On degree-sequence characterization and the extremal number of edges for various Hamiltonian properties under fault tolerance
Shih-Yan Chen, Shin-Shin Kao, Hsun Su
Abstract
Assume that n,δ,k are integers with 0 ≤k
< δ< n. Given a graph G=(V,E) with
|V|=n. The symbol G-F,
F⊆V, denotes the graph with V(G-F)=V-F,
and E(G-F) obtained by E after deleting the
edges with at least one endvertex in F. G
is called k-vertex fault traceable,
k-vertex fault Hamiltonian, or
k-vertex fault Hamiltonian-connected if
G-F remains traceable, Hamiltonian, and
Hamiltonian-connected for all F with 0≤|F|
≤k, respectively. The notations
h1(n,δ,k),
h2(n,δ,k), and
h3(n,δ,k) denote the minimum number of
edges required to guarantee an n-vertex graph with
minimum degree δ(G) ≥δ to be
k-vertex fault traceable, k-vertex fault
Hamiltonian, and k-vertex fault Hamiltonian-connected,
respectively. In this paper, we establish a theorem which uses the
degree sequence of a given graph to characterize the
k-vertex fault
traceability/hamiltonicity/Hamiltonian-connectivity, respectively.
Then we use this theorem to obtain the formulas for
hi(n,δ,k) for 1≤i ≤3,
which improves and extends the known results for k=0.
Full Text: PDF PostScript