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61.
We investigate the structure of a collineation groupG preserving an oval in a finite projective plane of odd order and we obtain several results aboutG, whenG is a2-group. These results are then used to investigate the structure ofG/O(G) in the general case and, in particular, that ofF*(G/O(G)).This research was supported in part by a grant from the M.U.R.S.T. 相似文献
62.
It is shown that the axiom For any points x, y, z such that y is between x and z, there is a right triangle having x and z as endpoints of the hypotenuse and y as foot of the altitude to the hypotenuse, when added to three-dimensional Euclidean geometry over arbitrary ordered fields, is weaker than the axiom Every line which passes through the interior of a sphere intersects that sphere. 相似文献
63.
We give a characterization of the boundaries of holomorphic chains in complex projective space. This extends previous work
of the authors and complements results of Dolbeault and Henkin. 相似文献
64.
Mowaffaq Hajja 《Journal of Geometry》2005,83(1-2):46-56
In contrast with the analogous situation for a triangle, the cevians that join the vertices of a tetrahedron to the points
where the faces touch the insphere (or the exspheres) are not concurrent in general. This observation led the present author
and P. Walker in [4] to devise alternative definitions of the Gergonne and Nagel centers of a tetrahedron that do not assume
the concurrence of such cevians and that coincide with the ordinary definitions in the case of a triangle. They then proved
that the Gergonne center exists and is unique for all tetrahedra and that the Nagel center, though unique, exists only for
tetrahedra that satisfy certain conditions. In this article, we extend these definitions to simplices of any dimension. By
keeping the requirement that the Gergonne center be interior and relaxing such a condition for the Nagel center, we prove
that both centers exist and are unique for all simplices, thus polishing the definitions and generalizing the results of the
above-mentioned article. 相似文献
65.
We relate the semiclassical asymptotics of the 6j symbols for the quantized enveloping algebra
at q a root of unity (resp. q real positive) to the geometry of spherical (resp. hyperbolic) tetrahedra. 相似文献
66.
Yurij M. Berezansky Eugene W. Lytvynov Artem D. Pulemyotov 《Integral Equations and Operator Theory》2005,53(2):191-208
By definition, a Jacobi field
is a family of commuting selfadjoint three-diagonal operators in the Fock space
The operators J(ϕ) are indexed by the vectors of a real Hilbert space H+. The spectral measure ρ of the field J is defined on the space H− of functionals over H+. The image of the measure ρ under a mapping
is a probability measure ρK on T−. We obtain a family JK of operators whose spectral measure is equal to ρK. We also obtain the chaotic decomposition for the space L2(T−, dρ K). 相似文献
67.
Helena ?migoc 《Linear and Multilinear Algebra》2013,61(2):85-96
This article presents a technique for combining two matrices, an n?×?n matrix M and an m?×?m matrix B, with known spectra to create an (n?+?m???p)?×?(n?+?m???p) matrix N whose spectrum consists of the spectrum of the matrix M and m???p eigenvalues of the matrix B. Conditions are given when the matrix N obtained in this construction is nonnegative. Finally, these observations are used to obtain several results on how to construct a realizable list of n?+?1 complex numbers (λ1,λ2,λ3,σ) from a given realizable list of n complex numbers (c 1,c 2,σ), where c 1 is the Perron eigenvalue, c 2 is a real number and σ is a list of n???2 complex numbers. 相似文献
68.
Bernd Schomburg 《Linear algebra and its applications》2011,434(1):356-360
We give a necessary and sufficient group theoretic condition for a Cayley digraph to be primitive. 相似文献
69.
This paper aims to present the generalized Kudryashov method to find the exact traveling wave solutions transmutable to the solitary wave solutions of the ubiquitous unsteady Korteweg–de Vries equation and its two famed alternatives, namely, the regularized long‐wave equation and the time regularized long‐wave equation. The exact analytic solutions of the studied equations are constructed explicitly in three forms, namely, hyperbolic, trigonometric, and rational function. The validity of our solutions is verified with MAPLE by putting them back into the original equation and found correct. Moreover, it has shown that the generalized Kudryashov method is an easy and reliable technique over the existing methods. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
70.
Eike Hertel 《Geometriae Dedicata》1994,52(3):215-220
A subsetS of a metric space (X,d) is calledd-convex if for any pair of pointsx,y S each pointz X withd(x,z) +d(z,y) =d(x,y) belongs toS. We give some results and open questions concerning isometric and convexity-preserving embeddings of finite metric spaces into standard spaces and the number ofd-convex sets of a finite metric space. 相似文献