Mathematical logic seminar - Dec 3 2019

Time: 3:30pm - 4:30 pm

Room: Wean Hall 8220

Speaker:     Garrett Ervin    
CMU

Title: Realizing the ends of locally finite graphs

Abstract:

Suppose that G is an infinite, locally finite connected graph, and { e1, e2, … } is a countable dense subset of its space of ends. We prove that G3, the graph obtained from G by adding an edge between any two vertices of distance at most 3 from one another, can be partitioned into a family of one-sided infinite paths { p1, p2, … } such that pi converges to ei for every i. In particular, if G has only countably many ends, then G3 can be partitioned into a family of paths realizing each of its ends exactly once. This generalizes a result of Seward, that every connected graph of bounded degree with two ends is bi-Lipschitz equivalent to a graph with a bi-infinite Hamiltonian path.