KNOT-INEVITABLE PROJECTIONS OF PLANAR GRAPHS
Kouki Taniyama, Tatsuya Tsukamoto · Journal of Knot Theory and Its Ramifications · 1996
For each odd number n, we describe a regular projection of a planar graph such that every spatial graph obtained by giving it over/under information of crossing points contains a (2, n)-torus knot. We also show that for any spatial graph H, there is a regular projection of a (possibly nonplanar) graph such that every spatial graph obtained from it contains a subgraph that is ambient isotopic to H.