共查询到20条相似文献,搜索用时 654 毫秒
1.
Yuanyuan Liu 《Operations Research Letters》2010,38(3):218-222
Let P be a positive recurrent infinite transition matrix with invariant distribution π and be a truncated and arbitrarily augmented stochastic matrix with invariant distribution (n)π. We investigate the convergence ‖(n)π−π‖→0, as n→∞, and derive a widely applicable sufficient criterion. Moreover, computable bounds on the error ‖(n)π−π‖ are obtained for polynomially and geometrically ergodic chains. The bounds become rather explicit when the chains are stochastically monotone. 相似文献
2.
We consider the focusing energy-critical nonlinear Hartree equation iut+Δu=−(−4|x|∗2|u|)u. We proved that if a maximal-lifespan solution u:I×Rd→C satisfies supt∈I‖∇u(t)‖2<‖∇W‖2, where W is the static solution of the equation, then the maximal-lifespan I=R, moreover, the solution scatters in both time directions. For spherically symmetric initial data, similar result has been obtained in [C. Miao, G. Xu, L. Zhao, Global wellposedness, scattering and blowup for the energy-critical, focusing Hartree equation in the radial case, Colloq. Math., in press]. The argument is an adaptation of the recent work of R. Killip and M. Visan [R. Killip, M. Visan, The focusing energy-critical nonlinear Schrödinger equation in dimensions five and higher, preprint] on energy-critical nonlinear Schrödinger equations. 相似文献
3.
Vladimir Nikiforov 《Journal of Mathematical Analysis and Applications》2008,337(1):739-743
Let A be an n×n complex matrix and r be the maximum size of its principal submatrices with no off-diagonal zero entries. Suppose A has zero main diagonal and x is a unit n-vector. Then, letting ‖A‖ be the Frobenius norm of A, we show that
|〈Ax,x〉|2?(1−1/2r−1/2n)‖A‖2. 相似文献
4.
Omar Hirzallah 《Journal of Mathematical Analysis and Applications》2003,282(2):578-583
It is shown that if A, B, X are Hilbert space operators such that X?γI, for the positive real number γ, and p,q>1 with 1/p+1/q=1, then |A−B|2?p|A|2+q|B|2 with equality if and only if (1−p)A=B and γ||||A−B|2|||?|||p|A|2X+qX|B|2||| for every unitarily invariant norm. Moreover, if in addition A, B are normal and X is any Hilbert-Schmidt operator, then ‖δA,B2(X)‖2?‖p|A|2X+qX|B|2‖2 with equality if and only if (1−p)AX=XB. 相似文献
5.
Pascale Vitse 《Journal of Functional Analysis》2004,210(1):43-72
For Banach space operators T satisfying the Tadmor-Ritt condition ||(zI−T)−1||?C|z−1|−1, |z|>1, we prove that the best-possible constant CT(n) bounding the polynomial calculus for T, ||p(T)||?CT(n)||p||∞, deg(p)?n, behaves (in the worst case) as as n→∞. This result is based on a new free (Carleson type) interpolation theorem for polynomials of a given degree. 相似文献
6.
Marco Cappiello 《Journal of Functional Analysis》2006,237(2):634-654
We show that all eigenfunctions of linear partial differential operators in Rn with polynomial coefficients of Shubin type are extended to entire functions in Cn of finite exponential type 2 and decay like exp(−2|z|) for |z|→∞ in conic neighbourhoods of the form |Imz|?γ|Rez|. We also show that under semilinear polynomial perturbations all nonzero homoclinics keep the super-exponential decay of the above type, whereas a loss of the holomorphicity occurs, namely we show holomorphic extension into a strip {z∈Cn||Imz|?T} for some T>0. The proofs are based on geometrical and perturbative methods in Gelfand-Shilov spaces. The results apply in particular to semilinear Schrödinger equations of the form
(∗) 相似文献
7.
Daniel KörnleinUlrich Kohlenbach 《Nonlinear Analysis: Theory, Methods & Applications》2011,74(16):5253-5267
This paper gives an explicit and effective rate of convergence for an asymptotic regularity result ‖Txn−xn‖→0 due to Chidume and Zegeye in 2004 [14] where (xn) is a certain perturbed Krasnoselski-Mann iteration schema for Lipschitz pseudocontractive self-mappings T of closed and convex subsets of a real Banach space. We also give a qualitative strengthening of the theorem by Chidume and Zegeye, by weakening the assumption of the existence of a fixed point. For the bounded case, our bound is polynomial in the data involved. 相似文献
8.
We study blow-up of radially symmetric solutions of the nonlinear heat equation ut=Δu+|u|p−1u either on RN or on a finite ball under the Dirichlet boundary conditions. We assume and that the initial data is bounded, possibly sign-changing. Our first goal is to establish various characterizations of type I and type II blow-ups. Among many other things we show that the following conditions are equivalent: (a) the blow-up is of type II; (b) the rescaled solution w(y,s) converges to either φ∗(y) or −φ∗(y) as s→∞, where φ∗ denotes the singular stationary solution; (c) u(x,T)/φ∗(x) tends to ±1 as x→0, where T is the blow-up time.Our second goal is to study continuation beyond blow-up. Among other things we show that if a blow-up is of type I and incomplete, then its limit L1 continuation becomes smooth immediately after blow-up, and that type I blow-up implies “type I regularization,” that is, (t−T)1/(p−1)‖u(⋅,t)L∞‖ is bounded as t↘T. We also give various criteria for complete and incomplete blow-ups. 相似文献
9.
Minkyun Kim C.J. Neugebauer 《Journal of Mathematical Analysis and Applications》2002,275(2):575-585
We introduce a bound M of f, ‖f‖∞?M?2‖f‖∞, which allows us to give for 0?p<∞ sharp upper bounds, and for −∞<p<0 sharp lower bounds for the average of |f|p over E if the average of f over E is zero. As an application we give a new proof of Grüss's inequality estimating the covariance of two random variables. We also give a new estimate for the error term in the trapezoidal rule. 相似文献
10.
11.
Antonio Russo 《Journal of Differential Equations》2011,251(9):2387-2408
The Navier problem is to find a solution of the steady-state Navier-Stokes equations such that the normal component of the velocity and a linear combination of the tangential components of the velocity and the traction assume prescribed value a and s at the boundary. If Ω is exterior it is required that the velocity converges to an assigned constant vector u0 at infinity. We prove that a solution exists in a bounded domain provided ‖a‖L2(∂Ω) is less than a computable positive constant and is unique if ‖a‖W1/2,2(∂Ω)+‖s‖L2(∂Ω) is suitably small. As far as exterior domains are concerned, we show that a solution exists if ‖a‖L2(∂Ω)+‖a−u0⋅n‖L2(∂Ω) is small. 相似文献
12.
In this paper we determine the automorphism group of the Fock–Bargmann–Hartogs domain Dn,m in Cn×Cm which is defined by the inequality ‖ζ‖2<e−μ‖z‖2. 相似文献
13.
Let ‖·‖ be a norm on the algebra ?n of all n × n matrices over ?. An interesting problem in matrix theory is that “Are there two norms ‖·‖1 and ‖·‖2 on ?n such that ‖A‖ = max|‖Ax‖2: ‖x‖1 = 1} for all A ∈ ?n?” We will investigate this problem and its various aspects and will discuss some conditions under which ‖·‖1 = ‖·‖2. 相似文献
14.
Chen Zhimin 《Arkiv f?r Matematik》1990,28(1-2):371-381
A sharp result on global small solutions to the Cauchy problem $$u_t = \Delta u + f\left( {u,Du,D^2 u,u_t } \right)\left( {t > 0} \right),u\left( 0 \right) = u_0 $$ In Rn is obtained under the the assumption thatf is C1+r forr>2/n and ‖u 0‖C2(R n ) +‖u 0‖W 1 2 (R n ) is small. This implies that the assumption thatf is smooth and ‖u 0 ‖W 1 k (R n )+‖u 0‖W 2 k (R n ) is small fork large enough, made in earlier work, is unnecessary. 相似文献
15.
Removable singularity of the polyharmonic equation 总被引:1,自引:0,他引:1
Shu-Yu Hsu 《Nonlinear Analysis: Theory, Methods & Applications》2010,72(2):624-627
Let x0∈Ω⊂Rn, n≥2, be a domain and let m≥2. We will prove that a solution u of the polyharmonic equation Δmu=0 in Ω?{x0} has a removable singularity at x0 if and only if as |x−x0|→0 for n≥3 and as |x−x0|→0 for n=2. For m≥2 we will also prove that u has a removable singularity at x0 if |u(x)|=o(|x−x0|2m−n) as |x−x0|→0 for n≥3 and |u(x)|=o(|x−x0|2m−2log(|x−x0|−1)) as |x−x0|→0 for n=2. 相似文献
16.
This paper is concerned with the standing wave for a class of nonlinear Schrödinger equations
iφt+Δφ−2|x|φ+μ|φ|p−1φ+γ|φ|q−1φ=0, 相似文献
17.
Sönke Blunck 《Journal of Functional Analysis》2002,195(2):350-370
We extend the Trotter-Kato-Chernoff theory of strong approximation of C0 semigroups on Banach spaces to operator-norm approximation of analytic semigroups with error estimate. As application we obtain a criterion for the operator-norm convergence of the Trotter product formula on Banach spaces with error estimate n−1 log n, provided one of the generators has a bounded H∞ functional calculus. For both results, we present versions for approximation in operator-ideal-norms such as the trace norm or the Hilbert-Schmidt norm. Finally, we give some remarks on the operator-norm convergence of the Trotter product formula for semigroups acting on a scale of Lp-spaces. 相似文献
18.
We obtain results on the convergence of Galerkin solutions and continuous dependence on data for the spectrally-hyperviscous Navier-Stokes equations. Let uN denote the Galerkin approximates to the solution u, and let wN=u−uN. Then our main result uses the decomposition wN=PnwN+QnwN where (for fixed n) Pn is the projection onto the first n eigenspaces of A=−Δ and Qn=I−Pn. For assumptions on n that compare well with those in related previous results, the convergence of ‖QnwN(t)Hβ‖ as N→∞ depends linearly on key parameters (and on negative powers of λn), thus reflective of Kolmogorov-theory predictions that in high wavenumber modes viscous (i.e. linear) effects dominate. Meanwhile ‖PnwN(t)Hβ‖ satisfies a more standard exponential estimate, with positive, but fractional, dependence on λn. Modifications of these estimates demonstrate continuous dependence on data. 相似文献
19.
Nenad Mora?a 《Linear algebra and its applications》2008,429(10):2589-2601
In the first part, we obtain two easily calculable lower bounds for ‖A-1‖, where ‖·‖ is an arbitrary matrix norm, in the case when A is an M-matrix, using first row sums and then column sums. Using those results, we obtain the characterization of M-matrices whose inverses are stochastic matrices. With different approach, we give another easily calculable lower bounds for ‖A-1‖∞ and ‖A-1‖1 in the case when A is an M-matrix. In the second part, using the results from the first part, we obtain our main result, an easily calculable upper bound for ‖A-1‖1 in the case when A is an SDD matrix, thus improving the known bound. All mentioned norm bounds can be used for bounding the smallest singular value of a matrix. 相似文献
20.
The Cheeger problem for a bounded domain Ω⊂RN, N>1 consists in minimizing the quotients |∂E|/|E| among all smooth subdomains E⊂Ω and the Cheeger constant h(Ω) is the minimum of these quotients. Let be the p-torsion function, that is, the solution of torsional creep problem −Δp?p=1 in Ω, ?p=0 on ∂Ω, where Δpu:=div(|∇u|p−2∇u) is the p-Laplacian operator, p>1. The paper emphasizes the connection between these problems. We prove that . Moreover, we deduce the relation limp→1+‖?p‖L1(Ω)?CNlimp→1+‖?p‖L∞(Ω) where CN is a constant depending only of N and h(Ω), explicitely given in the paper. An eigenfunction u∈BV(Ω)∩L∞(Ω) of the Dirichlet 1-Laplacian is obtained as the strong L1 limit, as p→1+, of a subsequence of the family {?p/‖?p‖L1(Ω)}p>1. Almost all t-level sets Et of u are Cheeger sets and our estimates of u on the Cheeger set |E0| yield |B1|hN(B1)?|E0|hN(Ω), where B1 is the unit ball in RN. For Ω convex we obtain u=|E0|−1χE0. 相似文献