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Let $G$ be a $t$-tough graph on $nge 3$ vertices for some $t>0$. It was shown by Bauer et al. in 1995 that if the minimum degree of $G$ is greater than $frac{n}{t+1}-1$, then $G$ is hamiltonian. In terms of Ores conditions in this direction, the problem was only studied when $t$ is between 1 and 2. In this paper, we show that if the degree sum of any two nonadjacent vertices of $G$ is greater than $frac{2n}{t+1}+t-2$, then $G$ is hamiltonian.
Chv{a}tal conjectured in 1973 the existence of some constant $t$ such that all $t$-tough graphs with at least three vertices are hamiltonian. While the conjecture has been proven for some special classes of graphs, it remains open in general. We say
We show that for any fixed $alpha>0$, cherry-quasirandom 3-graphs of positive density and sufficiently large order $n$ with minimum vertex degree $alpha binom n2$ have a tight Hamilton cycle. This solves a conjecture of Aigner-Horev and Levy.
Following a problem posed by Lovasz in 1969, it is believed that every connected vertex-transitive graph has a Hamilton path. This is shown here to be true for cubic Cayley graphs arising from groups having a $(2,s,3)$-presentation, that is, for grou
The toughness of a noncomplete graph $G$ is the maximum real number $t$ such that the ratio of $|S|$ to the number of components of $G-S$ is at least $t$ for every cutset $S$ of $G$, and the toughness of a complete graph is defined to be $infty$. Det
We give a sharp spectral condition for the existence of odd cycles in a graph of given order. We also prove a related stability result.