Counting two-graphs related to trees
type: Item
instance of: scholarly article
title: Counting two-graphs related to trees
zbMATH Open document ID: 0810.05031
author: Peter J. Cameron
published in: The Electronic Journal of Combinatorics
publication date: 1995-02-09T00:00:00Z
full work available at URL: https://eudml.org/doc/118557
full work available at URL: R4
review text: Summary: In an earlier paper, I showed that the classes of pentagon-free two- graphs and of pentagon-and-hexagon-free two-graphs could be represented in terms of trees. This paper gives formulae for the numbers of labelled objects in each of these classes, as well as the numbers of labelled reduced two-graphs in each class. The proofs use various enumeration results for trees. At least some of these results are well known. To make the paper self-contained, I have included proofs.
Mathematics Subject Classification ID: 05C30
Mathematics Subject Classification ID: 05C05
zbMATH DE Number: 721223
zbMATH Keywords: two-graphs
zbMATH Keywords: enumeration
zbMATH Keywords: trees
MaRDI profile type: Publication
description: scientific article; zbMATH DE number 721223