Displaying 221 – 240 of 428

Showing per page

On connectedness of graphs on direct product of Weyl groups

Samy A. Youssef, S. G. Hulsurkar (1995)

Archivum Mathematicum

In this paper, we have studied the connectedness of the graphs on the direct product of the Weyl groups. We have shown that the number of the connected components of the graph on the direct product of the Weyl groups is equal to the product of the numbers of the connected components of the graphs on the factors of the direct product. In particular, we show that the graph on the direct product of the Weyl groups is connected iff the graph on each factor of the direct product is connected.

On distinguishing and distinguishing chromatic numbers of hypercubes

Werner Klöckl (2008)

Discussiones Mathematicae Graph Theory

The distinguishing number D(G) of a graph G is the least integer d such that G has a labeling with d colors that is not preserved by any nontrivial automorphism. The restriction to proper labelings leads to the definition of the distinguishing chromatic number χ D ( G ) of G. Extending these concepts to infinite graphs we prove that D ( Q ) = 2 and χ D ( Q ) = 3 , where Q denotes the hypercube of countable dimension. We also show that χ D ( Q ) = 4 , thereby completing the investigation of finite hypercubes with respect to χ D . Our results...

On iteration digraph and zero-divisor graph of the ring n

Tengxia Ju, Meiyun Wu (2014)

Czechoslovak Mathematical Journal

In the first part, we assign to each positive integer n a digraph Γ ( n , 5 ) , whose set of vertices consists of elements of the ring n = { 0 , 1 , , n - 1 } with the addition and the multiplication operations modulo n , and for which there is a directed edge from a to b if and only if a 5 b ( mod n ) . Associated with Γ ( n , 5 ) are two disjoint subdigraphs: Γ 1 ( n , 5 ) and Γ 2 ( n , 5 ) whose union is Γ ( n , 5 ) . The vertices of Γ 1 ( n , 5 ) are coprime to n , and the vertices of Γ 2 ( n , 5 ) are not coprime to n . In this part, we study the structure of Γ ( n , 5 ) in detail. In the second part, we investigate the zero-divisor...

On L-ideal-based L-zero-divisor graphs

S. Ebrahimi Atani, M. Shajari Kohan (2011)

Discussiones Mathematicae - General Algebra and Applications

In a manner analogous to a commutative ring, the L-ideal-based L-zero-divisor graph of a commutative ring R can be defined as the undirected graph Γ(μ) for some L-ideal μ of R. The basic properties and possible structures of the graph Γ(μ) are studied.

On permutographs

Thomas, Gerhard G. (1982)

Proceedings of the 10th Winter School on Abstract Analysis

Currently displaying 221 – 240 of 428