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951.
A subset S of a d-dimensional convex body K is extensive if S
∂K and for any p, q ∈ S the distance between p and q is at least one-half of the maximum length of chords of K parallel to the segment pq. In this paper we establish the general upper bound |S| ≤ 3
d
— 1. We also find an upper bound for a certain class of 3-polytopes, which leads to the determination of the maximum cardinalities
of extensive subsets and their extremal configurations for tetrahedra, octahedra and some other 3-polytopes.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
952.
Daoxing Xia 《Integral Equations and Operator Theory》1999,33(4):489-506
This paper studies the class of pure operatorsA on a Hilbert space
satisfying dimK
A
<, where
. The main tool is a pair of matrices
and
. A reproducing kernel Hilbert space model is introduced for a subclass of this class of operators. Some theorems are established for some subnormal operators as well as hyponormal operators in this class. 相似文献
953.
We present several results concerning the asymptotic behavior of (random) infinite products of generic sequences of positive linear operators on an ordered Banach space. In addition to a weak ergodic theorem we also obtain convergence to an operator of the formf(·) wheref is a continuous linear functional and is a common fixed point. 相似文献
954.
Christian Mazza 《Probability Theory and Related Fields》1999,113(2):171-190
We consider the ±J spin glass on a finite graph G=(V,E), with i.i.d. couplings. Our approach considers the Z
2 local gauge invariance of the system. We see the gauge group as a graph theoretic linear code ? over GF(2). The gauge is fixed by choosing a convenient linear supplement of ?. Assuming some relation between the disorder parameter
p and the inverse temperature of the thermal bath β
pb
, we study percolation in the random interaction random cluster model, and extend the results to dilute spin glasses.
Received: 5 May 1997 / Revised version: 9 April 1998 相似文献
955.
Bernard Badzioch 《K-Theory》1999,16(1):29-34
We prove that for an arbitrary endomorphism of a ring R the group K1(R[t]) splits into the direct sum of K1(R) and Ñil (r;). Moreover, for any such R and Ñil (R; ) is isomorphic to Ñil (R ; ) for some ring R with : R R – an isomorphism. 相似文献
956.
On the stability of wavelet and Gabor frames (Riesz bases) 总被引:6,自引:0,他引:6
Zhang Jing 《Journal of Fourier Analysis and Applications》1999,5(1):105-125
If the sequence of functions j, k is a wavelet frame (Riesz basis) or Gabor frame (Riesz basis), we obtain its perturbation system j,k which is still a frame (Riesz basis) under very mild conditions. For example, we do not need to know that the support of or
is compact as in [14]. We also discuss the stability of irregular sampling problems. In order to arrive at some of our results, we set up a general multivariate version of Littlewood-Paley type inequality which was originally considered by Lemarié and Meyer [17], then by Chui and Shi [9], and Long [16]. 相似文献
957.
Olaf Bröcker 《Journal of Geometry》2002,75(1-2):46-60
For M?bius planes Schaeffer [9] has proved that all seven
point degenerations of Miquel's Theorem characterize miquelian M?bius
planes. For Laguerre planes we have several degenerations of Miquel's
Theorem with eight and seven points. We prove that all except one of
these degenerations characterize miquelian Laguerre planes. The
remaining degeneration characterizes elation Laguerre planes.
Received 14 September 2001; revised 1 September 2002. 相似文献
958.
碲钨杂多酸—丁基罗丹明B超高灵敏显色反应的研究 总被引:5,自引:0,他引:5
聚乙烯醇存在下,碲与钨酸钠形成碲钨杂多酸,继而丁基罗丹明B形成离子缔合物。 相似文献
959.
Paul Sablonnière 《Numerical Algorithms》1992,2(3):241-254
Applying the generalized Euler transform to the firstn partial sums of a power series results in a triangular array whose inferior diagonal givesn approximate values of the sum of this series. The aim of this short note is to estimate the best of thesen values and to compare it with the actual best one for a collection of test series. 相似文献
960.