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101.
Evangelia Samiou 《Geometriae Dedicata》1997,65(2):161-165
A Riemannian manifold M is called 2-flat homogeneous if every geodesic is contained in some 2-flat , and if the group of isometries of M acts transitively on the set of pairs (p, ) with p . By a 2-flat we mean a closed, connected, flat, totally geodesic, 2-dimensional submanifold of M. It is proved in the paper that 2-flat homogeneous spaces are symmetric. 相似文献
102.
In this paper we prove that the moduli spaces MI
2n+1(k) of mathematical instanton bundles on 2n+1
with quantum number k are singular for n 2 and k 3 ,giving a positive answer to a conjecture made by Ancona and Ottaviani in 1993. 相似文献
103.
104.
在α和q满足适当的条件下,当初值属于Fourier-Herz空间?q1-2α(R3)时,我们建立了广义3维不可压旋转Navier-Stokes方程温和解的整体适定性和解析性.作为推论,我们也给出了广义Navier-Stokes方程的相应结论. 相似文献
105.
应用核的分解,讨论了粗糙核奇异积分算子
Tf(x)=p.v.∫R^nΩ(x-y)/|x-y|^nf(y)dy
和BMO(R^n)函数b生成的交换子[b,T]的有界性.证明了当Ω∈L(logL)^2(S^n-1)时,[b,T]是Triebel—Lizorhn空间Fp^α,q(R^n)上的有界算子. 相似文献
106.
B. R. Barmish 《Journal of Optimization Theory and Applications》1978,26(3):379-394
S is taken to be a dynamical system (described by Banach space operators) whose outputy we wish to regulate. The structural complexity ofS (nonlinearities, distributed parameters, etc.) forces us to design a controller forS using an approximate modelM ofS. A convex error bound ? describes the accuracy of the approximation ofS byM. For a prescribed target setY t , we considered the problem of driving the output ofS toY t subject to worst possible error excursions betweenM andS. The notion of areconstructed support function is instrumental to the derivation of the main result, Theorem 6.1, which we can paraphrase as follows. IfM is linear (S need not be), then we can describe a finite-dimensional convex programming Problem (P), whose solution tells us whether or notY t is reachable. Theorem 6.1 is then specialized to differential systems approximated in the norm. The computation of numerical solutions is also discussed. 相似文献
107.
108.
Let T:D⊂X→X be an iteration function in a complete metric space X. In this paper we present some new general complete convergence theorems for the Picard iteration xn+1=Txn with order of convergence at least r≥1. Each of these theorems contains a priori and a posteriori error estimates as well as some other estimates. A central role in the new theory is played by the notions of a function of initial conditions of T and a convergence function of T. We study the convergence of the Picard iteration associated to T with respect to a function of initial conditions E:D→X. The initial conditions in our convergence results utilize only information at the starting point x0. More precisely, the initial conditions are given in the form E(x0)∈J, where J is an interval on R+ containing 0. The new convergence theory is applied to the Newton iteration in Banach spaces. We establish three complete ω-versions of the famous semilocal Newton–Kantorovich theorem as well as a complete version of the famous semilocal α-theorem of Smale for analytic functions. 相似文献
109.
We investigate the parameter dynamics of eigenvalues of Hamiltonians (‘level dynamics’) defined on symmetric spaces relevant to condensed matter and particle physics. In particular we: (1) identify the appropriate reduced manifold on which the motion takes place, (2) identify the correct Poisson structure ensuring the Hamiltonian character of the reduced dynamics, (3) determine the canonical measure on the reduced space, (4) calculate the resulting eigenvalue density. 相似文献
110.
Giovanni Calvaruso Reinier Storm Joeri Van der Veken 《Mathematische Nachrichten》2020,293(9):1707-1729
We classify totally geodesic and parallel hypersurfaces of four-dimensional non-reductive homogeneous pseudo-Riemannian manifolds. 相似文献