Alexandr Prishlyak, Illia Ovtsynov

The Structure of Morse and Codimension One Gradient Flows on the Sphere with Holes

abstract:
We describe all possible topological structures of Morse flows and codimension one gradient flows generated by vector fields emerging in typical one-parameter bifurcations. Research is held on a 2-sphere with holes in the case where the number of singular points of flows is at most six.
For that purpose, we construct topological invariants of these flows which are actually the graphs endowed with certain information. In this case, they are separatrix skeletons and distinguished graphs of flows. For example, the saddle-node singularity is specified by selecting a separatrix in the skeleton of the flow before the bifurcation, whereas the saddle connection is specified by a separatrix which connects two saddles. Apart from that, we construct special codes for these graphs so that we can regain a skeleton and a graph from the code and thus recover the whole flow on a certain surface.

Mathematics Subject Classification: 37C10, 37C15, 37C20

Key words and phrases: Bifurcation, topological equivalence, structural stability, separatrix skeleton, saddle-node, saddle connection