A sufficient condition guaranteeing large cycles in graphs

A new sufficient condition for hamiltonian graphs

The study of Hamiltonian graphs began with Dirac’s classic result in 1952. This was followed by that of Ore in 1960. In 1984 Fan generalized both these results with the following result: If G is a 2-connected graph of order n and max{d(u), d(v)}≥n/2 for each pair of vertices u and v with distance d(u, v)=2, then G is Hamiltonian. In 1991 Faudree–Gould–Jacobson–Lesnick proved that if G is a 2-co...

A sufficient condition for Hamilton cycles in bipartite tournaments

A sufficient condition for Hamiltonian cycles in bipartite tournaments

We prove a new sufficient conditi()n on degrees for a bipartite tournament to be Hamiltonian, that is, if an n x n bipartite tournament T satisfies the condition dT(u) + dj;(v) ~ n 1 whenever uv is an arc of T, then T is Hamiltonian, except for two exceptional graphs. This result is shown to be best possible in a sense. T(X, Y, E) denotes a bipartite tournament with bipartition (X, Y) and verte...

A condition Guaranteeing Commutativity

We give a simple characterization for a nonassociative algebra A, having characteristic 6= 2, to be commutative. Namely, A is commutative if and only if it is exible with a commuting set of generators. A counterexample shows that characteristic 6= 2 is necessary. Both the characterization and the counterexample were discovered using the computer algebra system in [2].

New sufficient condition for Hamiltonian graphs

Let G be a graph and α(G) be the independence number of G. For a vertex v ∈ V (G), d(v) and N(v) represent the degree of v and the neighborhood of v in G, respectively. In this paper, we prove that if G is a k-connected graph of order n, and if max{d(v) : v ∈ S} ≥ n/2 for every independent set S of G with |S| = k which has two distinct vertices x, y ∈ S satisfying 1 ≤ |N(x) ∩N(y)| ≤ α(G)− 1, th...