitate di una equazione differenzialeu′(t)=Bu(t) in uno spazio di Hilbert, ove , in funzione dei zeri di Rez(θ).

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This research is supported through a grant of the National Research Council Canada.