Let K be a knot manifold, that
is the 3-sphere Ss minus an open regular neighborhood of a polygonal simple closed
curve in ∕Ss. Whether K can be embedded in S8 differently or in a homotopy
3-sphere different from S8 (if such really exist) leads in a natural way to
the question of which planar surfaces can be embedded in K. Geometric
conditions are imposed on the embedded planar surfaces which are sufficient to
imply that K is not knotted, that is K is homeomorphic to a disk cross
S1.