| 
 | 
 | 
Let 
 be an 
-Manifold and let 
 denote a Partition of 
 into
Disjoint path-connected Subsets.  Then if 
 is a Foliation of 
, 
each 
 is called a leaf and is not necessarily closed or compact.
See also Foliation
References
Rolfsen, D.  Knots and Links.  Wilmington, DE: Publish or Perish Press, p. 284, 1976.