Generalizations and strengthenings of Ryser's conjecture
Abstract
Ryser's conjecture says that for every -partite hypergraph with matching number , the vertex cover number is at most . This far reaching generalization of K\"onig's theorem is only known to be true for , or and . An equivalent formulation of Ryser's conjecture is that in every -edge coloring of a graph with independence number , there exists at most monochromatic connected subgraphs which cover the vertex set of . We make the case that this latter formulation of Ryser's conjecture naturally leads to a variety of stronger conjectures and generalizations to hypergraphs and multipartite graphs. Regarding these generalizations and strengthenings, we survey the known results, improving upon some, and we introduce a collection of new problems and results.
Keywords
Cite
@article{arxiv.2009.07239,
title = {Generalizations and strengthenings of Ryser's conjecture},
author = {Louis DeBiasio and Yigal Kamel and Grace McCourt and Hannah Sheats},
journal= {arXiv preprint arXiv:2009.07239},
year = {2021}
}
Comments
51 pages, 9 figures, 3 tables; v3: Updated in response to referee comments; v2: Fixed minor typos and updated/reorganized material in final section