Displaying 541 – 560 of 669

Showing per page

Subsemi-Eulerian graphs.

Suffel, Charles, Tindell, Ralph, Hoffman, Cynthia, Mandell, Manachem (1982)

International Journal of Mathematics and Mathematical Sciences

Sufficient conditions on the existence of factors in graphs involving minimum degree

Huicai Jia, Jing Lou (2024)

Czechoslovak Mathematical Journal

For a set { A , B , C , ... } of graphs, an { A , B , C , ... } -factor of a graph G is a spanning subgraph F of G , where each component of F is contained in { A , B , C , ... } . It is very interesting to investigate the existence of factors in a graph with given minimum degree from the prospective of eigenvalues. We first propose a tight sufficient condition in terms of the Q -spectral radius for a graph involving minimum degree to contain a star factor. Moreover, we also present tight sufficient conditions based on the Q -spectral radius and the distance...

Sum of squares of degrees in a graph.

Ábrego, Bernardo M., Fernández-Merchant, Silvia, Neubauer, Michael G., Watkins, William (2009)

JIPAM. Journal of Inequalities in Pure & Applied Mathematics [electronic only]

Sur certaines équations fonctionnelles arithmétiques

Régis de La Bretèche, Gérald Tenenbaum (2000)

Annales de l'institut Fourier

Soit p k le k -ième nombre premier. Une fonction arithmétique complètement additive est définie sur * par la donnée des f ( p k ) et la formule f ( n ) = k 1 f ( p k ) v p k ( n ) ( n 1 ) , où v p désigne la...

The basis number of some special non-planar graphs

Salar Y. Alsardary, Ali A. Ali (2003)

Czechoslovak Mathematical Journal

The basis number of a graph G was defined by Schmeichel to be the least integer h such that G has an h -fold basis for its cycle space. He proved that for m , n 5 , the basis number b ( K m , n ) of the complete bipartite graph K m , n is equal to 4 except for K 6 , 10 , K 5 , n and K 6 , n with n = 5 , 6 , 7 , 8 . We determine the basis number of some particular non-planar graphs such as K 5 , n and K 6 , n , n = 5 , 6 , 7 , 8 , and r -cages for r = 5 , 6 , 7 , 8 , and the Robertson graph.

The cobondage number of a graph

V.R. Kulli, B. Janakiram (1996)

Discussiones Mathematicae Graph Theory

A set D of vertices in a graph G = (V,E) is a dominating set of G if every vertex in V-D is adjacent to some vertex in D. The domination number γ(G) of G is the minimum cardinality of a dominating set. We define the cobondage number b c ( G ) of G to be the minimum cardinality among the sets of edges X ⊆ P₂(V) - E, where P₂(V) = X ⊆ V:|X| = 2 such that γ(G+X) < γ(G). In this paper, the exact values of bc(G) for some standard graphs are found and some bounds are obtained. Also, a Nordhaus-Gaddum type...

The cost chromatic number and hypergraph parameters

Gábor Bacsó, Zsolt Tuza (2006)

Discussiones Mathematicae Graph Theory

In a graph, by definition, the weight of a (proper) coloring with positive integers is the sum of the colors. The chromatic sum is the minimum weight, taken over all the proper colorings. The minimum number of colors in a coloring of minimum weight is the cost chromatic number or strength of the graph. We derive general upper bounds for the strength, in terms of a new parameter of representations by edge intersections of hypergraphs.

Currently displaying 541 – 560 of 669