Download Geometry and Algebra of Multidimensional Three-Webs by Maks A. Akivis, Alexander M. Shelekhov (auth.) PDF

By Maks A. Akivis, Alexander M. Shelekhov (auth.)

'The ebook is warmly urged to everybody doing study within the similar fields.'Deutschen Mathematiker-Vereinigung 97:21 1993

Show description

Read or Download Geometry and Algebra of Multidimensional Three-Webs PDF

Best geometry books

Geometry of Homogeneous Bounded Domains

S. G. Gindikin, I. I. Pjateckii-Sapiro, E. B. Vinberg: Homogeneous Kähler manifolds. - S. G. Greenfield: Extendibility houses of actual submanifolds of Cn. - W. Kaup: Holomorphische Abbildungen in Hyperbolische Räume. - A. Koranyi: Holomorphic and harmonic features on bounded symmetric domain names. - J.

Discontinuous Groups of Isometries in the Hyperbolic Plane

This e-book through Jakob Nielsen (1890-1959) and Werner Fenchel (1905-1988) has had
a lengthy and intricate background. In 1938-39, Nielsen gave a sequence of lectures on
discontinuous teams of motions within the non-euclidean aircraft, and this led him - in the course of
World conflict II - to jot down the 1st chapters of the e-book (in German). while Fenchel,
who needed to get away from Denmark to Sweden as a result of German profession,
returned in 1945, Nielsen initiated a collaboration with him on what turned identified
as the Fenchel-Nielsen manuscript. at the moment they have been either on the Technical
University in Copenhagen. the 1st draft of the Fenchel-Nielsen manuscript (now
in English) was once entire in 1948 and it was once deliberate to be released within the Princeton
Mathematical sequence. even though, end result of the swift improvement of the topic, they felt
that gigantic alterations needed to be made earlier than booklet.
When Nielsen moved to Copenhagen college in 1951 (where he stayed until eventually
1955), he was once a lot concerned with the foreign association UNESCO, and the
further writing of the manuscript used to be left to Fenchel. The documents of Fenchel now
deposited and catalogued on the division of arithmetic at Copenhagen Univer-
sity include unique manuscripts: a partial manuscript (manuscript zero) in Ger-
man containing Chapters I-II (

I -15), and an entire manuscript (manuscript I) in
English containing Chapters I-V (

1-27). The records additionally comprise a part of a corre-
spondence (first in German yet later in Danish) among Nielsen and Fenchel, the place
Nielsen makes precise reviews to Fenchel's writings of Chapters III-V. Fenchel,
who succeeded N. E. Nf/Jrlund at Copenhagen college in 1956 (and stayed there
until 1974), used to be a great deal concerned with a radical revision of the curriculum in al-
gebra and geometry, and targeted his learn within the conception of convexity, heading
the foreign Colloquium on Convexity in Copenhagen 1965. for nearly twenty years
he additionally positioned a lot attempt into his task as editor of the newly began magazine Mathematica
Scandinavica. a lot to his dissatisfaction, this task left him little time to complete the
Fenchel-Nielsen undertaking the way in which he desired to.
After his retirement from the collage, Fenchel - assisted by means of Christian Sieben-
eicher from Bielefeld and Mrs. Obershelp who typed the manuscript - came across time to
finish the booklet basic Geometry in Hyperbolic area, which used to be released by means of
Walter de Gruyter in 1989 almost immediately after his loss of life. at the same time, and with a similar
collaborators, he supervised a typewritten model of the manuscript (manuscript 2) on
discontinuous teams, removal a few of the imprecise issues that have been within the unique
manuscript. Fenchel instructed me that he reflected elimination components of the introductory
Chapter I within the manuscript, considering that this may be coated through the booklet pointed out above;
but to make the Fenchel-Nielsen e-book self-contained he eventually selected to not do
so. He did choose to pass over
27, entitled Thefundamental team.

As editor, i began in 1990, with the consent of the criminal heirs of Fenchel and
Nielsen, to provide a TEX-version from the newly typewritten model (manuscript 2).
I am thankful to Dita Andersen and Lise Fuldby-Olsen in my division for hav-
ing performed an excellent activity of typing this manuscript in AMS- TEX. i've got additionally had
much support from my colleague J0rn B0rling Olsson (himself a scholar of Kate Fenchel
at Aarhus college) with the facts analyzing of the TEX-manuscript (manuscript three)
against manuscript 2 in addition to with a common dialogue of the difference to the fashion
of TEX. In such a lot respects we determined to keep on with Fenchel's intentions. despite the fact that, turning
the typewritten variation of the manuscript into TEX helped us to make sure that the notation,
and the spelling of yes key-words, will be uniform in the course of the publication. additionally,
we have indicated the start and finish of an evidence within the ordinary sort of TEX.
With this TEX -manuscript I approached Walter de Gruyter in Berlin in 1992, and
to my nice reduction and pride they agreed to submit the manuscript of their sequence
Studies in arithmetic. i'm so much thankful for this confident and quickly response. One
particular challenge with the e-book became out to be the copy of the various
figures that are an essential component of the presentation. Christian Siebeneicher had at
first agreed to bring those in ultimate digital shape, yet via 1997 it turned transparent that he
would now not be capable of locate the time to take action. notwithstanding, the writer provided an answer
whereby I may still bring exact drawings of the figures (Fenchel didn't depart such
for Chapters IV and V), after which they'd set up the creation of the figures in
electronic shape. i'm very thankful to Marcin Adamski, Warsaw, Poland, for his high-quality
collaboration about the genuine construction of the figures.
My colleague Bent Fuglede, who has personaHy identified either authors, has kindly
written a brief biography of the 2 of them and their mathematical achievements,
and which additionally locations the Fenchel-Nielsen manuscript in its right standpoint. In
this connection i need to thank The Royal Danish Academy of Sciences and
Letters for permitting us to incorporate during this publication reproductions of pictures of the 2
authors that are within the ownership of the Academy.
Since the manuscript makes use of a couple of designated symbols, an inventory of notation with brief
explanations and connection with the particular definition within the booklet has been incorporated. additionally,
a accomplished index has been extra. In either instances, all references are to sections,
not pages.
We thought of including an entire checklist of references, yet determined opposed to it because of
the overwhelming variety of examine papers during this zone. as an alternative, a miles shorter
list of monographs and different complete money owed appropriate to the topic has been
collected.
My ultimate and such a lot honest thank you visit Dr. Manfred Karbe from Walter de Gruyter
for his commitment and perseverance in bringing this book into life.

Statistics on Special Manifolds

This ebook is worried with statistical research at the distinct manifolds, the Stiefel manifold and the Grassmann manifold, taken care of as statistical pattern areas inclusive of matrices. the previous is represented via the set of m x ok matrices whose columns are jointly orthogonal k-variate vectors of unit size, and the latter by means of the set of m x m orthogonal projection matrices idempotent of rank ok.

Additional resources for Geometry and Algebra of Multidimensional Three-Webs

Sample text

The leaves of the web W are autoparallel submanifolds relative to each connection of the pencil,(W) (cf. 97». 18. A vector field ~ = (~L~~), given in a manifold X carrying a web W = (X,A",), is called Segrean if at any point p E X a vector ~(p) belong to the Segre cone, defined at the point p. Prove that (i) A field ~ is Segrean if and only if ~; : A~f; and (ii) Any Segrean field ~ defines in X a unique distribution of two-dimensional transversal subspaces, containing ~; and (iii) If a Segrean field ~ : (~L A~D is parallel along a curve " then AI")': const.

1,2 ,3 , and W a , Wap, Wap"Y are partial derivatives of the function W(UI,U2,U3). Use this formula to compute the curvature of the web from Problem 5. 13. 125) Solution. 51), we set = dx l _ x 3y3dx 2 _ y3(x 2 + y2)dx 3 , wI = dyl _ x 3 y 3dy2 _ x 3(x 2 + y2)d y 3, 2 w 2 = dx 2, w 3 = dx 3 , w 2 = dy2, w 3 = dy3. 127) where we denote 44 1. THREE-WEBS AND GEOMETRIC STRUCTURES ASSOCIATED WITH THEM w~ wl : X3W3 + y3w3 : x 3dy3 + y3dx 3 : d(X 3y3), 2 1 : y3dy2 + x 3dx 2 + (X 2 + y2)(dx 3 + dy3) : d(X 2X3) + d(y2 y3) + x 2dy3 + y 2dx 3.

A respectively (see, for example, [KN 63], vol. 1, p. 1 The term "three-web" was introduced by Blaschke [BB 38], and the term "quasigroup" was introduced by Moufang. 2. As proved in [DJ 85], the differential-geometric equivalence of smooth three-webs follows from their topological equivalence. 4. 32), they were found by Akivis [A 69b]. These equations also can be considered as the structure equations ofthe coordinate quasigroup q12 of a web. As such, they generalize the Maurer-Cartan equations of a Lie group.

Download PDF sample

Rated 4.38 of 5 – based on 46 votes