降维梯度法

§1.引言 本文研究降维梯度法,它具有共轭梯度法的一切性质.对于正定二次函数,用不着精确的一维搜索,只要在每步加入两个校正项,即可将高阶问题转化为低阶问题,保证了二     

具间断系数拟线性退化椭圆方程在可控增长下的正则性

对于具有VMO间断系数的散度型拟线性退化椭圆型方程,考虑了低阶项微分项在可控制增长条件下的弱解梯度的Morrey空间L^p,λ局部正则性,从而在已知数据正则性提高的条件下得到弱解具有优化Hlder指数的Hlder连续性结果。     

约束矩阵方程的Hermitian解的共轭梯度迭代算法

本文讨论矩阵方程在子矩阵约束下的Hermitian解的共轭梯度迭代算法,先转化成两个低阶方程,然后利用共轭梯度思想分别构造出低阶方程的共轭梯度迭代算法,运用算法求出矩阵方程的Hermitian解及最佳逼近,最后给出了数值实例来验证算法的有效性.     

带有L~1资料的某类抛物问题熵解的存在性

本文证明了带有L1资料和对以散度形式的低阶项没作任何增长假设的某类 抛物问题熵解的存在性.     

带有L1资料的某类抛物问题熵解的存在性

本文证明了带有L1资料和对以散度形式的低阶项没作任何增长假设的某类抛物问题熵解的存在性.     

由具奇异系数的强椭圆微分算子生成的解析半群

本文提出了低阶项系数具一定奇异性的高阶强椭圆微分算子生成解析半群的条 件,其包含了低阶项系数属于Schecter位势类的情形.特别地,低阶项系数属于LP(Rn) 的情形也在其中.作为应用,得到低阶项系数属于LP(Rn)的强椭圆算子的相应半群生 成,且p还可取到一些临界值.     

自然增长的半线性次椭圆方程内部H?lder估计

对于低阶项满足自然增长条件的半线性次椭圆方程有界弱解,通过Moser-Nash迭代和弱Harnack不等式,得到弱解的内部H?lder连续性估计.     

实子矩阵约束下矩阵方程AX=B的共轭梯度迭代解法

本文研究了实子矩阵约束下矩阵方程AX=B及其最佳逼近的共轭梯度迭代解法.首先运用矩阵分块将原方程AX=B转换为2个低阶方程,利用共轭梯度的思想构造迭代算法;然后证明了算法的有限步终止性;最后给出数值实例验证算法的有效性.     

自然增长下的具VMO系数拟线性椭圆组的部分正则性

设散度型拟线性系数算子关于自变量x一致满足VMO的结构条件,对于低阶项满足自然增长条件的拟线性椭圆方程组,建立了其弱解具有确切Holder指数的部分正则性.     

r阶差等比数列的通项与前n项的和

本文将低阶差等比数列的通项及前n项和的计算公式推广到高阶.     

非线性发展方程的H(o)lder连续惯性流形

引入非线性发展方程的H\"older连续惯性流形的概念,为原来惯性流形概念的推广和修正.惯性流形是有限维不变的Lipschiz流形,是研究发展方程解的长时间性态的合适工具,其缺点是需要谱间隙条件.提出H\"older连续惯性流形也是有限维不变的,但光滑性减弱为H\"older连续,不需要谱间隙条件.该流形与指数吸引子交集具有指数吸引性,无穷维动力系统可在H\"older连续惯性流形上约化为有限维常微分方程组.     

Brown运动增量在H(o)lder范数下关于(r,p)-容度的泛函极限定理

利用Brown运动在H\"older 范数下关于$(r,p)$-容度的大偏差,证明了Brown运动增量在H\"older范数下关于$(r,p)$-容度的泛函极限定理.     

散度型椭圆方程Holder连续性的Green函数法

文中利用散度型非线椭圆性算子的Green函数与Laplacian算子的比较性质, 建立了具有自然增长条件下的散度型非线性椭圆方程弱解的内部H\"older连续性.     

薛定谔型椭圆方程的Morrey估计

利用与分数次积分相关的Olsen型不等式,我们得到了薛定谔型椭圆方程的内部Morrey估计, 其中位势函数满足反H\"older条件.     

A mollification method for ill-posed problems

Summary. A mollification method for a class of ill-posed problems is suggested. The idea of the method is very simple and natural: if the data are given inexactly then we try to find a sequence of ``mollification operators" which map the improper data into well-posedness classes of the problem (mollify the improper data). Within these mollified data our problem becomes well-posed. And when these facts are in hand we try to obtain error estimates and optimal or ``quasi-optimal" mollification parameters. The method is working not only for problems in Hilbert spaces, but also for problems in Banach spaces. Applications of the method to concrete problems, like numerical differentiation, parabolic equations backwards in time, the Cauchy problem for the Laplace equation, one- and multidimensional non-characteristic Cauchy problems for parabolic equations (in infinite or finite domains),... give us very sharp stability estimates of H\"older continuous type. In these cases the method is optimal in the sense that it gives the same order of H\"older continuous dependence on the data as for the regularized problems. Furthermore, the method may be implemented numerically using fast Fourier transforms. For the first time a uniform stability estimate of H\"older continuous type of the solution of the heat equation backwards in time in the space for all could be established by our mollification method. A new simple sharp pointwise estimate of H\"older type for the weak solution of a non-characteristic Cauchy problem for parabolic equations in a finite domain is established. Received June 25, 1993 / Revised version received February 18, 1994     

低于临界增长 p -调和型方程组的完全正则性

当p≥ 2时,得到一类低于临界增长的退化椭圆型方程组弱解微商属于局部Morrey-Campanauo空间$L^{ p,\lambda}$和${\cal L}^{p, \gamma}$;在附加条件下,进一步建立其弱解微商的局部H\"older连续性.     

二参数L{\'e}vy区域在Holder 范数下的局部Strassen重对数律

利用大偏差,得到了二参数L\'evy区域在H\"older 范数下的局部Strassen重对数律.     

Asymptotics of a Solution to the Quasiliniear Neumann Problem in a Neighborhood of a Conical Point

The existence of a small solution to the quasilinear Neumann problem is established in a H\"older class with separated asymptotics. The lower-order asymptotic terms are constructed. The homogeneity exponents of these terms turn out to be dependent on the value of the solution at a conical point. Bibliography: 33 titles.     

{Well-posedness of degenerate differential equations with infinite delay in Holder continuous function spaces

Using operator-valued $\dot{C}^\alpha$-Fourier multiplier results on vector- valued H\"older continuous function spaces, we give a characterization for the $C^\alpha$-well-posedness of the first order degenerate differential equations with infinite delay $(Mu)"(t) = Au(t) + \int_{-\infty}^t a(t-s)Au(s)ds + f(t)$ ($t\in\R$), where $A, M$ are closed operators on a Banach space $X$ such that $D(A)\cap D(M)\neq \{0\}$, $a\in L^1_{\rm{loc}}(\R_+)\cap L^1(\mathbb{R}_+; t^\alpha dt)$.     

一类紧致K¨ahler流形上的Harnack估计

给出了一些紧致~K\"{a}hler~流形上具有和时间相关的位势热方程的正解的Hanack估计.作为应用, 得到了两个~K\"{a}hler-Ricci~流下具有非负双截面曲率的单调熵.