Semester
Spring
Date of Graduation
2008
Document Type
Dissertation
Degree Type
PhD
College
Eberly College of Arts and Sciences
Department
Mathematics
Committee Chair
Hong-Jian Lai.
Abstract
A circuit is a connected 2-regular graph. A cycle is a graph such that the degree of each vertex is even. A graph G is Hamiltonian if it has a spanning circuit, and Hamiltonian-connected if for every pair of distinct vertices u, v ∈ V( G), G has a spanning (u, v)-path. A graph G is s-Hamiltonian if for any S ⊆ V (G) of order at most s, G -- S has a Hamiltonian-circuit, and s-Hamiltonian connected if for any S ⊆ V( G) of order at most s, G -- S is Hamiltonian-connected. In this dissertation, we investigated sufficient conditions for Hamiltonian and Hamiltonian related properties in a graph or in a line graph. In particular, we obtained sufficient conditions in terms of connectivity only for a line graph to be Hamiltonian, and sufficient conditions in terms of degree for a graph to be s-Hamiltonian and s-Hamiltonian connected.;A cycle C of G is a spanning eulerian subgraph of G if C is connected and spanning. A graph G is supereulerian if G contains a spanning eulerian subgraph. If G has vertices v1, v2, &cdots; ,vn, the sequence (d( v1),d(v2), &cdots; ,d(vn)) is called a degree sequence of G. A sequence d = ( d1,d2, &cdots; ,dn) is graphic if there is a simple graph G with degree sequence d. Furthermore, G is called a realization of d. A sequence d ∈ G is line-hamiltonian if d has a realization G such that L(G) is hamiltonian. In this dissertation, we obtained sufficient conditions for a graphic degree sequence to have a supereulerian realization or to be line hamiltonian.;In 1960, Erdos and Posa characterized the graphs G which do not have two edge-disjoint circuits. In this dissertation, we successfully extended the results to regular matroids and characterized the regular matroids which do not have two disjoint circuits.
Recommended Citation
Zhou, Ju, "Cycles in graph theory and matroids" (2008). Graduate Theses, Dissertations, and Problem Reports. 2720.
https://researchrepository.wvu.edu/etd/2720
