Unavoidable substructures in large and infinite $2$-edge-connected graphs

Abstract

In 1930, Ramsey proved that every large graph contains either a large clique or a large edgeless graph as an induced subgraph. It is well known that every large connected graph contains a long path, a large clique, or a large star as an induced subgraph. Recently Allred, Ding, and Oporowski presented the unavoidable large induced subgraphs for large and infinite $2$-connected graphs. The $2$-edge-connected (sometimes called bridgeless) graphs form an important class between connected graphs and $2$-connected graphs. In this paper we describe the unavoidable large induced subgraphs for large and infinite $2$-edge-connected graphs. Ubiquitous structures in $2$-edge-connected graphs that we call `chains of pinched super-clean ladders' play an important role in these descriptions. As consequences we obtain results on unavoidable large subgraphs, topological minors, minors, induced topological minors, induced minors, and Eulerian subgraphs in large and infinite $2$-edge-connected graphs. When appropriate we extend our results to multigraphs.

17 pages, 6 figures; revised title, some material moved into an appendix