MathDB
Quasicolorable coloring of a graph

Source: HMIC 2022/4

April 8, 2022
graph theorycombinatorics

Problem Statement

Call a simple graph GG quasicolorable if we can color each edge blue, red, green, or white such that
[*] for each vertex v of degree 3 in G, the three edges incident to v are either (1) red, green, and blue, or (2) all white, [*] not all edges are white.
A simple connected graph GG has aa vertices of degree 44, bb vertices of degree 33, and no other vertices, where aa and bb are positive integers. Find the smallest real number cc so that the following statement is true: “If a/b>ca/b > c, then GG must be quasicolorable.”