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- Yufa Shen, Wenjie He, Guoping Zheng, Yanpo Li
- Appl. Math. Lett.
- 2009

- Yufa Shen, Guoping Zheng, Wenjie He, Yongqiang Zhao
- Discrete Mathematics
- 2008

- Yufa Shen, Wenjie He, Guoping Zheng, Yanning Wang, Lingmin Zhang
- Discrete Mathematics
- 2008

A graph G is said to be chromatic-choosable if ch(G)= (G). Ohba has conjectured that every graph G with 2 (G)+ 1 or fewer vertices is chromatic-choosable. It is clear that Ohba’s conjecture is true if and only if it is true for complete multipartite graphs. But for complete multipartite graphs, the graphs for which Ohba’s conjecture has been verified are… (More)

- Wenjie He, Wenjing Miao, Yufa Shen
- Discrete Mathematics
- 2008

- Wenjie He, Lingmin Zhang, Daniel W. Cranston, Yufa Shen, Guoping Zheng
- Discrete Mathematics
- 2008

A graph G is called chromatic-choosable if its choice number is equal to its chromatic number, namely Ch(G) = χ(G). Ohba has conjectured that every graph G satisfying |V (G)| ≤ 2χ(G)+1 is chromatic-choosable. Since each k-chromatic graph is a subgraph of a complete k-partite graph, we see that Ohba's conjecture is true if and only if it is true for every… (More)

- Wenjie He, Xinkai Yu, Honghai Mi, Yong Xu, Yufa Shen, Lixin Wang
- Discrete Mathematics
- 2002

- Yufa Shen, Wenjie He, Xue Li, Donghong He, Xiaojing Yang
- Discrete Applied Mathematics
- 2008

A new proof concerning the determinant of the adjacency matrix of the line graph of a tree is presented and an invariant for line graphs, introduced by Cvetkovi´c and Lepovi´c, with least eigenvalue at least −2 is revisited and given a new equivalent definition [D. Cvetkovi´c and M. Lepovi´c. Cospectral graphs with least eigenvalue at least −2. Employing… (More)

- Wenjie He, Yufa Shen, Lixin Wang, Yanxun Chang, Qingde Kang, Xinkai Yu
- Discrete Mathematics
- 2001

Note The integral sum number of complete bipartite graphs K r; s Abstract A graph G =(V; E) is said to be an integral sum graph (sum graph) if its vertices can be given a labeling with distinct integers (positive integers), so that uv ∈ E if and only if u + v ∈ V. The integral sum number (sum number) of a given graph G, denoted by (G) ((G)), was deÿned as… (More)

- Zuo-Li Chen, Jin-Feng Lv, Yufa Shen, Guoping Zheng
- Discussiones Mathematicae Graph Theory
- 2010