A codimension one foliation of a 3-manifold
is said to be taut if for every leaf
in the leaf space
of
, there is a circle
transverse to
(i.e., a closed loop transverse
to the tangent field of
) which intersects
.
Taut foliations play a significant role in various aspects of topology and are credited as being one of two major tools (along with incompressible surfaces) responsible for revealing significant topological and geometric information about 3-manifolds (Gabai and Oertel 1989). As such, a considerable amount of research has gone into the study of taut foliations on 3-manifolds. One well-known result is that every taut foliation is necessarily Reebless and that, for any non-taut Reebless foliation, the leaves which don't admit a closed transversal are necessarily tori. Additionally, the closed leaves of a taut foliation are homologically nontrivial.
Some classification results for taut foliations are also known. One such result, attributed by Eliashberg and Thurston to Novikov and Sullivan, says that a foliation
on a closed
3-manifold
is taut if it is different from the foliation
on
and satisfies any one of the following:
1. Each leaf
of
is intersected by a transversal closed curve.
2. There exists a vector field on
which is transversal to
and preserves a volume form
on
.
3.
admits a Riemannian metric for which all leaves
are minimal surfaces.
Moreover, a necessary and sufficient condition for tautness of a foliation is that
contain no generalized
Reeb components (Goodman 1975).