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111.
J M Landsberg 《Compositio Mathematica》1999,118(2):189-201
Let XP be a variety (respectively an open subset of an analytic submanifold) and let xX be a point where all integer valued differential invariants are locally constant. We show that if the projective second fundamental form of X at x is isomorphic to the second fundamental form of a point of a Segre P× P, n,m2, a Grassmaniann G(2,n+2), n4, or the Cayley plane OP2, then X is the corresponding homogeneous variety (resp. an open subset of the corresponding homogeneous variety). The case of the Segre P2×P2 had been conjectured by Griffiths and Harris in [GH]. If the projective second fundamental form of X at x is isomorphic to the second fundamental form of a point of a Veronese v2(P) and the Fubini cubic form of X at x is zero, then X=v2 (P) (resp. an open subset of v2(P)). All these results are valid in the real or complex analytic categories and locally in the C category if one assumes the hypotheses hold in a neighborhood of any point x. As a byproduct, we show that the systems of quadrics I2(P P) S2C, I2(P1× P) S2C and I2(S5) S2C16 are stable in the sense that if A S* is an analytic family such that for t0,AA, then A0A. We also make some observations related to the Fulton–:Hansen connectedness theorem. 相似文献
112.
Vladimir V. Kisil 《Acta Appl Math》1999,59(1):79-109
We describe a construction of wavelets (coherent states) in Banach spaces generated by admissible group representations. Our main targets are applications in pure mathematics while connections with quantum mechanics are mentioned. As an example, we consider operator-valued Segal–Bargmann-type spaces and the Weyl functional calculus. 相似文献
113.
A. Y. Lee 《Journal of Optimization Theory and Applications》1988,57(3):519-536
Neighboring extremals of dynamic optimization problems with path equality constraints and with an unknown parameter vector
are considered in this paper. With some simplifications, the problem is reduced to solving a linear, time-varying two-point
boundary-value problem with integral path equality constraints. A modified backward sweep method is used to solve this problem.
Two example problems are solved to illustrate the validity and usefulness of the solution technique.
This research was supported in part by the National Aeronautics and Space Administration under NASA Grant No. NCC-2-106.
The author is indebted to Professor A. E. Bryson, Jr., Department of Aeronautics and Astronautics, Stanford University, for
many stimulating discussions. 相似文献
114.
Iain A. Stewart 《Mathematical Logic Quarterly》1997,43(1):1-21
We investigate the definability in monadic ∑11 and monadic Π11 of the problems REGk, of whether there is a regular subgraph of degree k in some given graph, and XREGk, of whether, for a given rooted graph, there is a regular subgraph of degree k in which the root has degree k, and their restrictions to graphs in which every vertex has degree at most k, namely REGkk and XREGkk, respectively, for k ≥ 2 (all our graphs are undirected). Our motivation partly stems from the fact (which we prove here) that REGkk and XREGkk are logspace equivalent to CONN and REACH, respectively, for k ≥ 3, where CONN is the problem of whether a given graph is connected and REACH is the problem of whether a given graph has a path joining two given vertices. We use monadic first - order reductions, monadic ∑11 games and a recent technique due to Fagin, Stockmeyer and Vardi to almost completely classify whether these problems are definable in monadic ∑11 and monadic Π11, and we compare the definability of these problems (in monadic ∑11 and monadic Π11 with their computational complexity (which varies from solvable using logspace to NP - complete). 相似文献
115.
116.
According to the universal entropy bound, the entropy (and hence information capacity) of a complete weakly self-gravitating
physical system can be bounded exclusively in terms of its circumscribing radius and total gravitating energy. The bound’s
correctness is supported by explicit statistical calculations of entropy, gedanken experiments involving the generalized second
law, and Bousso’s covariant holographic bound. On the other hand, it is not always obvious in a particular example how the
system avoids having too many states for given energy, and hence violating the bound. We analyze in detail several purported
counterexamples of this type, and exhibit in each case the mechanism behind the bound’s efficacy.
In memoriam Asher Peres. 相似文献
117.
T.?HayatEmail author K.?Hutter S.?Nadeem S.?Asghar 《Zeitschrift für Angewandte Mathematik und Physik (ZAMP)》2004,55(4):626-641
The purpose of this work is to investigate the hydromagnetic oscillatory flow of a fluid
bounded by a porous plate, when the entire system rotates about an axis normal to the plate. The
fluid is assumed to be non-Newtonian (second grade), incompressible and electrically conducting.
The magnetic field is applied transversely to the direction of the flow. Such a flow model has
great significance not only of its theoretical interest, but also for applications to geophysics
and engineering. The resulting initial value problem has been solved analytically for steady and
unsteady cases. The analysis of the obtained results showed that the flow field is appreciably
influenced by the material parameter of the second grade fluid, the applied magnetic field, the
imposed frequency, rotation and suction and blowing parameters. It is observed in a second grade
fluid that a steady asymptotic hydromagnetic solution exists for blowing and resonance which is
different from the hydrodynamic situation. 相似文献
118.
A Note on the Oscillation of Second Order Differential Equations 总被引:1,自引:0,他引:1
We give a sufficient condition for the oscillation of linear homogeneous second order differential equation y + p(x)y + q(x)y = 0, where and is positive real number. 相似文献
119.
Evgenia H. Papageorgiou Nikolaos S. Papageorgiou 《Proceedings of the American Mathematical Society》2004,132(2):429-434
In this paper we study a nonlinear periodic problem driven by the ordinary scalar p-Laplacian and with a Carathéodory nonlinearity. We establish the existence of at least two nontrivial solutions. Our approach is variational based on the smooth critical point theory and using the ``Second Deformation Theorem".
120.
G. Criscuolo. 《Mathematics of Computation》2004,73(245):243-250
Recently, Mastroianni and Monegato derived error estimates for a numerical approach to evaluate the integral
where or or and is a smooth function (see G. Mastroianni and G. Monegato, Error estimates in the numerical evaluation of some BEM singular integrals, Math. Comp. 70 2001, 251-267). The error bounds for the quadrature rule approximating the inner integral given in Theorems 3, 4 of that paper are not correct according to the proof. However, following a different approach, we are able to improve the pointwise error estimates given in that paper.
where or or and is a smooth function (see G. Mastroianni and G. Monegato, Error estimates in the numerical evaluation of some BEM singular integrals, Math. Comp. 70 2001, 251-267). The error bounds for the quadrature rule approximating the inner integral given in Theorems 3, 4 of that paper are not correct according to the proof. However, following a different approach, we are able to improve the pointwise error estimates given in that paper.