Genus Distribution of Graph Amalgamations: Pasting at Root-Vertices

Abstract

We pursue the problem of counting the imbeddings of a graph in each of the orientable surfaces. We demonstrate how to achieve this for an iterated amalgamation of arbitrarily many copies of any graph whose genus distribution is known and further analyzed into a partitioned genus distribution. We introduce the concept of recombinant strands of face-boundary walks, and we develop the use of multiple production rules for deriving simultaneous recurrences. These two ideas are central to a broad-based approach to calculating genus distributions for graphs synthesized from smaller graphs.