The notion of an open collar is generalized to that of a
pseudo-collar. Important properties and examples are discussed. The main
result gives conditions which guarantee the existence of a pseudo-collar
structure on the end of an open n–manifold (n≥7). This paper may
be viewed as a generalization of Siebenmann's famous collaring theorem
to open manifolds with non-stable fundamental group systems at infinity.
Received: 30 July 1999
Revised: 8 December 2000
Accepted: 27 December 2000
Published: 27 December 2000
Proposed: Steve Ferry
Seconded: Robion Kirby, Cameron Gordon