摘要(英) |
Let G be a graph. The unrestricted path number of G, denoted by
ho(G), is the minimum number of paths needed to cover the edges of G. The arboricity of G, denoted by a(G), is the minimum number of forests needed to decompose the edges of G. A linear forest is a forest in which each component is a path. The linear arboricity of G, denoted by la(G), is the minimum number of linear forests needed to decompose the edges of G. In Chapter 2, we study the linear arboricity and unrestricted path number of regular complete r-partite graphs. Let K_{r imes n} denote the complete r-partite graph such that each part has n$vertices, For rge 2, we obtain
a(K_{r imes n})= la(K_{r imes n})=
ho (K_{r imes n})=lceil frac{(r-1)n+1}{2}
ceil.
In Chapter 3, we study the linear arboricity of complete tripartite graphs. Suppose n_1ge n_2ge n_3, we obtain
la(K_{n_1, n_2, n_3})=n_1+1 if n_1=n_2=n_3, and
la(K_{n_1, n_2, n_3})=lceilfrac{n_1+n_2}{2}
ceil otherwise.
For a graph G and a positive integer k, let G^k denote the graph with V(G^k)=V(G) and E(G^k)={uv : u, vin V(G), u
e v, d_G(u, v)le k} where d_G(u, v) denotes the distance between u and v in G. We call G^k the k-th power of G.
A star forest is a forest in which each component is a star. The star arboricity of a graph G, denoted by sa(G), is the minimum number of star forests needed to decompose the edges of G. In Chapter 4, we study the star arboricity of power of cycles. Suppose that k, n are integers such that 2le kle lfloorfrac{n}{2}
floor-1, we obtain
sa(C_n^k)=k+1 if n=0(mod k+1), and
sa(C_n^k)=k+2 otherwise
In Chapter 5, some problems are proposed for further investigations. |
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