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1.
We prove global Lipschitz regularity for solutionsu : Ω → ℝ
N
of some relaxed variational problems in classes of functions with prescribed Dirichlet boundary data. The variational integrals
under consideration are of the form ∫Ω
W(▽
u
)dx withW of quadratic growth. 相似文献
2.
Guido Cortesani 《Annali dell'Universita di Ferrara》1997,43(1):27-49
Let Ω be an open and bounded subset ofR
n
with locally Lipschitz boundary. We prove that the functionsv∈SBV(Ω,R
m
) whose jump setS
vis essentially closed and polyhedral and which are of classW
k, ∞ (S
v,R
m) for every integerk are strongly dense inGSBV
p(Ω,R
m
), in the sense that every functionu inGSBV
p(Ω,R
m
) is approximated inL
p(Ω,R
m
) by a sequence of functions {v
k{j∈N with the described regularity such that the approximate gradients ∇v
jconverge inL
p(Ω,R
nm
) to the approximate gradient ∇u and the (n−1)-dimensional measure of the jump setsS
v
j converges to the (n−1)-dimensional measure ofS
u. The structure ofS
v can be further improved in casep≤2.
Sunto Sia Ω un aperto limitato diR n con frontiera localmente Lipschitziana. In questo lavoro si dimostra che le funzioniv∈SBV(Ω,R m ) con insieme di saltoS v essenzialmente chiuso e poliedrale che sono di classeW k, ∞ (S v,R m ) per ogni interok sono fortemente dense inGSBV p(Ω,R m ), nel senso che ogni funzioneu∈GSBV p(Ω,R m ) è approssimata inL p(Ω,R m ) da una successione di funzioni {v j}j∈N con la regolaritá descritta tali che i gradienti approssimati ∇v jconvergono inL p(Ω,R nm ) al gradiente approssimato ∇u e la misura (n−1)-dimensionale degli insiemi di saltoS v jconverge alla misura (n−1)-dimensionale diS u. La struttura diS vpuó essere migliorata nel caso in cuip≤2.相似文献
3.
Area,coarea, and approximation in <Emphasis Type="Italic">W</Emphasis><Superscript>1,1</Superscript>
David Swanson 《Arkiv f?r Matematik》2007,45(2):381-399
Let Ω⊂ℝ
n
be an arbitrary open set. We characterize the space W
1,1
loc(Ω) using variants of the classical area and coarea formulas. We use these characterizations to obtain a norm approximation
and trace theorems for functions in the space W
1,1(ℝ
n
). 相似文献
4.
Zeng Jian LOU Shou Zhi YANG Dao Jin SONG 《数学学报(英文版)》2005,21(4):949-954
We give a decomposition of the Hardy space Hz^1(Ω) into "div-curl" quantities for Lipschitz domains in R^n. We also prove a decomposition of Hz^1(Ω) into Jacobians det Du, u ∈ W0^1,2 (Ω,R^2) for Ω in R^2. This partially answers a well-known open problem. 相似文献
5.
Andreas Fr?hlich 《Annali dell'Universita di Ferrara》2000,46(1):11-19
We consider weights of Muckenhoupt classA
q, 1<q<∞. For a bounded Lipschitz domain Ω⊂ℝn we prove a compact embedding and a Poincaré inequality in weighted Sobolev spaces. These technical tools allow us to solve
the weak Neumann problem for the Laplace equation in weighted spaces on ℝn, ℝn
+, on bounded and on exterior domains Ω with boundary of classC
1, which will yield the Helmholtz decomposition ofL
ω
q(Ω)n for general ω∈A
q. This is done by transferring the method of Simader and Sohr [4] to the weighted case. Our result generalizes a result of
Farwig and Sohr [2] where the Helmholtz decomposition ofL
ω
p(Ω)n is proved for an exterior domain and weights of Muckenhoupt class without singularities or degeneracies in a neighbourhood
of ϖΩ.
Sunto In questo lavoro consideriamo dei pesi della classe di MuckenhouptA q, 1<q<∞. Per un dominio limitato lipschitziano Ω⊂ℝn, dimostriamo una immersione compatta ed una disuguaglianza di Poincaré in spazi di Sobolev con peso. Questa tecnica ci consente di risolvere il problema debole di Neumann per l’equazione di Laplace in spazi pesati in ℝn, ℝn + in domini limitati ed in domini esterni con frontiera di classeC 1, che conduce alla decomposizione di Helmholtz diL ω q(Ω)n per un qualsiasi ω∈A q. Il risultato è ottenuto trasferendo il metodo di Simader e Sohr [4] al caso pesato. Quello qui presente estende un risultato di Farwig e Sohr [2] dove la decomposizione di Helmholtz diL ω q(Ω)n è dimostrata per domini esterni e pesi della classe di Muckenhoupt privi di singolarità in un intorno di ϖΩ.相似文献
6.
Stephen J. Gardiner 《Journal d'Analyse Mathématique》1996,68(1):95-106
Let Ω be an open set in ℝ
n
andE be a relatively closed subset of Ω. Further, letC
e(E) be the collection of real-valued continuous functions onE which extend continuously to the closure ofE in ℝ
n
. We characterize those pairs (Ω,E) which have the following property: every function inC
e(E) which is harmonic onE
0 can be uniformly approximated onE by functions which are harmonic on Ω and whose restrictions toE belong toC
e(E). 相似文献
7.
Robert Černý 《Central European Journal of Mathematics》2012,10(2):590-602
Let Ω ⊂ ℝ
n
, n ≥ 2, be a bounded domain and let α < n − 1. Motivated by Theorem I.6 and Remark I.18 of [Lions P.-L., The concentration-compactness principle in the calculus of
variations. The limit case. I, Rev. Mat. Iberoamericana, 1985, 1(1), 145–201] and by the results of [Černy R., Cianchi A.,
Hencl S., Concentration-Compactness Principle for Moser-Trudinger inequalities: new results and proofs, Ann. Mat. Pura Appl.
(in press), DOI: 10.1007/s10231-011-0220-3], we give a sharp estimate of the exponent concerning the Concentration-Compactness
Principle for the embedding of the Orlicz-Sobolev space W
01
L
n
log
α
L(Ω) into the Orlicz space corresponding to a Young function that behaves like exp t
n/(n−1−α) for large t. We also give the result for the case of the embedding into double and other multiple exponential spaces. 相似文献
8.
A. P. Oskolkov 《Journal of Mathematical Sciences》1997,83(2):320-326
In this paper, we study some nonlocal problems for the Kelvin-Voight equations (1) and the penalized Kelvin-Voight equations
(2): the first and second initial boundary-value problems and the first and second time periodic boundary problems. We prove
that these problems have global smooth solutions of the classW
∞
1
(ℝ+;W
2
2+k
(Ω)),k=1,2,...;Ω⊂ℝ3. Bibliography: 25 titles.
Dedicated to N. N. Uraltseva on her jubilee
Translated fromZapiski Nauchnykh Seminarov POMI, Vol. 221, 1995, pp. 185–207.
Translated by N. A. Karazeeva. 相似文献
9.
Aissa Guesmia 《Israel Journal of Mathematics》2001,125(1):83-92
We consider in this paper the evolution systemy″−Ay=0, whereA =∂
i(aij∂j) anda
ij ∈C
1 (ℝ+;W
1,∞ (Ω)) ∩W
1,∞ (Ω × ℝ+), with initial data given by (y
0,y
1) ∈L
2(Ω) ×H
−1 (Ω) and the nonhomogeneous conditiony=v on Γ ×]0,T[. Exact controllability means that there exist a timeT>0 and a controlv such thaty(T, v)=y′(T, v)=0. The main result of this paper is to prove that the above system is exactly controllable whenT is “sufficiently large”. Moreover, we obtain sharper estimates onT. 相似文献
10.
Let Ω be a bounded Lipschitz domain. Define B
0,1
1,
r
(Ω) = {f∈L
1 (Ω): there is an F∈B
0,1
1 (ℝ
n
) such that F|Ω = f} and B
0,1
1
z
(Ω) = {f∈B
0,1
1 (ℝ
n
) : f = 0 on ℝ
n
\}. In this paper, the authors establish the atomic decompositions of these spaces. As by-products, the authors obtained the
regularity on these spaces of the solutions to the Dirichlet problem and the Neumann problem of the Laplace equation of ℝ
n
+.
Received June 8, 2000, Accepted October 24, 2000 相似文献
11.
We consider finite element methods applied to a class of Sobolev equations inR d(d ≥ 1). Global strong superconvergence, which only requires that partitions are quais-uniform, is investigated for the error between the approximate solution and the Ritz-Sobolev projection of the exact solution. Two order superconvergence results are demonstrated inW 1,p (Ω) andL p(Ω) for 2 ≤p < ∞. 相似文献
12.
Jack D. Koronel 《Israel Journal of Mathematics》1976,24(2):119-138
The paper gives a necessary and sufficient condition for the embedding of the Orlicz-Sobolev spaceW
kLA (Ω) inC(Ω). The same condition is also found to be necessary and sufficient so that a continuous function inW
kLA (Ω) be differentiable of orderk almost everywhere in Ω. 相似文献
13.
Flavia Giannetti Tadeusz Iwaniec Jani Onninen Anna Verde 《Journal of Geometric Analysis》2002,12(2):223-254
Let ƒ: Ω → ℝn be a mapping in the Sobolev space W1,n−1(Ω,ℝn), n ≥ 2. We assume that the determinant of the differential matrix Dƒ (x) is nonnegative, while the cofactor matrix D#ƒ satisfies
, where Lp(Ω) is an Orlicz space. We show that, under the natural Divergence Condition on P, see (1.10), the Jacobian lies in L
loc
1
(Ω). Estimates above and below L
loc
1
(Ω) are also studied. These results are stronger than the previously known estimates, having assumed integrability conditions
on the differential matrix. 相似文献
14.
Morten Nielsen 《Journal of Geometric Analysis》2012,22(1):12-22
We consider a periodic matrix weight W defined on ℝ
d
and taking values in the N×N positive-definite matrices. For such weights, we prove transference results between multiplier operators on L
p
(ℝ
d
;W) and
Lp(\mathbb Td;W)L_{p}(\mathbb {T}^{d};W), 1<p<∞, respectively. As a specific application, we study transference results for homogeneous multipliers of degree zero. 相似文献
15.
A. P. Oskolkov 《Journal of Mathematical Sciences》1998,91(2):2840-2859
Existence theorems are proved for the solutions of the first and second initial boundary-value problems for the equations
of Kelvin-Voight fluids and for the penalized equations of Kelvin-Voight fluids in the smoothness classes W
∞
r
(ℝ+;W
2
2+k
(Ω)), W
2
r
(ℝ+;W
2
2+k
(Ω)) and S
2
r
(ℝ+;W
2
2+k
(Ω)) (r=1,2; k=0,1,2, …) under the condition that the right-hand sides f(x,t) belong to the classes W
∞
r-1
(ℝ+;W
2
k
(Ω)), W
2
r-1
(ℝ+;W
2
k
(Ω)) and S
2
r-1
(ℝ+;W
2
k
(Ω)), respectively, and for the solutions of the first and second T-periodic boundary-value problems for the same equations
in the smoothness classes W
∞
r−1
(ℝ; W
2
2+k
(Ω)) and W
2
r−1
(0, T; W
2
2+k
(Ω)) (r=1,2, k=0,1,2…) under the condition that f(x,t) are T-periodic and belong to the spaces W
∞
r−1
(ℝ+; W
2
k
(Ω)) and W
2
r−1
(0,T; W
2
k
(Ω)), respectively. It is shown that as ɛ→0, the smooth solutions {vɛ} of the perturbed initial boundary-value and T-periodic boundary-value problems for the penalized equations of Kelvin-Voight
fluids converge to the corresponding smooth solutions (v,p) of the initial boundary-value and T-periodic boundary-value problems
for the equations of Kelvin-Voight fluids. Bibliography: 27 titles.
Translated fromZapiski Nauchnykh Seminarov POMI, Vol. 230, 1995, pp. 214–242.
Translated by T. N. Surkova. 相似文献
16.
Soulaymane Korry 《Israel Journal of Mathematics》2003,133(1):357-367
Letp∈(1, +∞) ands ∈ (0, +∞) be two real numbers, and letH
p
s
(ℝ
n
) denote the Sobolev space defined with Bessel potentials. We give a classA of operators, such thatB
s,p
-almost all points ℝ
n
are Lebesgue points ofT(f), for allf ∈H
p
s
(ℝ
n
) and allT ∈A (B
s,p
denotes the Bessel capacity); this extends the result of Bagby and Ziemer (cf. [2], [15]) and Bojarski-Hajlasz [4], valid
wheneverT is the identity operator. Furthermore, we describe an interesting special subclassC ofA (C contains the Hardy-Littlewood maximal operator, Littlewood-Paley square functions and the absolute value operatorT: f→|f|) such that, for everyf ∈H
p
s
(ℝ
n
) and everyT ∈C, T(f) is quasiuniformly continuous in ℝ
n
; this yields an improvement of the Meyers result [10] which asserts that everyf ∈H
p
s
(ℝ
n
) is quasicontinuous. However,T (f) does not belong, in general, toH
p
s
(ℝ
n
) wheneverT ∈C ands≥1+1/p (cf. Bourdaud-Kateb [5] or Korry [7]). 相似文献
17.
Roger D. Nussbaum 《Israel Journal of Mathematics》1991,76(3):345-380
Suppose thatE is a finite-dimensional Banach space with a polyhedral norm ‖·‖, i.e., a norm such that the unit ball inE is a polyhedron. ℝ
n
with the sup norm or ℝ
n
with thel
1-norm are important examples. IfD is a bounded set inE andT:D→D is a map such that ‖T(y)−T(z)‖≤ ‖y−z‖ for ally andz inE, thenT is called nonexpansive with respect to ‖·‖, and it is known that for eachx ∈D there is an integerp=p(x) such that lim
j→∞
T
jp
(x) exists. Furthermore, there exists an integerN, depending only on the dimension ofE and the polyhedral norm onE, such thatp(x)≤N: see [1,12,18,19] and the references to the literature there. In [15], Scheutzow has raised a question about the optimal
choice ofN whenE=ℝ
n
,D=K
n
, the set of nonnegative vectors in ℝ
n
, and the norm is thel
1-norm. We provide here a reasonably sharp answer to Scheutzow’s question, and in fact we provide a systematic way to generate
examples and use this approach to prove that our estimates are optimal forn≤24. See Theorem 2.1, Table 2.1 and the examples in Section 3. As we show in Corollary 2.3, these results also provide information
about the caseD=ℝ
n
, i.e.,T:ℝ
n
→ℝ
n
isl
1-nonexpansive. In addition, it is conjectured in [12] thatN=2
n
whenE=ℝ
n
and the norm is the sup norm, and such a result is optimal, if true. Our theorems here show that a sharper result is true
for an important subclass of nonexpansive mapsT:(ℝ
n
,‖ · ‖∞)→(ℝ
n
,‖ · ‖∞).
Partially supported by NSF DMS89-03018. 相似文献
18.
SAUGATA BANDYOPADHYAY 《Proceedings Mathematical Sciences》2011,121(3):339-348
Let Ω ⊂ ℝ
n
be a smooth, bounded domain. We study the existence and regularity of diffeomorphisms of Ω satisfying the volume form equation
f*(g)=f, \textin W, \phi^\ast(g)=f, \quad \text{in }\Omega, 相似文献
19.
O. V. Matveev 《Mathematical Notes》1997,62(3):339-349
Supposem, n ∈ℕ,m≡n (mod 2),K(x)=|x|
m
form odd,K(x)=|x|
m
In |x| form even (x∈ℝ
n
),P is the set of real polynomials inn variables of total degree ≤m/2, andx
1,...,x
N
∈ℝ
n
. We construct a function of the form
20.
We show that in the worst case, Ω(n
d
) sidedness queries are required to determine whether a set ofn points in ℝ
d
is affinely degenerate, i.e., whether it containsd+1 points on a common hyperplane. This matches known upper bounds. We give a straightforward adversary argument, based on
the explicit construction of a point set containing Ω(n
d
) “collapsible” simplices, any one of which can be made degenerate without changing the orientation of any other simplex.
As an immediate corollary, we have an Ω(n
d
) lower bound on the number of sidedness queries required to determine the order type of a set ofn points in ℝ
d
. Using similar techniques, we also show that Ω(n
d+1) in-sphere queries are required to decide the existence of spherical degeneracies in a set ofn points in ℝ
d
.
An earlier version of this paper was presented at the 34th Annual IEEE Symposium on Foundations of Computer Science [8]. This
research has been supported by NSF Presidential Young Investigator Grant CCR-9058440. 相似文献
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