The structure of automorphisms of real suspension flows

This paper is motivated by the connections between automorphisms of real suspension flows and 2 suspension actions. Automorphisms which naturally lead to 2-cocyles are examined from the viewpoint of covering theory in terms of an associated cylinder flow. A natural type of automorphisms (called simple) is analyzed via ergodic methods. It is shown that all automorphisms of suspensions built over minimal rotations on tori satisfy this condition. A more general approach using eigenfunctions extends this result to minimal affines, Furstenberg-type distal flows, certain nilmanifolds and a class of non-distal flows on the 2-torus. © 1991, Cambridge University Press. All rights reserved.