VERTEX COVERING TRANSVERSAL DOMATIC NUMBER OF GRAPHS

2017 ◽  
Vol 18 (1) ◽  
pp. 87-105
Author(s):  
R. Vasanthi ◽  
K. Subramanian
Keyword(s):  
Domatic Number ◽  
Vertex Covering

scholarly journals The geodetic vertex covering number of a graph

2020 ◽  
Vol 8 (2) ◽  
pp. 683-689
Author(s):  
V.M. Arul Flower Mary ◽  
J. Anne Mary Leema ◽  
P. Titus ◽  
B. Uma Devi
Keyword(s):  
Covering Number ◽  
Vertex Covering

scholarly journals On k-rainbow domination in middle graphs

2021 ◽  
Author(s):  
Kijung Kim
Keyword(s):  
Minimum Weight ◽  
Domination Number ◽  
Simple Graph ◽  
Upper And Lower Bounds ◽  
Matching Number ◽  
Domatic Number ◽  
Rainbow Domination ◽  
Vertex Set ◽  
Middle Graph ◽  
Dominating Function

Let $G$ be a finite simple graph with vertex set $V(G)$ and edge set $E(G)$. A function $f : V(G) \rightarrow \mathcal{P}(\{1, 2, \dotsc, k\})$ is a \textit{$k$-rainbow dominating function} on $G$ if for each vertex $v \in V(G)$ for which $f(v)= \emptyset$, it holds that $\bigcup_{u \in N(v)}f(u) = \{1, 2, \dotsc, k\}$. The weight of a $k$-rainbow dominating function is the value $\sum_{v \in V(G)}|f(v)|$. The \textit{$k$-rainbow domination number} $\gamma_{rk}(G)$ is the minimum weight of a $k$-rainbow dominating function on $G$. In this paper, we initiate the study of $k$-rainbow domination numbers in middle graphs. We define the concept of a middle $k$-rainbow dominating function, obtain some bounds related to it and determine the middle $3$-rainbow domination number of some classes of graphs. We also provide upper and lower bounds for the middle $3$-rainbow domination number of trees in terms of the matching number. In addition, we determine the $3$-rainbow domatic number for the middle graph of paths and cycles.

scholarly journals On the König deficiency of zero-reducible graphs

2019 ◽  
Vol 39 (1) ◽  
pp. 273-292
Author(s):  
Miklós Bartha ◽  
Miklós Krész
Keyword(s):  
Perfect Matching ◽  
Linear Time ◽  
Perfect Matchings ◽  
Covering Number ◽  
Matching Number ◽  
Empty Graph ◽  
Reduction System ◽  
Vertex Covering ◽  
Np Complete ◽  
The Difference

Abstract A confluent and terminating reduction system is introduced for graphs, which preserves the number of their perfect matchings. A union-find algorithm is presented to carry out reduction in almost linear time. The König property is investigated in the context of reduction by introducing the König deficiency of a graph G as the difference between the vertex covering number and the matching number of G. It is shown that the problem of finding the König deficiency of a graph is NP-complete even if we know that the graph reduces to the empty graph. Finally, the König deficiency of graphs G having a vertex v such that $$G-v$$G-v has a unique perfect matching is studied in connection with reduction.

On the Roman {2}-domatic number of graphs

2020 ◽  
pp. 2150052
Author(s):  
A. Giahtazeh ◽  
H. R. Maimani ◽  
A. Iranmanesh
Keyword(s):  
Bipartite Graphs ◽  
Domatic Number ◽  
Join Of Graphs ◽  
Complete Bipartite Graphs ◽  
Appl Math ◽  
Dominating Function

Let [Formula: see text] be a graph. A Roman[Formula: see text]-dominating function [Formula: see text] has the property that for every vertex [Formula: see text] with [Formula: see text], either [Formula: see text] is adjacent to a vertex assigned [Formula: see text] under [Formula: see text], or [Formula: see text] is adjacent to at least two vertices assigned [Formula: see text] under [Formula: see text]. A set [Formula: see text] of distinct Roman [Formula: see text]-dominating functions on [Formula: see text] with the property that [Formula: see text] for each [Formula: see text] is called a Roman[Formula: see text]-domination family (or functions) on [Formula: see text]. The maximum number of functions in a Roman [Formula: see text]-dominating family on [Formula: see text] is the Roman[Formula: see text]-domatic number of [Formula: see text], denoted by [Formula: see text]. In this paper, we answer two conjectures of Volkman [L. Volkmann, The Roman [Formula: see text]-domatic number of graphs, Discrete Appl. Math. 258 (2019) 235–241] about Roman [Formula: see text]-domatic number of graphs and we study this parameter for join of graphs and complete bipartite graphs.

scholarly journals ENTOMOLOGICAL NOTES: DESCRIPTIONS OF FOUR NEW SPECIES OF CANADIAN HYMENOPTERA

1869 ◽  
Vol 1 (12) ◽  
pp. 103-105 ◽  
Author(s):  
E. T. Cresson
Keyword(s):  
New Species ◽  
Anterior Margin ◽  
Lateral Margin ◽  
Black Spots ◽  
Vertex Covering ◽  
Fourth Segment

Euceros Canadensis, n. sp.—Female. Shining : head yellow ; two spots behind antennæ, confluent with a mark on vertex, covering ocelli and occiput, and tips of mandibles, black; antennæ black, palish at base beneath; thorax black, lateral margin of mesothorax in front of tegulæ, two lines on disk, a spot on each side before scutellum, a broad V-shaped mark on scutellum, apex of metathorax, which has two black spots above, anterior margin of prothorax, a spot on each side of pleura, and the tegulæ, yellow; wings hyaline, dusky on apical malgin; legs yellow, anterior coxæ in front, posterioi coxæ,their femora, except base and apex,and their tibiæ, except base, black, their tarsi, except tips, fuscous; abdomen yellow; a triangular mark on each side of first segment, a transverse mark on each side of second and third segments, dilated laterally, and the remaining segments, except medial spot at tip of fourth segment, and another on extreme tip of abdomen, blackish; venter entirely yel1ow.—Length, 5¼ lines.

On the minimum vertex covering transversal dominating sets in graphs and their classification

2017 ◽  
Vol 09 (05) ◽  
pp. 1750069 ◽  
Author(s):  
R. Vasanthi ◽  
K. Subramanian
Keyword(s):  
Connected Graph ◽  
Dominating Set ◽  
Domination Number ◽  
Dominating Sets ◽  
Minimum Cardinality ◽  
Vertex Covering ◽  
Number Formula ◽  
Covering Set ◽  
Simple Connected Graph

Let [Formula: see text] be a simple and connected graph. A dominating set [Formula: see text] is said to be a vertex covering transversal dominating set if it intersects every minimum vertex covering set of [Formula: see text]. The vertex covering transversal domination number [Formula: see text] is the minimum cardinality among all vertex covering transversal dominating sets of [Formula: see text]. A vertex covering transversal dominating set of minimum cardinality [Formula: see text] is called a minimum vertex covering transversal dominating set or simply a [Formula: see text]-set. In this paper, we prove some general theorems on the vertex covering transversal domination number of a simple connected graph. We also provide some results about [Formula: see text]-sets and try to classify those sets based on their intersection with the minimum vertex covering sets.

Sign in / Sign up

Export Citation Format

Share Document