Rotation numbers for unions of circuits


Let G be a simple undirected graph which has p vertices and is rooted at x. Informally, the rotation number h(G, x) of this rooted graph is the minimum number of edges in a p‐vertex graph F, such that for each vertex v of F, there exists a copy of G in F with the root x at v. In this paper, we calculate a lower bound for the rotation number of the graph which is the disjoint union of circuits Ck, Ce where 4 ⩽ k < ⩽, give infinite classes where this bound is exact, and obtain classes of rotation numbers for the case k = 4. Copyright © 1984 Wiley Periodicals, Inc., A Wiley Company

Publication Title

Journal of Graph Theory