Journal of Combinatorial Theory Series B ( IF 1.4 ) Pub Date : 2021-12-17 , DOI: 10.1016/j.jctb.2021.12.002 Raphael Yuster 1
Let denote the maximum number of Hamiltonian cycles in an n-vertex r-graph with density . The expected number of Hamiltonian cycles in the random r-graph model is and in the random graph model with it is, in fact, slightly smaller than .
For graphs, is proved to be only larger than by a polynomial factor and it is an open problem whether a quasi-random graph with density p can be larger than by a polynomial factor.
For hypergraphs (i.e. ) the situation is drastically different. For all it is proved that is larger than by an exponential factor and, moreover, there are quasi-random r-graphs with density p whose number of Hamiltonian cycles is larger than by an exponential factor.
中文翻译:
r-graphs 和 quasi-random r-graphs 中超出预期的哈密顿循环
让 表示具有密度的n顶点r图中的哈密顿循环的最大数量. 随机r- graph 模型中哈密顿循环的预期数量 是 并在随机图模型中 和 事实上,它比 .
对于图形, 被证明只大于 通过多项式因子,密度为p的拟随机图是否可以大于 由多项式因子。
对于超图(即 )情况大不相同。对所有人 事实证明 大于 通过指数因子,此外,存在密度为p的准随机r图,其哈密顿循环的数量大于 由指数因子。