Displaying 601 – 620 of 1336

Showing per page

On permutographs

Thomas, Gerhard G. (1982)

Proceedings of the 10th Winter School on Abstract Analysis

On potentially H -graphic sequences

Meng Xiao Yin, Jian Hua Yin (2007)

Czechoslovak Mathematical Journal

For given a graph H , a graphic sequence π = ( d 1 , d 2 , ... , d n ) is said to be potentially H -graphic if there is a realization of π containing H as a subgraph. In this paper, we characterize the potentially ( K 5 - e ) -positive graphic sequences and give two simple necessary and sufficient conditions for a positive graphic sequence π to be potentially K 5 -graphic, where K r is a complete graph on r vertices and K r - e is a graph obtained from K r by deleting one edge. Moreover, we also give a simple necessary and sufficient condition for...

On potentially K 5 - H -graphic sequences

Lili Hu, Chunhui Lai, Ping Wang (2009)

Czechoslovak Mathematical Journal

Let K m - H be the graph obtained from K m by removing the edges set E ( H ) of H where H is a subgraph of K m . In this paper, we characterize the potentially K 5 - P 4 and K 5 - Y 4 -graphic sequences where Y 4 is a tree on 5 vertices and 3 leaves.

On potentially nilpotent double star sign patterns

Honghai Li, Jiongsheng Li (2009)

Czechoslovak Mathematical Journal

A matrix 𝒜 whose entries come from the set { + , - , 0 } is called a sign pattern matrix, or sign pattern. A sign pattern is said to be potentially nilpotent if it has a nilpotent realization. In this paper, the characterization problem for some potentially nilpotent double star sign patterns is discussed. A class of double star sign patterns, denoted by 𝒟 S S P ( m , 2 ) , is introduced. We determine all potentially nilpotent sign patterns in 𝒟 S S P ( 3 , 2 ) and 𝒟 S S P ( 5 , 2 ) , and prove that one sign pattern in 𝒟 S S P ( 3 , 2 ) is potentially stable.

On prime labeling of union of tadpole graphs

Sanjaykumar K. Patel, Jayesh B. Vasava (2022)

Commentationes Mathematicae Universitatis Carolinae

A graph G of order n is said to be a prime graph if its vertices can be labeled with the first n positive integers in such a way that the labels of any two adjacent vertices in G are relatively prime. If such a labeling on G exists then it is called a prime labeling. In this paper we seek prime labeling for union of tadpole graphs. We derive a necessary condition for the existence of prime labelings of graphs that are union of tadpole graphs and further show that the condition is also sufficient...

Currently displaying 601 – 620 of 1336