Graphs on unlabelled nodes with a given number of edges

On the Number of Certain Subgraphs Contained in Graphs with a given Number of Edges

All graphs considered are finite, undirected, with no loops, no multiple edges and no isolated vertices. For two graphs G, H, let N(G, H) denote the number of subgraphs of G isomorphic to H. Define also, for l >=0, N(I,H)= max N(G, H), where the maximum is taken over all graphs G with l edges. We determine N(l, H) precisely for all l -> 0 when H is a disjoint union of two stars, and also when H...

The Asymptotic Number of Labeled Connected Graphs with a Given Number of Vertices and Edges

Let c(n, q) be the number of connected labeled graphs with n vertices and q 5 N = ( ) edges. Let x = q/n and k = q n. We determine functions w k 1 , a(x ) and cp(x) such that c (n , q) w k ( z ) e n r p ( x ) e o ( x ) uniformly for all n and q 2 n. If Q > O is fixed, n+= and 4q > ( 1 + ~ ) n log n, this formula simplifies to c(n, q) ( t ) exp(-ne-zq’n). On the other hand, if k = o(n”’), this f...

Ela on the Estrada Index of Graphs with given Number of Cut Edges

Let G be a simple graph with eigenvalues λ1, λ2, . . . , λn. The Estrada index of G is defined as EE(G) = ∑ n i=1 ei . In this paper, the unique graph with maximum Estrada index is determined among connected graphs with given numbers of vertices and cut edges.

On the Estrada index of graphs with given number of cut edges

Let G be a simple graph with eigenvalues λ1, λ2, . . . , λn. The Estrada index of G is defined as EE(G) = ∑ n i=1 ei . In this paper, the unique graph with maximum Estrada index is determined among connected graphs with given numbers of vertices and cut edges.

Preliminaries on the Asymptotic Number of H-free Labeled Connected Graphs with a given Number of Vertices and Edges