arXiv subjects

Luke Postle

Publications and source records attributed to Luke Postle.

75 records · Page 5Linked to original sources

arXiv2014

Five-list-coloring graphs on surfaces I. Two lists of size two in planar graphs

Let G be a plane graph with outer cycle C, let u,v be vertices of C and let (L(x):x in V(G)) be a family of sets such that |L(u)|=|L(v)|=2, L(x) has at least three elements for every vertex x of C-{u,v} and L(x) has at least five elements for every vertex x of G-V(C). We prove a conjecture of Hutchinson that G has a (proper) coloring f such that f(x) belongs to L(x) for every vertex x of G. We will use this as a lemma in subsequent papers.

math.CO↗

arXiv2012

Five-coloring graphs on the Klein bottle

We exhibit an explicit list of nine graphs such that a graph drawn in the Klein bottle is 5-colorable if and only if it has no subgraph isomorphic to a member of the list.

math.CO↗

arXiv2011

Sub-exponentially many 3-colorings of triangle-free planar graphs

Thomassen conjectured that every triangle-free planar graph on n vertices has exponentially many 3-colorings, and proved that it has at least 2^[n^(1/12)/20000] distinct 3-colorings. We show that it has at least 2^sqrt(n/362) distinct 3-colorings.

math.CO↗