Strongly hopfian manifolds as codimension-2 fibrators

If a closed n-manifold N has a 2-1 covering, we consider the covering space N of N corresponding to H, where H is the intersection of all subgroups H-i of index 2 in pi(1)(N), i.e., H = boolean AND(i is an element of I) H-i with [pi(1)(N) : H-i] = 2 for i is an element of I. We will show that if pi(1)(N) is residually finite, chi(N) not equal 0, and (N) over tilde is hopfian, then N is a codimension-2 fibrator. And then, we will also get several results about codimension-2 fibrators as its corollaries. (C) 1999 Elsevier Science B.V. All rights reserved.