a1 Department of Applied Mathematics Okayama University of Science 1-1 Ridai-cho, Okayama 700 Japan e-mail: email@example.com
The ordinary string class is an obstruction to lift the structure group LSpin(n) of a loop group bundle LQ → LM to the universal central extension of LSpin(n) by the circle. The vanishing problem of the ordinary string class and generalized string classes are considered from the viewpoint of the ring structure of the cohomology H*(M; R).
(Received October 05 1994)
(Revised January 05 1995)
1991 Mathematics subject classification (Amer. Math. Soc)