摘要:

Two methods for looking at cosmological density on large scales are briefly described. The first takes galaxies observed in infrared, by the IRAS satellite. The second method, called POTENT by its inventors (Dekel and Bertschinger), uses the observed peculiar motions of galaxies to find the large scale peculiar velocity field. These two methods can be combined to test various theories of structure formation. First, though, we need to make sure that the velocity field derived from POTENT is consistent with the fractional overdensity field derived from IRAS. One way to compare them employs the non-parametric Wilcoxon-Mann-Whitney test.

ISSN:1607-3606    

DOI:10.1080/16073606.1996.9631841

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

LetDbe a digraph. The arc (u, v) is adjacent to the arc (w, x) ifv = w. Letr(D) be the smallest number of arc colors so that no two adjacent arcs have the same color. LetGbe the underlying graph ofDand letx(G) be its usual chromatic number. We extend a lower bound of Lovász forr(D) by proving that

ISSN:1607-3606    

DOI:10.1080/16073606.1996.9631842

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

We introduce a new large class of semigroupsSincluding all locally finite, completely regular and strongly π-regular linear semigroups. For any semigroupSin the class and anyS-graded ringR, the structure of the Jacobson radical ofRis reduced to the radicals of subrings graded by the maximal subgroups ofS. Many results on radicals follow from this reduction in a unified way. In two special cases the reduction is simplified.

ISSN:1607-3606    

DOI:10.1080/16073606.1996.9631843

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

In this paper we show that a Banach-Dieudonné type theorem for the space of entire functions of bounded type on a Banach space only holds in the finite dimensional case. We also study if this result holds in the setting of Fréchet spaces.

ISSN:1607-3606    

DOI:10.1080/16073606.1996.9631844

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

ISSN:1607-3606    

DOI:10.1080/16073606.1996.9631845

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

Semi-infinite block Toeplitz operators with rational matrix symbols are inverted explicitly by employing the factorization method. All formulas are based on a special representation of the symbol involving a quintet of matrices, which differs from the ones that have been used earlier.

ISSN:1607-3606    

DOI:10.1080/16073606.1996.9631846

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

This paper investigates torsion-free abelian groupsAwhich areQE-flat, i.e. for whichQAis flat as anQE(A)-module. It is shown that a torsion-freeAhas this property iff Tor1(M, A)is torsion for all rightE(A)-modulesM. Furthermore, a torsion-free group of rank 4 is constructed which isQE-flat but not quasi-isomorphic to anE-flat group. This gives a negative response to a question of R. Pierce. The paper concludes with a discussion of the structure of torsion-free groups of finite rank which areQE-flat.

ISSN:1607-3606    

DOI:10.1080/16073606.1996.9631847

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

ISSN:1607-3606    

DOI:10.1080/16073606.1996.9631848

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

ISSN:1607-3606    

DOI:10.1080/16073606.1996.9631820

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor