Many flows in the group connectivity setting
Abstract
Two well-known results in the world of nowhere-zero flows are Jaeger's 4-flow theorem asserting that every 4-edge-connected graph has a nowhere-zero -flow and Seymour's 6-flow theorem asserting that every 2-edge-connected graph has a nowhere-zero -flow. Dvo\v{r}\'ak and the last two authors of this paper extended these results by proving the existence of exponentially many nowhere-zero flows under the same assumptions. We revisit this setting and provide extensions and simpler proofs of these results. The concept of a nowhere-zero flow was extended in a significant paper of Jaeger, Linial, Payan, and Tarsi to a choosability-type setting. For a fixed abelian group , an oriented graph is called -connected if for every function there is a flow with for every (note that taking forces to be nowhere-zero). Jaeger et al. proved that every oriented 3-edge-connected graph is -connected whenever . We prove that there are exponentially many solutions whenever . For the group we prove that for every oriented 3-edge-connected with and every , there are at least flows with for every .
Keywords
Cite
@article{arxiv.2005.09767,
title = {Many flows in the group connectivity setting},
author = {Matt DeVos and Rikke Langhede and Bojan Mohar and Robert Šámal},
journal= {arXiv preprint arXiv:2005.09767},
year = {2020}
}
Comments
19 pages