1 citations · 1 across the 4 of their papers we have counts for
7 papers
On a problem of Erdős about graphs whose size is the Turán number plus one
Pu Qiao, Xingzhi Zhan
We consider finite simple graphs. Given a graph and a positive integer the Turán number of for the order denoted is the maximum size of a graph o…
Relation between the number of leaves of a tree and its diameter
Pu Qiao, Xingzhi Zhan
Let denote the minimum possible number of leaves in a tree of order and diameter In 1975 Lesniak gave the lower bound for …
Pairs of a tree and a nontree graph with the same status sequence
Pu Qiao, Xingzhi Zhan
The status of a vertex in a graph is the sum of the distances between and all other vertices. Let be a connected graph. The status sequence of is the list of the st…
The largest graphs with given order and diameter: A simple proof
Pu Qiao, Xingzhi Zhan
A consequence of Ore's classic theorem characterizing the maximal graphs with given order and diameter is a determination of the largest such graphs. We give a very short and simpl…
Detour-saturated graphs of small girths
Pu Qiao, Xingzhi Zhan
A detour of a graph G is a longest path in G. The detour order of G is the number of vertices in a detour of G. A graph is said to be detour-saturated if the addition of any edge i…
The minimum number of Hamilton cycles in a hamiltonian threshold graph of a prescribed order
Pu Qiao, Xingzhi Zhan
We prove that the minimum number of Hamilton cycles in a hamiltonian threshold graph of order is and this minimum number is attained uniquely by th…