Winding Numbers on Surfaces II. Applications.
A Wirtinger presentation of a knot group is obtained from a diagram of the knot. T. Yajima showed that for a 2-knot or a closed oriented surface embedded in the Euclidean 4-space, a Wirtinger presentation of the knot group is obtained from a diagram in an analogous way. J. S. Carter and M. Saito generalized the method to non-orientable surfaces in 4-space by cutting non-orientable sheets of their diagrams by some arcs. We give a modification to their method so that one does not need to find and...
In this paper we estimate the crossing number of a flat vertex graph in 3-space in terms of the reduced degree of its Yamada polynomial.
For a knot with a strong inversion induced by an unknotting tunnel, we have a double covering projection branched over a trivial knot , where is the axis of . Then a set is called a -curve. We construct -curves and the cyclic branched coverings over -curves, having two non-isotopic Heegaard decompositions which are one stable equivalent.