Let f : M → Rp be a
smooth map of a closed n-dimensional manifold M into Rp(n ≥ p) which has only
definite fold singularities as its singular points. Such a map is called a specialgeneric map, which was first defined by Burlet and de Rham for (n,p) = (3,2)
and later extended to general (n,p) by Porto, Furuya, Sakuma and Saeki.
In this paper, we study the global topology of such maps for p = 3 and
give various new results, among which are a splitting theorem for manifolds
admitting special generic maps into R3 and a classification theorem of 4- and
5-dimensional manifolds with free fundamental groups admitting special generic maps
into R3. Furthermore, we study the topological structure of the surfaces
which arise as the singular set of a special generic map into R3 on a given
manifold.