共查询到20条相似文献,搜索用时 46 毫秒
1.
S.-M. Jung 《Acta Mathematica Hungarica》2006,110(3):261-266
Summary We introduce a new characterization of linear isometries. More precisely, we prove that if a one-to-one mapping f:<span style='font-size:10.0pt;font-family:"Lucida Sans Unicode"'>ℝn→ℝn(2<span style='font-size:10.0pt;font-family:"Lucida Sans Unicode"'>≦n<<span style='font-size:10.0pt;font-family:"Lucida Sans Unicode"'>∞) maps every regular pentagon of side length a> 0 onto a pentagon with side length b> 0, then there exists a linear isometry I :<span style='font-size:10.0pt;font-family:"Lucida Sans Unicode"'>ℝn→ℝnup to translation such that f(x) = (b/a) I(x). 相似文献
2.
We derive conditions on the function c : Rn → R which guarantee that the PDE with p-Laplacian div (❘∇ u❘p-2∇ u ) + c(x)❘u❘p-2u =0, p >1, has no positive solution either in Rn or in the domain Omega_r :={x ∈ Rn : ❘x❘ ≧r} with r arbitrarily large.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
3.
Jussi Väisälä 《Israel Journal of Mathematics》2002,128(1):1-27
We give a necessary and sufficient quantitative geometric condition for a compact setA⊂R
n
to have the following property with a givenc≥1: For everyɛ>0 and for every mapf: A→R
n
such that
there is an isometryS: A→R
n
such that |Sx−fx|≤cɛ for allx∈A. 相似文献
4.
Thierry De Pauw 《Journal of Geometric Analysis》2002,12(1):29-61
A concentrated (ξ, m) almost monotone measure inR
n
is a Radon measure Φ satisfying the two following conditions: (1) Θ
m
(Φ,x)≥1 for every x ∈spt (Φ) and (2) for everyx ∈R
n
the ratioexp [ξ(r)]r−mΦ(B(x,r)) is increasing as a function of r>0. Here ξ is an increasing function such thatlim
r→0-ξ(r)=0. We prove that there is a relatively open dense setReg (Φ) ∋spt (Φ) such that at each x∈Reg(Φ) the support of Φ has the following regularity property: given ε>0 and λ>0 there is an m dimensional spaceW ⊂R
n
and a λ-Lipschitz function f from x+W into x+W‖ so that (100-ε)% ofspt(Φ) ∩B (x, r) coincides with the graph of f, at some scale r>0 depending on x, ε, and λ. 相似文献
5.
Walter Senn 《manuscripta mathematica》1991,71(1):45-65
We consider a variational problem with an integrandF:R
n
×R×R
n
→R that isZ-periodic in the firstn+1 variables and satisfies certain growth-conditions. By a recent result of Moser, there exist for every α∈R
n
minimal solutionsu:R
n
→R minimising ƒF(x, u(x), u
x
(x)) dx with respect to compactly supported variations ofu and such that sup |u(x)-αx|<∞. Given such a minimal solutionu we define the average action
(whereB
r
is ther-ball around 0∈R
n
) and show thatM(α) is indeed independent of the minimal solutionu satisfying sup |u(x)-αx|<∞. We prove that this average actionM(α) is strictly convex in α.
相似文献
6.
Soon-Mo Jung Byungbae Kim 《Abhandlungen aus dem Mathematischen Seminar der Universit?t Hamburg》1999,69(1):293-308
A result of Skof and Terracini will be generalized; More precisely, we will prove that if a functionf : [-t, t]n →E satisfies the inequality (1) for some δ > 0 and for allx, y ∈ [-t, t]n withx + y, x - y ∈ [-t, t]n, then there exists a quadratic functionq: ℝn →E such that ∥f(x) -q(x)∥ < (2912n2 + 1872n + 334)δ for anyx ∈ [-t, t]
n
. 相似文献
7.
C. Hamburger 《Applied Mathematics and Optimization》1999,40(2):183-190
Finsler's theorem asserts the equivalence of (i) and (ii) for pairs of real quadratic forms f and g on R
n
: (i) f( ξ ) >0 for all ξ≠ 0 with g( ξ ) =0; (ii) f-λ g>0 for some λ∈
R. We prove two extensions: 1. We admit a vector-valued quadratic form g:
R
n
→
R
k
, for which we show that (i) implies that f-λ . . . g>0 on an ( n-k+1 ) -dimensional subspace Y
R
n
for some λ∈
R
k
. 2. In the nonstrict version of Finsler's theorem for indefinite g we replace R
n
by a real
vector
space
X .
Accepted 22 February 1998 相似文献
8.
YANGZUODONG 《高校应用数学学报(英文版)》1997,12(4):399-410
In this paper,the nonexistence of positive entire solutions for div(|Du|^1-2Du)≥q(x)f(u),x∈R^N,is establisbed,where p>1,DU=(D,u……dnu),qsR^N→(o,∞)and f2(0,∞)→(o,∞)are continuous functions. 相似文献
9.
Abraham Neyman 《Israel Journal of Mathematics》1984,48(2-3):129-138
For fixed 1≦p<∞ theL
p-semi-norms onR
n
are identified with positive linear functionals on the closed linear subspace ofC(R
n
) spanned by the functions |<ξ, ·>|
p
, ξ∈R
n
. For every positive linear functional σ, on that space, the function Φσ:R
n
→R given by Φσ is anL
p-semi-norm and the mapping σ→Φσ is 1-1 and onto. The closed linear span of |<ξ, ·>|
p
, ξ∈R
n
is the space of all even continuous functions that are homogeneous of degreep, ifp is not an even integer and is the space of all homogeneous polynomials of degreep whenp is an even integer. This representation is used to prove that there is no finite list of norm inequalities that characterizes
linear isometric embeddability, in anyL
p unlessp=2.
Supported by the National Science Foundation MCS-79-06634 at U.C. Berkeley. 相似文献
10.
M.M. Cavalcanti V.N. Domingos Cavalcanti 《NoDEA : Nonlinear Differential Equations and Applications》2000,7(3):285-307
This paper is concerned to the existence, uniqueness and uniform decay for the solutions of the coupled Klein-Gordon-Schr?dinger
damped equations
where ω is a bounded domain of R
n
, n≤ 3, F : R
2→R is a C
1-function; γ, β; θ are constants such that γ, β > 0 and 1 ≤ 2θ≤ 2.
Received January 1999 – Accepted October 1999 相似文献
11.
Riccardo De Arcangelis 《Annali dell'Universita di Ferrara》1989,35(1):135-145
Summary Letf: (x, z)∈R
n×Rn→f(x, z)∈[0, +∞] be measurable inx and convex inz.
It is proved, by an example, that even iff verifies a condition as|z|
p≤f(x, z)≤Λ(a(x)+|z|q) with 1<p<q,a∈L
loc
s
(R
n),s>1, the functional
that isL
1(Ω)-lower semicontinuous onW
1,1(Ω), does not agree onW
1,1(Ω) with its relaxed functional in the topologyL
1(Ω) given by inf
Riassunto Siaf: (x, z)∈R n×Rn→f(x, z)∈[0, +∞] misurabile inx e convessa inz. Si mostra con un esempio che anche sef verifica una condizione del tipo|z| p≤f(x, z)≤Λ(a(x)+|z|q) con 1<p<q,a∈L loc s (R n),s>1, il funzionale , che èL 1(Ω)-semicontinuo inferiormente suW 1,1(Ω), non coincide suW 1,1(Ω) con il suo funzionale rilassato nella topologiaL 1(Ω) definito da inf相似文献
12.
Jouko Tervo 《Israel Journal of Mathematics》1988,63(1):41-66
The paper considers a boundary value problem with the help of the smallest closed extensionL
∼ :H
k →H
k
0×B
h
1×...×B
h
N
of a linear operatorL :C
(0)
∞
(R
+
n
) →L(R
+
n
)×L(R
n−1)×...×L(R
n−1). Here the spacesH
k (the spaces ℬ
h
) are appropriate subspaces ofD′(R
+
n
) (ofD′(R
n−1), resp.),L(R
+
n
) andC
(0)
∞
(R
+
n
)) denotes the linear space of smooth functionsR
n
→C, which are restrictions onR
+
n
of a function from the Schwartz classL (fromC
0
∞
, resp.),L(R
n−1) is the Schwartz class of functionsR
n−1 →C andL is constructed by pseudo-differential operators. Criteria for the closedness of the rangeR(L
∼) and for the uniqueness of solutionsL
∼
U=F are expressed. In addition, ana priori estimate for the corresponding boundary value problem is established. 相似文献
13.
Sufficient conditions are established for the solvability of the boundary value problem
where p : C(I; R
n) × C(I; R
n) L(I; R
n), q : C(I; R
n) L(I; R
n), l : C(I, R
n) × C(I; R
n) R
n, and c
n : C(I, R
n) R
n are continuous operators, and p(x, ) and l(x, ) are linear operators for any fixed
. 相似文献
14.
For 0<p<∞, let Hp(R
n) denote the Lebesgue space for p>1 and the Hardy space for p ≤1. In this paper, the authors study Hp(R
n)×Hq(R
n)→Hr(R
n) mapping properties of bilinear operators given by finite sums of the products of the standard fractional integrals or the
standard fractional integral with the Calderón-Zygmund operator. The authors prove that such mapping properties hold if and
only if these operators satisfy certain cancellation conditions.
Supported by the NNSF and the National Education Comittee of China. 相似文献
15.
Chen Jiecheng Zhu Xiangrong 《高校应用数学学报(英文版)》2005,20(3):316-322
Given a positive Radon measure μ on R^d satisfying the linear growth condition μ(B(x,r))≤C0r^n,x∈R^d,r〉0,(1) where n is a fixed number and O〈n≤d. When d-1〈n,it is proved that if Tt,N1=0,then the corresponding maximal Calderon-Zygmund singular integral is bounded from RBMO to itself only except that it is infinite μ-a. e. on R^d. 相似文献
16.
S. E. Pastukhova 《Journal of Mathematical Sciences》2012,181(5):668-700
We consider the operator exponential e
−tA
, t > 0, where A is a selfadjoint positive definite operator corresponding to the diffusion equation in
\mathbbRn {\mathbb{R}^n} with measurable 1-periodic coefficients, and approximate it in the operator norm
|| · ||L2( \mathbbRn ) ? L2( \mathbbRn ) {\left\| {\; \cdot \;} \right\|_{{{L^2}\left( {{\mathbb{R}^n}} \right) \to {L^2}\left( {{\mathbb{R}^n}} \right)}}} with order
O( t - \fracm2 ) O\left( {{t^{{ - \frac{m}{2}}}}} \right) as t → ∞, where m is an arbitrary natural number. To construct approximations we use the homogenized parabolic equation with constant
coefficients, the order of which depends on m and is greater than 2 if m > 2. We also use a collection of 1-periodic functions N
α
(x),
x ? \mathbbRn x \in {\mathbb{R}^n} , with multi-indices α of length
| a| \leqslant m \left| \alpha \right| \leqslant m , that are solutions to certain elliptic problems on the periodicity cell. These results are used to homogenize the diffusion
equation with ε-periodic coefficients, where ε is a small parameter. In particular, under minimal regularity conditions, we construct approximations of order O(ε
m
) in the L
2-norm as ε → 0. Bibliography: 14 titles. 相似文献
17.
M. Perović 《Commentarii Mathematici Helvetici》1986,61(1):60-66
A homeomorphismf:B
n→B
n of the unit ball inR
n(n≥2) whose coefficient of quasiconformality in the ball of radiusr<1 has asymptotic rate of growthK(r)=sup
|x|≤r
k(x, f)=O(log (1/1−r)) can be continued to a homeomorphism
of the closed ball
. Forn=2 this implies that the Caratheodory theory of prime ends for conformal mappings also holds for the class of homeomorphismsf:B
2→D withK(r)=O(log (1/1−r)).
This work was partially supported by SIZ za nauku SRCG, Titograd. 相似文献
18.
W. M. Ruess 《Semigroup Forum》1995,51(1):335-341
For aC
0-contraction semigroup (S(t))
t≥0 of bounded linear operators on a complex Banach spaceX, J. A. Goldstein and B. Nagy [6] have shown that, givenx∈X, S(t)x=e
iλt
x, t≥0, for some λ∈ℝ, provided lim
t→∞
|<S(t)x,x
*
>|=|<x,x
*
>| for allx
*∈X*. We present (a) an extension to the case of nonlinear nonexpansive mapsS(t), t≥0, and (b) various generalizations in the linear context. 相似文献
19.
Given a semi-convex functionu: ω⊂R
n→R and an integerk≡[0,1,n], we show that the set ∑k defined by
相似文献
20.
Thomas J. Cheatham Edgar E. Enochs Overtoun M. G. Jenda 《Israel Journal of Mathematics》1988,63(2):237-242
In this paper, we prove that the injective cover of theR-moduleE(R/B)/R/B for a prime ideal B ofR is the direct sum of copies ofE(R/B) for prime ideals D ⊃ B, and if B is maximal, the injective cover is a finite sum of copies ofE(R/B). For a finitely generatedR-moduleM withn generators andG an injectiveR-module, we argue that the natural mapG
n →G
n/Hom
R
(M, G) is an injective precover if Ext
R
1
(M, R) = 0, and that the converse holds ifG is an injective cogenerator ofR. Consequently, for a maximal ideal R ofR, depthR
R ≧ 2 if and only if the natural mapE(R/R) →E(R/R)/R/R is an injective cover and depthR
R > 0. 相似文献
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