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11.
Otfried Cheong Xavier Goaoc Andreas Holmsen Sylvain Petitjean 《Discrete and Computational Geometry》2008,39(1-3):194-212
We prove Helly-type theorems for line transversals to disjoint unit balls in ℝ
d
. In particular, we show that a family of n≥2d disjoint unit balls in ℝ
d
has a line transversal if, for some ordering ≺ of the balls, any subfamily of 2d balls admits a line transversal consistent with ≺. We also prove that a family of n≥4d−1 disjoint unit balls in ℝ
d
admits a line transversal if any subfamily of size 4d−1 admits a transversal.
Andreas Holmsen was supported by the Research Council of Norway, prosjektnummer 166618/V30. Otfried Cheong and Xavier Goaoc
acknowledge support from the French-Korean Science and Technology Amicable Relationships program (STAR). 相似文献
12.
Bosko Zivaljevic 《Transactions of the American Mathematical Society》1996,348(5):1921-1938
We continue the investigation of validity of Hall's theorem in the case of the Loeb space of an internal, uniformly distributed, hyperfinite measure space initiated in1992 by the author. Some new classes of graphs are introduced for which the measure theoretic version of Hall's theorem still holds.
13.
Xiangfei Ni 《Semigroup Forum》2009,78(1):34-53
The concept of quasi-adequate transversals is introduced. Some properties and characterizations for abundant semigroups with
a multiplicative quasi-adequate transversal are obtained. In particular, a structure theorem for such abundant semigroups
is given. Finally, some special cases are considered.
This research was partially supported by the National Natural Science Foundation of China (No. 10571077) and the Natural Science
Foundation of Gansu Province (No. 3ZS052-A25-017). 相似文献
14.
15.
We prove two results about the problem of finding the Helly number for line transversals to a family of parallel triangles in the plane: (1) If each three triangles of a family of parallel right triangles are intersected by an ascending (or a descending) line, then there is an ascending (or a descending) line that intersects all 相似文献
16.
设X_n={1,2,…,n}并赋予自然数序,MCK_n是X_n上核具有连续横截面保序或反序变换所构成的半群.K_n是MCK_n的最大正则子半群.本文将考虑K_n的理想K(n,r)={α∈K_n:|im(α)|≤r}(3≤r≤n-1).证明了K(n,r)的秩为(n-r+1)(n-r+2)(n-r+3)/6. 相似文献
17.
Francis Pastijn 《代数通讯》2017,45(11):4979-4991
Every regular band can be isomorphically embedded into a regular band which has a semilattice transversal. The latter constitute the variety of regular split bands, whose subvariety lattice is isomorphic to the lattice of regular band varieties. 相似文献
18.
Structure of the constitutive relations for hereditarily elastic materials reinforced by hard fibers
R. A. Kayumov I. G. Teregulov 《Journal of Applied Mechanics and Technical Physics》2005,46(3):405-411
The problem of simplifying the nonlinear hereditary elasticity relations is considered for strongly anisotropic materials
such as fiber-reinforced composites. This is done using their property that the material stiffness is high along the reinforcement
and is low in the cross-sectional direction. The material is considered transversally isotropic. The simplification is performed
by analyzing asymptotic representations of creep relations. Relations of various degrees of accuracy for various types of
composites and stress states are obtained.
__________
Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 46, No. 3, pp. 120–127, May–June, 2005. 相似文献
19.
M. N. Dmitriev N. M. Dmitriev V. V. Kadet M. N. Kravchenko S. G. Rassokhin 《Fluid Dynamics》2004,39(4):589-593
The results of an experimental determination of the relative phase permeabilities during flow of two immiscible fluids in stratified sandstone with transversally isotropic characteristics are presented. The measurements were performed on samples oriented in three directions: along, perpendicular to and at an angle of 45° to the stratification plane. An approximate solution of the problem of steady two-phase flow toward a finite gallery in an anisotropic porous medium for arbitrary relative orientation of the gallery and the principal axes of the absolute permeability tensor is given. This solution was tested against the experimental results. The good agreement between the theoretical and experimental results makes it possible to recommend for engineering calculations both the relations between the absolute and phase permeabilities for transversally isotropic and orthotropic porous media and the approximate solution obtained. 相似文献
20.
In this paper,the concept of right adequate transversals of rpp semigroups is introduced.We establish the structure of rpp semigroups with multiplicative right adequate transversals in terms of right normal bands and right adequate semigroups.In particular, some special cases are considered. 相似文献