ON 3-COLORING OF CHAINS AND PROPELLERS
摘要
A chain is a tree where two vertices have degree 1 and all others have degree 2. A propeller is a tree that has one vertex of degree 3, three vertices of degree 1, and all other vertices have degree 2. A proper propeller is a propeller, where vertices of degree one are at equal distances from the vertex of degree 3. We study the following problem: how to find the number of 3-colorings of a chain and a proper propeller in the case where the numbers of vertices of each color are given? In both cases, generating functions are presented.