In this paper,we consider Seymour’s Second Neighborhood Conjecture in3-free digraphs,and prove that for any 3-free digraph D,there exists a vertex say v,such that d^++(v)≥[λd+(v)],λ=0.6958….This slightly improves...In this paper,we consider Seymour’s Second Neighborhood Conjecture in3-free digraphs,and prove that for any 3-free digraph D,there exists a vertex say v,such that d^++(v)≥[λd+(v)],λ=0.6958….This slightly improves the known results in 3-free digraphs with large minimum out-degree.展开更多
文摘In this paper,we consider Seymour’s Second Neighborhood Conjecture in3-free digraphs,and prove that for any 3-free digraph D,there exists a vertex say v,such that d^++(v)≥[λd+(v)],λ=0.6958….This slightly improves the known results in 3-free digraphs with large minimum out-degree.
基金partially supported by the Fundamental Research Funds for the Central Universities,Nankai Universitypartially supported by NSFC(Nos.12161141006,12111540249)+2 种基金the Natural Science Foundation of Tianjin(No.20JCJQJC00090)the Fundamental Research Funds for the Central Universities,Nankai Universitypartially supported by grant DFF-7014-00037B of Independent Research Fund Denmark。
