The Relation of Cobordism to K-Theories

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P. E. Conner · E. E. Floyd University of Virginia, Charlottesville

The Relation of Cobordism to K-Theories 1966

Springer-Verlag· Berlin· Heidelberg· New York

All rights, especially that of translation into foreign languages, reserved. It is also forbidden to reproduce this book, either whole or in part, by photomechanical means (photostat, microfilm and/or microcard) or by other procedure without written permission from Springer Verlag. (l:) by Springer-Verlag Berlin' Heidelberg 1966. Library of Congress Catalog Card Number 66-30143. Printed in Germany. Title No. 7348.

INTRODUCTION These lectures treat certain topics relating K-theory and cobordism. Since new connections are in the process of being discovered by various workers, we make no attempt to be definitive but simply cover a few of our favorite topics.

If there is any unified theme it is that we treat

various generalizations of the Todd genus. In Chapter I we treat the Thom isomorphism in K-theory.

The

families U, SU, Sp of unitary, special unitary, symplectic groups generate spectra MU, MSU, MSp of Thom spaces.

In the fashion of

G. W. Whitehead [26J, each spectrum generates a generalized cohomology theory and a generalized homology theory.

The cohomology theories are

a (.)

* denoted by.a * (.), £). * (.), and are called cobordism theories; U SU Sp U SU Sp the homology theories are denoted by {}. (.), 1l. (.), fl (.) and are called bordism theories.

n

*

*

*

The coefficient groups are, taking one case

a Un = .()..nu

as an example, given by un = 11 un (point), U U n related by..o = 11 u- • Moreover.o. is just n n bordism classes [MnJ of closed weakly almost

(point) and are

the bordism group of all complex manifolds Mn ,

similarly forll SU andll. SP. on the other hand there are the n n Grothendieck-Atiyah-Hirzebruch periodic cohomology theories K* (·),KO *

of K-theory.

The main point of Chapter I, then, is to

define natural transformations

-+

KO*(.)

: 0. *{.) -4

K*(.)

!"': I1

*(.)

SU

U

of cohomology theories.

Such transformations have been folk theorems

since the work of Atiyah-Hirzebruch [6], Dold [13], and others.

It

should be noted that on the coefficient groups, 1\

fV c

:Jr..L.

-2n U

-2n

K

lpt)

is identified up to sign with the Todd genus Td

=z

. .0. U

z.

2n In Chapter II we show among other things that the cobordism

theories determine the K-theories. ring

For example,

Z and makes Z into

generates a

c

It is

shown that K* (X,A)

as Z2-graded modules. KO * l·).

.0..* lX,A)@ .0 * U

U

Z

Similarly symplectic cobordism determines

The isomorphisms are generated by

t"c' F

respectively.

Various topics are treated along the way, in particular cobordism characteristic classes. There is the sphere 1\

framed bordism

J is nembedded

lPoint)

n The spectrum form

MUI 4.

=

whose homology groups are the fr

l·).

The coefficient group

are just the stable stems 7T

n+k in a natural way in MU, and one can thus

In Chapter III we s tudy the group

.0. u, fr = 7T

=

[-:

if Y

=X

if Y = -X otherwis