共查询到10条相似文献,搜索用时 46 毫秒
1.
在Orlicz—Sobolev空间中利用临界点理论考虑了非齐次拟线性椭圆方程{-div((︱▽u︱)▽u)=μ︱u︱q-2u+λ︱u︱p-2u在Ω中,u=0在Ω上无穷多解的存在性,其中Ω是R~N中边界光滑的有界区域,μ,λ∈R是两个参数. 相似文献
2.
设C 是加法范畴, 态射φ,η: X→ X 是C上的态射. 若φ,η 具有Drazin逆且φη =0, 则φ+η 也具有Drazin逆. 若φ具有Drazin逆φD 且1X+φDη 可逆, 作者讨论f =φ+η 的Drazin逆( 群逆)并且给出 f D(f #}=(1X+φDη)-1φD的充分必要条件. 最后, 把Huylebrouck的结果从群逆推广到了Drazin逆. 相似文献
3.
该文首先研究具有脉冲的线性Dirichlet边值问题
$\left\{
\begin{array}{ll}
x'(t)+a(t)x(t)=0, t\neq \tau_{k}, \ \Delta x(\tau_{k})=c_{k}x(\tau_{k}),\ \Delta x'(\tau_{k})=d_{k}x(\tau_{k}), \ x(0)=x(T)=0,
\end{array}
\right. (k=1,2\cdots,m)
$
给出该Dirichlet边值问题仅有零解的两个充分条件, 其中$a:[0,T]\rightarrow R$, $c_{k}, d_{k}, k=1,2,$ $\cdots,m$是常数, 该文首先研究具有脉冲的线性Dirichlet边值问题
$$\left\{
\begin{array}{ll}
x'(t)+a(t)x(t)=0, t\neq \tau_{k}, \ \Delta x(\tau_{k})=c_{k}x(\tau_{k}),\ \Delta x'(\tau_{k})=d_{k}x(\tau_{k}), \ x(0)=x(T)=0,
\end{array}
\right. (k=1,2\cdots,m)
$$
给出该Dirichlet边值问题仅有零解的两个充分条件, 其中$a:[0,T]\rightarrow R$, $c_{k}, d_{k}, k=1,2,$ $\cdots,m$是常数, $0<\tau_{1}<\tau_{2}\cdots<\tau_{m}<T$为脉冲时刻. 其次利用上面的线性边值问题仅有零解这个性质和Leray-Schauder度理论, 研究具有脉冲的非线性Dirichlet边值问题
$$\left\{
\begin{array}{ll}
x'(t)+f(t,x(t))=0, t\neq \tau_{k}, \ \Delta x(\tau_{k})=I_{k}(x(\tau_{k})), \ \Delta x'(\tau_{k})=M_{k}(x(\tau_{k})), \ x(0)=x(T)=0
\end{array}
\right. (k=1,2\cdots,m)
$$ 解的存在性和唯一性, 其中 $f\in C([0,T]\times
R,R)$, $I_{k},M_{k}\in C(R, R),k=1,2,\cdots,m$.
该文主要定理的一个推论将经典的Lyaponov不等式比较完美地推广到脉冲系统. 相似文献
4.
设P 是一个概率测度,ψ是一个复值可积函数,dμ =ψdP是一个复值测度. 在权函数ψ∈a1∩b∝+和Banach空间X 具有适当的凸性和光滑性的条件下, 作者证明了关于复测度μ 的X值拟鞅空间Dα(X) 和pQα(X) 上的原子分解定理. 并且利用复测度拟鞅的原子分解定理, 在0<α≤ 1 的情形, 证明了关于X 值复测度拟鞅的两个重要不等式. 相似文献
5.
Greedily Finding a Dense Subgraph 总被引:3,自引:0,他引:3
Yuichi Asahiro Kazuo Iwama Hisao Tamaki Takeshi Tokuyama 《Journal of Algorithms in Cognition, Informatics and Logic》2000,34(2):203
Given an n-vertex graph with nonnegative edge weights and a positive integer k ≤ n, our goal is to find a k-vertex subgraph with the maximum weight. We study the following greedy algorithm for this problem: repeatedly remove a vertex with the minimum weighted-degree in the currently remaining graph, until exactly k vertices are left. We derive tight bounds on the worst case approximation ratio R of this greedy algorithm: (1/2 + n/2k)2 − O(n − 1/3) ≤ R ≤ (1/2 + n/2k)2 + O(1/n) for k in the range n/3 ≤ k ≤ n and 2(n/k − 1) − O(1/k) ≤ R ≤ 2(n/k − 1) + O(n/k2) for k < n/3. For k = n/2, for example, these bounds are 9/4 ± O(1/n), improving on naive lower and upper bounds of 2 and 4, respectively. The upper bound for general k compares well with currently the best (and much more complicated) approximation algorithm based on semidefinite programming. 相似文献
6.
In this paper, we study the initial-boundary value problem of the porous medium equation u
t
= Δu
m
+ V(x)u
p
in a cone D = (0, ∞) × Ω, where V(x) ~ (1 + |x|)
σ
. Let ω
1 denote the smallest Dirichlet eigenvalue for the Laplace–Beltrami operator on Ω and let l denote the positive root of l
2 + (n − 2)l = ω
1. We prove that if m ≤ p ≤ m + (2 + σ)/(n + l), then the problem has no global nonnegative solutions for any nonnegative u
0 unless u
0 = 0; if p > m + (2 + σ)/n, then the problem has global solutions for some u
0 ≥ 0. 相似文献
7.
Thanh Van Nguyen 《Advances in Applied Clifford Algebras》2011,21(3):591-605
This paper deals with the initial value problem of the type ${\frac{\partial{w}}{\partial{t}}}=L\left(t,x,w,{\frac{\partial{w}}{\partial{x_i}}}\right)\quad\quad\quad\quad\quad\quad\quad\quad\quad\quad\quad(1)$ $w(0,x)=\varphi(x)\quad\quad\quad\quad\quad\quad\quad\quad\quad\quad\quad\quad\quad\quad\quad(2)$ where t is the time, L is a linear first order operator (matrix-type) in Quaternionic Analysis and ${\varphi}This paper deals with the initial value problem of the type
\frac?w?t=L(t,x,w,\frac?w?xi) (1){\frac{\partial{w}}{\partial{t}}}=L\left(t,x,w,{\frac{\partial{w}}{\partial{x_i}}}\right)\quad\quad\quad\quad\quad\quad\quad\quad\quad\quad\quad(1) 相似文献
8.
d 《European Journal of Combinatorics》2002,23(8):1079
Assume that d ≥ 4. Then there exists a d -dimensional dual hyperoval in PG(d + n, 2) for d + 1 ≤ n ≤ 3 d − 7. 相似文献
9.
E. J. Cheon 《Designs, Codes and Cryptography》2009,51(1):9-20
In this paper, we determine the smallest lengths of linear codes with some minimum distances. We construct a [g
q
(k, d) + 1, k, d]
q
code for sq
k-1 − sq
k-2 − q
s
− q
2 + 1 ≤ d ≤ sq
k-1 − sq
k-2 − q
s
with 3 ≤ s ≤ k − 2 and q ≥ s + 1. Then we get n
q
(k, d) = g
q
(k, d) + 1 for (k − 2)q
k-1 − (k − 1)q
k-2 − q
2 + 1 ≤ d ≤ (k − 2)q
k-1 − (k − 1)q
k-2, k ≥ 6, q ≥ 2k − 3; and sq
k-1 − sq
k-2 − q
s
− q + 1 ≤ d ≤ sq
k-1 − sq
k-2 − q
s
, s ≥ 2, k ≥ 2s + 1 and q ≥ 2s − 1.
This work was partially supported by the Com2MaC-SRC/ERC program of MOST/KOSEF (grant # R11-1999-054) and was partially supported by the Korea Research Foundation Grant funded by the Korean Government(MOEHRD)(KRF-2005-214-C00175). 相似文献
10.
该文运用锥上的不动点定理研究非线性二阶常微分方程无穷多点边值问题
u'+a (t ) f (u)=0, t∈(0, 1),
u(0)=0, u(1)=∑∞i =1α i u ( ξ i )
正解的存在性. 其中ξ i∈ (0,1),α i∈ [0,∞), 且满足∑∞i=1αiξ i <1.α∈C([0,1], [0,)),f∈C ([0,∞), [0,∞)). 相似文献
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