Let H be a hypergraph with vertex set V(H)and hyperedge set E(H).We call a vertex set R ■V(H)a transversal if it has a nonempty intersection with every hyperedge of H.The transversal number,denoted by τ(H),is the mi...Let H be a hypergraph with vertex set V(H)and hyperedge set E(H).We call a vertex set R ■V(H)a transversal if it has a nonempty intersection with every hyperedge of H.The transversal number,denoted by τ(H),is the minimum cardinality of transversals.In 2021,Diao verified that the upper bound of transversal number for any connected 3-uniform hypergraph H is at most 2m+1/3,that is,τ(H)≤2m+1/3, where m is the size of H.Moreover,they gave the necessary and sufficient conditions to reachthe upper bound,namely τ(H)≤2m+1/3,if and only if H is a hypertreewitha 3 perfect matching.In this paper,we investigate the transversal number of connected kunifom hypergraphs for k≥3.We confrm that τ(H)≤(k-1)m+1/k for any k-unifom hypegraphH with size m.Furthermore,we show that τ(H)≤(k-1)m+1/k if and only if H is a hypertree with a perfect matching,which generalizes the results of Diao.展开更多
In [1] the concepts of paths and cycles of a hypergraph were introduced. In this paper, we give the concepts for bipartite hypergraph and Hamiltonian paths and cycles of a hypergraph, and prove that the complete bipar...In [1] the concepts of paths and cycles of a hypergraph were introduced. In this paper, we give the concepts for bipartite hypergraph and Hamiltonian paths and cycles of a hypergraph, and prove that the complete bipartite 3-hypergraph with q vertices in earh part is Hamiltonian decomposable where q is a prime.展开更多
基金supported by the National Natural Science Foundation of China(No.12171089).
文摘Let H be a hypergraph with vertex set V(H)and hyperedge set E(H).We call a vertex set R ■V(H)a transversal if it has a nonempty intersection with every hyperedge of H.The transversal number,denoted by τ(H),is the minimum cardinality of transversals.In 2021,Diao verified that the upper bound of transversal number for any connected 3-uniform hypergraph H is at most 2m+1/3,that is,τ(H)≤2m+1/3, where m is the size of H.Moreover,they gave the necessary and sufficient conditions to reachthe upper bound,namely τ(H)≤2m+1/3,if and only if H is a hypertreewitha 3 perfect matching.In this paper,we investigate the transversal number of connected kunifom hypergraphs for k≥3.We confrm that τ(H)≤(k-1)m+1/k for any k-unifom hypegraphH with size m.Furthermore,we show that τ(H)≤(k-1)m+1/k if and only if H is a hypertree with a perfect matching,which generalizes the results of Diao.
基金the National Natural Science Foundation of China (No.19831080).
文摘In [1] the concepts of paths and cycles of a hypergraph were introduced. In this paper, we give the concepts for bipartite hypergraph and Hamiltonian paths and cycles of a hypergraph, and prove that the complete bipartite 3-hypergraph with q vertices in earh part is Hamiltonian decomposable where q is a prime.
