Autor: Shan, Erfang - Katalog OPAC zbiorów

Skocz do pozycji: 1.

Tytuł:: Trees with Unique Least Central Subtrees
Autorzy:: Kang, Liying
Shan, Erfang
Powiązania:: https://bibliotekanauki.pl/articles/31342276.pdf
Data publikacji:: 2018-08-01
Wydawca:: Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:: tree
central subtree
least central subtree
Opis:: A subtree S of a tree T is a central subtree of T if S has the minimum eccentricity in the join-semilattice of all subtrees of T. Among all subtrees lying in the join-semilattice center, the subtree with minimal size is called the least central subtree. Hamina and Peltola asked what is the characterization of trees with unique least central subtree? In general, it is difficult to characterize completely the trees with unique least central subtree. Nieminen and Peltola [The subtree center of a tree, Networks 34 (1999) 272–278] characterized the trees with the least central subtree consisting just of a single vertex. This paper characterizes the trees having two adjacent vertices as a unique least central subtree.
Źródło:: Discussiones Mathematicae Graph Theory; 2018, 38, 3; 811-828
2083-5892
Pojawia się w:: Discussiones Mathematicae Graph Theory
Dostawca treści:: Biblioteka Nauki

Artykuł

Skocz do pozycji: 2.

Tytuł:: On the Numbers of Cut-Vertices and End-Blocks in 4-Regular Graphs
Autorzy:: Wang, Dingguo
Shan, Erfang
Powiązania:: https://bibliotekanauki.pl/articles/30148001.pdf
Data publikacji:: 2014-02-01
Wydawca:: Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:: 4-regular graph
claw-free
cut-vertices
end-blocks
Opis:: A cut-vertex in a graph G is a vertex whose removal increases the number of connected components of G. An end-block of G is a block with a single cut-vertex. In this paper we establish upper bounds on the numbers of end-blocks and cut-vertices in a 4-regular graph G and claw-free 4-regular graphs. We characterize the extremal graphs achieving these bounds.
Źródło:: Discussiones Mathematicae Graph Theory; 2014, 34, 1; 127-136
2083-5892
Pojawia się w:: Discussiones Mathematicae Graph Theory
Dostawca treści:: Biblioteka Nauki

Artykuł

Skocz do pozycji: 3.

Tytuł:: On characterization of uniquely 3-list colorable complete multipartite graphs
Autorzy:: Zhao, Yancai
Shan, Erfang
Powiązania:: https://bibliotekanauki.pl/articles/744543.pdf
Data publikacji:: 2010
Wydawca:: Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:: list coloring
complete multipartite graph
uniquely 3-list colorable graph
Opis:: For each vertex v of a graph G, if there exists a list of k colors, L(v), such that there is a unique proper coloring for G from this collection of lists, then G is called a uniquely k-list colorable graph. Ghebleh and Mahmoodian characterized uniquely 3-list colorable complete multipartite graphs except for nine graphs: $K_{2,2,r}$ r ∈ {4,5,6,7,8}, $K_{2,3,4}$, $K_{1*4,4}$, $K_{1*4,5}$, $K_{1*5,4}$. Also, they conjectured that the nine graphs are not U3LC graphs. After that, except for $K_{2,2,r}$ r ∈ {4,5,6,7,8}, the others have been proved not to be U3LC graphs. In this paper we first prove that $K_{2,2,8}$ is not U3LC graph, and thus as a direct corollary, $K_{2,2,r}$ (r = 4,5,6,7,8) are not U3LC graphs, and then the uniquely 3-list colorable complete multipartite graphs are characterized completely.
Źródło:: Discussiones Mathematicae Graph Theory; 2010, 30, 1; 105-114
2083-5892
Pojawia się w:: Discussiones Mathematicae Graph Theory
Dostawca treści:: Biblioteka Nauki

Artykuł

Skocz do pozycji: 4.

Tytuł:: Asymptotic Sharpness of Bounds on Hypertrees
Autorzy:: Lin, Yi
Kang, Liying
Shan, Erfang
Powiązania:: https://bibliotekanauki.pl/articles/31341637.pdf
Data publikacji:: 2017-08-01
Wydawca:: Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:: hypertree
semicycle in hypergraph
chain in hypergraph
Opis:: The hypertree can be defined in many different ways. Katona and Szabó introduced a new, natural definition of hypertrees in uniform hypergraphs and investigated bounds on the number of edges of the hypertrees. They showed that a $k$-uniform hypertree on $n$ vertices has at most $ \binom{n}{k−1} $ edges and they conjectured that the upper bound is asymptotically sharp. Recently, Szabó verified that the conjecture holds by recursively constructing an infinite sequence of $k$-uniform hypertrees and making complicated analyses for it. In this note we give a short proof of the conjecture by directly constructing a sequence of $k$-uniform $k$-hypertrees.
Źródło:: Discussiones Mathematicae Graph Theory; 2017, 37, 3; 789-795
2083-5892
Pojawia się w:: Discussiones Mathematicae Graph Theory
Dostawca treści:: Biblioteka Nauki

Artykuł

Skocz do pozycji: 5.

Tytuł:: Power Domination in the Generalized Petersen Graphs
Autorzy:: Zhao, Min
Shan, Erfang
Kang, Liying
Powiązania:: https://bibliotekanauki.pl/articles/31348324.pdf
Data publikacji:: 2020-08-01
Wydawca:: Uniwersytet Zielonogórski. Wydział Matematyki, Informatyki i Ekonometrii
Tematy:: power domination
domination
generalized Petersen graph
electric power system
Opis:: The problem of monitoring an electric power system by placing as few measurement devices in the system can be formulated as a power dominating set problem in graph theory. The power domination number of a graph is the minimum cardinality of a power dominating set. Xu and Kang [On the power domination number of the generalized Petersen graphs, J. Comb. Optim. 22 (2011) 282–291] study the exact power domination number for the generalized Petersen graph P (3k, k), and propose the following problem: determine the power domination number for the generalized Petersen graph P (4k, k) or P (ck, k). In this paper we give the power domination number for P (4k, k) and present a sharp upper bound on the power domination number for the generalized Petersen graph P (ck, k).
Źródło:: Discussiones Mathematicae Graph Theory; 2020, 40, 3; 695-712
2083-5892
Pojawia się w:: Discussiones Mathematicae Graph Theory
Dostawca treści:: Biblioteka Nauki

Artykuł

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