172 research outputs found
BILANGAN KROMATIK HARMONIS PADA GRAF PAYUNG, GRAF PARASUT, DAN GRAF SEMI PARASUT
This article discusses the harmonic coloring of simple graphs G, namely umbrella graphs, parachute graphs, and semi-parachute graphs. A vertex coloring on a graph G is a harmonic coloring if each pair of colors (based on edges or pair of vertices) appears at most once. The chromatic number associated with the harmonic coloring of graph G is called the harmonic chromatic number denoted XH(G). In this article, the exact values of harmonic chromatic numbers are obtained for umbrella graphs, parachute graphs, and semi-parachute graphs
The Edge-Distinguishing Chromatic Number of Petal Graphs, Chorded Cycles, and Spider Graphs
The edge-distinguishing chromatic number (EDCN) of a graph is the minimum
positive integer such that there exists a vertex coloring
whose induced edge labels are
distinct for all edges . Previous work has determined the EDCN of paths,
cycles, and spider graphs with three legs. In this paper, we determine the EDCN
of petal graphs with two petals and a loop, cycles with one chord, and spider
graphs with four legs. These are achieved by graph embedding into looped
complete graphs.Comment: 23 pages, 1 figur
Upward Three-Dimensional Grid Drawings of Graphs
A \emph{three-dimensional grid drawing} of a graph is a placement of the
vertices at distinct points with integer coordinates, such that the straight
line segments representing the edges do not cross. Our aim is to produce
three-dimensional grid drawings with small bounding box volume. We prove that
every -vertex graph with bounded degeneracy has a three-dimensional grid
drawing with volume. This is the broadest class of graphs admiting
such drawings. A three-dimensional grid drawing of a directed graph is
\emph{upward} if every arc points up in the z-direction. We prove that every
directed acyclic graph has an upward three-dimensional grid drawing with
volume, which is tight for the complete dag. The previous best upper
bound was . Our main result is that every -colourable directed
acyclic graph ( constant) has an upward three-dimensional grid drawing with
volume. This result matches the bound in the undirected case, and
improves the best known bound from for many classes of directed
acyclic graphs, including planar, series parallel, and outerplanar
On the Graceful Game
A graceful labeling of a graph with edges consists of labeling the
vertices of with distinct integers from to such that, when each
edge is assigned as induced label the absolute difference of the labels of its
endpoints, all induced edge labels are distinct. Rosa established two well
known conjectures: all trees are graceful (1966) and all triangular cacti are
graceful (1988). In order to contribute to both conjectures we study graceful
labelings in the context of graph games. The Graceful game was introduced by
Tuza in 2017 as a two-players game on a connected graph in which the players
Alice and Bob take turns labeling the vertices with distinct integers from 0 to
. Alice's goal is to gracefully label the graph as Bob's goal is to prevent
it from happening. In this work, we study winning strategies for Alice and Bob
in complete graphs, paths, cycles, complete bipartite graphs, caterpillars,
prisms, wheels, helms, webs, gear graphs, hypercubes and some powers of paths
Friendly index sets of starlike graphs
For a graph G = (V, E) and a coloring (labeling) f : V(G) → Z2 let vf(i) = | f-1(i)|. The coloring f is said to be friendly if |vf(1) - v f(0)| ≤ 1. The coloring f : V( G) → Z2 induces an edge labeling f* : E( G) → Z2 defined by f* (xy) = f( x) + f(y) (mod 2). Let ef(i) = |f*-1( i)|. The friendly index set of the graph G, denoted by FI (G), is defined by FIG= ef1-ef 0:f isafriendly vertexlabelingof G. In this thesis the friendly index sets of certain classes of trees, called starlike graphs, will be determined
The b-Chromatic Number of Star Graph Families
In this paper, we investigate the b-chromatic number of central graph, middle graph and total graph of star graph, denoted by C(K1,n), M(K1,n) and T(K1,n) respectively. We discuss the relationship between b-chromatic number with some other types of chromatic numbers such as chromatic number, star chromatic number and equitable chromatic number
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