1991 Mathematics Subject Classification. Primar y OO-XX , 92-XX .
ISBN 0-8218-0382-4
ISSN 1047-398X
Copying an d reprinting . Materia l i n this book ma y be reproduced b y any means for educationa l
and scientifi c purpose s withou t fe e o r permissio n wit h th e exceptio n o f reproductio n b y service s
that collec t fee s for delivery of documents an d provide d tha t th e customary acknowledgmen t o f th e
source is given. Thi s consent doe s not exten d t o other kind s of copying fo r general distribution , fo r
advertising o r promotiona l purposes , o r fo r resale . Request s fo r permissio n fo r commercia l us e o f
material shoul d b e addresse d t o th e Assistan t t o th e Publisher , America n Mathematica l Society ,
P. O. Bo x 6248 , Providence , Rhod e Islan d 02940-6248 . Request s ca n als o b e mad e b y e-mai l t o
reprint-permissionOams.org.
Excluded fro m thes e provision s i s material i n article s fo r whic h th e autho r hold s copyright . I n
such cases , request s fo r permissio n t o us e or reprin t shoul d b e addresse d directl y t o th e author(s) .
(Copyright ownershi p i s indicated i n th e notic e i n th e lowe r right-han d corne r o f th e firs t pag e o f
each article. )
© 1996 b y th e America n Mathematica l Society . Al l right s reserved .
The America n Mathematica l Societ y retain s al l right s
except thos e grante d t o th e Unite d State s Government .
Printed i n th e Unite d State s o f America .
@ Th e pape r use d i n thi s boo k i s acid-fre e an d fall s withi n th e guideline s
established t o ensur e permanenc e an d durability .
10 9 8 7 6 5 4 3 2 1 0 1 0 0 9 9 9 8 9 7 9 6
Previous Page Next Page