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1.
We consider the following singularly perturbed boundary-value problem:
on the interval 0 ≤x ≤ 1. We study the existence and uniqueness of its solutionu(x, ε) having the following properties:u(x, ε) →u 0(x) asε → 0 uniformly inx ε [0, 1], whereu 0(x) εC [0, 1] is a solution of the degenerate equationf(x, u, u′)=0; there exists a pointx 0 ε (0, 1) such thata(x 0)=0,a′(x 0) > 0,a(x) < 0 for 0 ≤x <x 0, anda(x) > 0 forx 0 <x ≤ 1, wherea(x)=f′ v(x,u 0(x),u′ 0(x)). Translated fromMatematicheskie Zametki, Vol. 67, No. 4, pp. 520–524, April, 2000.  相似文献   

2.
This paper is concerned with a class of neutral difference equations of second order with positive and negative coefficients of the forms
where τ, δ and σ are nonnegative integers and {p n }, {q n } and {c n } are nonnegative real sequences. Sufficient conditions for oscillation of the equations are obtained. Research of the first author was supported by Department of Science and Technology, New Delhi, Govt. of India, under BOYSCAST Programme vide Sanc. No. 100/IFD/5071/2004-2005 Dated 04.01.2005.  相似文献   

3.
Let Un be the unit polydisc of Cn and φ= (φ1,...,φn? a holomorphic self-map of Un. Let 0≤α< 1. This paper shows that the composition operator Cφ, is bounded on the Lipschitz space Lipa(Un) if and only if there exists M > 0 such thatfor z∈Un. Moreover Cφ is compact on Lipa(Un) if and only if Cφ is bounded on Lipa(Un) and for every ε > 0, there exists a δ > 0 such that whenever dist(φ(z),σUn) <δ  相似文献   

4.
In this paper, we consider the following Reinhardt domains. Let M = (M1, M2,..., Mn) : [0,1] → [0,1]^n be a C2-function and Mj(0) = 0, Mj(1) = 1, Mj″ 〉 0, C1jr^pj-1 〈 Mj′(r) 〈 C2jr^pj-1, r∈ (0, 1), pj 〉 2, 1 ≤ j ≤ n, 0 〈 C1j 〈 C2j be constants. Define
DM={z=(z1,z2,…,Zn)^T∈C^n:n∑j=1 Mj(|zj|)〈1}
Then DM C^n is a convex Reinhardt domain. We give an extension theorem for a normalized biholomorphic convex mapping f : DM -→ C^n.  相似文献   

5.
Abstract. Without the Lipschitz assumption and boundedness of K in arbitrary Banach spaces,the Ishikawa iteration  相似文献   

6.
We use viscosity approximation methods to obtain strong convergence to common fixed points of monotone mappings and a countable family of nonexpansive mappings. Let C be a nonempty closed convex subset of a Hilbert space H and P C is a metric projection. We consider the iteration process {x n } of C defined by x 1 = xC is arbitrary and
$ x_{n + 1} = \alpha _n f(x_n ) + (1 - \alpha _n )S_n P_C (x_n + \lambda _n Ax_n ) $ x_{n + 1} = \alpha _n f(x_n ) + (1 - \alpha _n )S_n P_C (x_n + \lambda _n Ax_n )   相似文献   

7.
We analyze polynomials P n that are biorthogonal to exponentials , in the sense that
Here α>−1. We show that the zero distribution of P n as n→∞ is closely related to that of the associated exponent polynomial
More precisely, we show that the zero counting measures of {P n (−4nx)} n=1 converge weakly if and only if the zero counting measures of {Q n } n=1 converge weakly. A key step is relating the zero distribution of such a polynomial to that of the composite polynomial
under appropriate assumptions on {Δ n,j }.   相似文献   

8.
Let Sk(Γ) be the space of holomorphic Γ-cusp forms f(z) of even weight k ≥ 12 for Γ = SL(2, ), and let Sk(Γ)+ be the set of all Hecke eigenforms from this space with the first Fourier coefficient af(1) = 1. For f ∈ Sk(Γ)+, consider the Hecke L-function L(s, f). Let
It is proved that for large K,
where ε > 0 is arbitrary. For f ∈ Sk(Γ)+, let L(s, sym 2 f) denote the symmetric square L-function. It is proved that as k → ∞ the frequence
converges to a distribution function G(x) at every point of continuity of the latter, and for the corresponding characteristic function an explicit expression is obtained. Bibliography: 17 titles. __________ Translated from Zapiski Nauchnykh Seminarov POMI, Vol. 314, 2004, pp. 221–246.  相似文献   

9.
Let L n a (x), n=0,1,…, be the Laguerre polynomials of order a>−1. Denote n a (x)=(n!/Γ(n+a+1))1/2 L n a (x)e x/2. Let
be the kernel of the semigroup {T t } t>0 associated with the system n a considered on ((0,∞),x a dx). We say that a function f belongs to the Hardy space H 1 associated with the semigroup if the maximal function
belongs to L 1((0,∞),x a dx). We prove a special atomic decomposition of the elements of the Hardy space. Research supported by the European Commission Marie Curie Host Fellowship for the Transfer of Knowledge “Harmonic Analysis, Nonlinear Analysis and Probability” MTKD-CT-2004-013389, and by Polish funds for science in the years 2005–2008 (research project 1P03A03029).  相似文献   

10.
Let E be a uniformly convex Banach space and K a nonempty convex closed subset which is also a nonexpansive retract of E. Let T 1, T 2 and T 3: KE be asymptotically nonexpansive mappings with {k n }, {l n } and {j n }. [1, ∞) such that Σ n=1 (k n − 1) < ∞, Σ n=1 (l n − 1) < ∞ and Σ n=1 (j n − 1) < ∞, respectively and F nonempty, where F = {xK: T 1x = T 2x = T 3 x} = x} denotes the common fixed points set of T 1, T 2 and T 3. Let {α n }, {α′ n } and {α″ n } be real sequences in (0, 1) and ≤ {α n }, {α′ n }, {α″ n } ≤ 1 − for all nN and some > 0. Starting from arbitrary x 1K define the sequence {x n } by
(i) If the dual E* of E has the Kadec-Klee property then {x n } converges weakly to a common fixed point pF; (ii) If T satisfies condition (A′) then {x n } converges strongly to a common fixed point pF.   相似文献   

11.
Let {X n } n ≥0 be a Harris recurrent Markov chain with state space E and invariant measure π. The law of the iterated logarithm and the law of weak convergence are given for the additive functionals of the form
where ƒ is a real π-centered function defined on E. Some similar results are also obtained for additive functionals which are martingales associated with {X n } n ≥0. Received: 15 September 1998 / Revised version: 1 April 1999  相似文献   

12.
Let f(z) be a holomorphic Hecke eigenform of weight k with respect to SL(2, ) and let
denote the symmetric square L-function of f. A Voronoi type formula for
and the relation
are proved. Heuristic approaches to estimation of exponential sums arising in this connection are considered. Bibliography: 9 titles. __________ Translated from Zapiski Nauchnykh Seminarov POMI, Vol. 314, 2004, pp. 247–256.  相似文献   

13.
We study the expansion of derivatives along orbits of real and complex one-dimensional mapsf, whose Julia setJ f attracts a finite setCrit of non-flat critical points. Assuming that for eachcεCrit, either |D f n(f(c))|→∞ (iff is real) orb n·|Df n(f(c))|→∞ for some summable sequence {b n} (iff is complex; this is equivalent to summability of |D f n(f(c))|−1), we show that for everyxεJ f\U i f −i(Crit), there exist(x)≤max c (c) andK′(x)>0
for infinitely manyn. Here 0=n s<…<n 1<n 0=n are so-called critical times,c i is a point inCrit (or a repelling periodic point in the boundary of the immediate basin of a hyperbolic periodic attractor), which shadows orb(x) forn i−ni +1 iterates, and
, for uniform constantsK>0 and λ>1. If allcεCrit have the same critical order, thenK′(x) is uniformly bounded away from 0. Several corollaries are derived. In the complex case, eitherJ f= orJ f has zero Lebesgue measure. Also (assuming all critical points have the same order) there existk>0 such that ifn is the smallest integer such thatx enters a certain critical neighbourhood, then |Df n(x)|≥k. The original paper used an incorrect version of the Koebe Lemma cited from [21] as was pointed out by the referee and Genadi Levin in the autumn of 2001. The corrected version of November 2001 only uses the classical Koebe Lemma. Apparently, all results in Feliks Przytycki’s paper [21] go through using the classical Koebe Lemma instead of his Lemma 1.2. Both authors gratefully acknowledge the support of the PRODYN program of the European Science Foundation. HB was partially supported by a fellowship of The Royal Netherlands Academy of Arts and Sciences (KNAW). SvS was partially supported by GR/M82714/01.  相似文献   

14.
 Let K be a field of characteristic 0 and let p, q, G 0 , G 1 , P ∈K[x], deg P ⩾ 1. Further, let the sequence of polynomials (G n (x)) n=0 be defined by the second order linear recurring sequence
In this paper we give conditions under which the diophantine equation G n (x) = G m (P(x)) has at most exp(1018) many solutions (n, m) ε ℤ2, n, m ⩾ 0. The proof uses a very recent result on S-unit equations over fields of characteristic 0 due to Evertse, Schlickewei and Schmidt [14]. Under the same conditions we present also bounds for the cardinality of the set
  相似文献   

15.
Let X 1, X 2, ... be i.i.d. random variables. The sample range is R n = max {X i , 1 ≤ i ≤ n} − min {X i , 1 ≤ i ≤ n}. If for a non-degenerate distribution G and some sequences (α k ), (β k ) then we have
and
almost surely for any continuity point x of G and for any bounded Lipschitz function f: R → R.   相似文献   

16.
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   

17.
The equations under consideration have the following structure:
where 0 < x n < ∞, (x 1, …, x n−1) ∈ Ω, Ω is a bounded Lipschitz domain, is a function that is continuous and monotonic with respect to u, and all coefficients are bounded measurable functions. Asymptotic formulas are established for solutions of such equations as x n → + ∞; the solutions are assumed to satisfy zero Dirichlet or Neumann boundary conditions on ∂Ω. Previously, such formulas were obtained in the case of a ij, ai depending only on (x 1, …, x n−1). __________ Translated from Trudy Seminara imeni I. G. Petrovskogo, No. 25, pp. 98–111, 2005.  相似文献   

18.
Let f(x, y) be a periodic function defined on the region D
with period 2π for each variable. If f(x, y) ∈ C p (D), i.e., f(x, y) has continuous partial derivatives of order p on D, then we denote by ω α,β(ρ) the modulus of continuity of the function
and write
For p = 0, we write simply C(D) and ω(ρ) instead of C 0(D) and ω 0(ρ). Let T(x,y) be a trigonometrical polynomial written in the complex form
We consider R = max(m 2 + n 2)1/2 as the degree of T(x, y), and write T R(x, y) for the trigonometrical polynomial of degree ⩾ R. Our main purpose is to find the trigonometrical polynomial T R(x, y) for a given f(x, y) of a certain class of functions such that
attains the same order of accuracy as the best approximation of f(x, y). Let the Fourier series of f(x, y) ∈ C(D) be
and let
Our results are as follows Theorem 1 Let f(x, y) ∈ C p(D (p = 0, 1) and
Then
holds uniformly on D. If we consider the circular mean of the Riesz sum S R δ (x, y) ≡ S R δ (x, y; f):
then we have the following Theorem 2 If f(x, y) ∈ C p (D) and ω p(ρ) = O(ρ α (0 < α ⩾ 1; p = 0, 1), then
holds uniformly on D, where λ 0 is a positive root of the Bessel function J 0(x) It should be noted that either
or
implies that f(x, y) ≡ const. Now we consider the following trigonometrical polynomial
Then we have Theorem 3 If f(x, y) ∈ C p(D), then uniformly on D,
Theorems 1 and 2 include the results of Chandrasekharan and Minakshisundarm, and Theorem 3 is a generalization of a theorem of Zygmund, which can be extended to the multiple case as follows Theorem 3′ Let f(x 1, ..., x n) ≡ f(P) ∈ C p and let
where
and
being the Fourier coefficients of f(P). Then
holds uniformly. __________ Translated from Acta Scientiarum Naturalium Universitatis Pekinensis, 1956, (4): 411–428 by PENG Lizhong.  相似文献   

19.
Let u=u(x,t,uo)represent the global solution of the initial value problem for the one-dimensional fluid dynamics equation ut-εuxxt+δux+γHuxx+βuxxx+f(u)x=αuxx,u(x,0)=uo(x), whereα〉0,β〉0,γ〉0,δ〉0 andε〉0 are constants.This equation may be viewed as a one-dimensional reduction of n-dimensional incompressible Navier-Stokes equations. The nonlinear function satisfies the conditions f(0)=0,|f(u)|→∞as |u|→∞,and f∈C^1(R),and there exist the following limits Lo=lim sup/u→o f(u)/u^3 and L∞=lim sup/u→∞ f(u)/u^5 Suppose that the initial function u0∈L^I(R)∩H^2(R).By using energy estimates,Fourier transform,Plancherel's identity,upper limit estimate,lower limit estimate and the results of the linear problem vt-εv(xxt)+δvx+γHv(xx)+βv(xxx)=αv(xx),v(x,0)=vo(x), the author justifies the following limits(with sharp rates of decay) lim t→∞[(1+t)^(m+1/2)∫|uxm(x,t)|^2dx]=1/2π(π/2α)^(1/2)m!!/(4α)^m[∫R uo(x)dx]^2, if∫R uo(x)dx≠0, where 0!!=1,1!!=1 and m!!=1·3…(2m-3)…(2m-1).Moreover lim t→∞[(1+t)^(m+3/2)∫R|uxm(x,t)|^2dx]=1/2π(x/2α)^(1/2)(m+1)!!/(4α)^(m+1)[∫Rρo(x)dx]^2, if the initial function uo(x)=ρo′(x),for some functionρo∈C^1(R)∩L^1(R)and∫Rρo(x)dx≠0.  相似文献   

20.
In this contribution we analyze the generating functions for polynomials orthogonal with respect to a symmetric linear functional u, i.e., a linear application in the linear space of polynomials with complex coefficients such that . In some cases we can deduce explicitly the expression for the generating function
where {Pn}n is the sequence of orthogonal polynomials with respect to u. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   

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