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931.
932.
CHEN Jin-Bing GENG Xian-Guo 《理论物理通讯》2005,44(3):393-395
This paper deals with the integrability of a finite-dimensional Hamiltonian system linked with the generalized coupled KdV hierarchy. For this purpose the associated Lax representation is presented after an elementary calculation. It is shown that the Lax representation enjoys a dynamical r-matrix formula instead of a classical one in the Poisson bracket on R^2N. Consequently the resulting system is proved to be completely integrable in view of its r-matrix structure. 相似文献
933.
本文证明了具有平行平均曲率向量的子流形的二次表示不可能是零2型的,以及若具有平行平均曲率向量的a-子流形的二次表示是2-型的,则它的数量曲率必为常数. 相似文献
934.
Ling Long 《Journal of Number Theory》2004,109(2):299-318
We develop an algorithm to determine a one-parameter family of elliptic curves associated to a one-parameter family of K3 surfaces with generic Picard number 19 by a Shioda-Inose structure. The family of elliptic curves is determined up to an isomorphism and an isogeny. An application to a generalized congruence number problem is also discussed. 相似文献
935.
William Crawley-Boevey 《Compositio Mathematica》2002,130(2):225-239
We decompose the Marsden–Weinstein reductions for the moment map associated to representations of a quiver. The decomposition involves symmetric products of deformations of Kleinian singularities, as well as other terms. As a corollary we deduce that the Marsden–Weinstein reductions are irreducible varieties. 相似文献
936.
The character of the ground state of the electron crystal—an electron gas with periodic density and/or spin density is investigated.
Calculations for non-magnetic, ferromagnetic and anti-ferromagnetic electron crystals based on the Koster-Kohn variational
principle for direct calculation of Wannier functions are presented. The Wannier function is approximated by a symmetrically
orthonormalized Gaussian. The orbital exponent of the Gaussian is used as a variational parameter. The effect of the positive
background is suitably taken into account. The results of our calculation support Wigner’s prediction of electron crystallization. 相似文献
937.
Craig Huneke Graham J. Leuschke 《Proceedings of the American Mathematical Society》2003,131(10):3003-3007
We prove (the excellent case of) Schreyer's conjecture that a local ring with countable CM type has at most a one-dimensional singular locus. Furthermore, we prove that the localization of a Cohen-Macaulay local ring of countable CM type is again of countable CM type.
938.
John S Berry 《The Journal of Mathematical Behavior》2003,22(4):479-495
Our purpose in this paper is to report on an observational study to show how students think about the links between the graph of a derived function and the original function from which it was formed. The participants were asked to perform the following task: they were presented with four graphs that represented derived functions and from these graphs they were asked to construct the original functions from which they were formed. The students then had to walk these graphs as if they were displacement-time graphs. Their discussions were recorded on audio tape and their walks were captured using data logging equipment and these were analysed together with their pencil and paper notes. From these three sources of data, we were able to construct a picture of the students’ graphical understanding of connections in calculus. The results confirm that at the start of the activity the students demonstrate an algebraic symbolic view of calculus and find it difficult to make connections between the graphs of a derived function and the function itself. By being able to ‘walk’ an associated displacement time graph, we propose that the students are extending their understanding of calculus concepts from symbolic representation to a graphical representation and to what we term a ‘physical feel’. 相似文献
939.
Ma Wenxiu 《数学年刊B辑(英文版)》1997,18(1):79-88
WEAKCONVERGENCEFORNONUNIFORMφMIXINGRANDOMFIELDSLUCHUANRONGAbstractLet{ξt,t∈Zd}beanonuniformφmixingstrictlystationaryrea... 相似文献
940.
A simple one-step fully parallel trinary signed-digit arithmetic is proposed for parallel optical computing. This technique performs multidigit carry-free addition and borrow-free subtraction in constant time. The trinary signed-digit arithmetic operations are based on redundant bit representation of the digits. Optical implementation of the proposed arithmetic can be carried out using correlation or matrix multiplication based schemes. An efficient matrix multiplication based optical implementation that employs a fixed number of minterms for any operand length is developed. It is shown that only 30 minterms (less than recently reported techniques) are enough for implementing the one-step trinary addition and subtraction. 相似文献