1Department of Mathematics, St. Xavier’s College (Autonomous), Palayamkottai-627002, India.
2Center: PG and Research Department of Mathematics, St. Xavier’s College (Autonomous), Palayamkottai-627002, Manonmaniam Sundaranar University, Abisekapatti-627012, Tamilnadu, India.
Consider a total labeling of a graph . For every two different edges and of , let where weight of is defined as . Then is called edge irregular total absolute difference -labeling of . Let be the minimum integer for which there is a graph with edge irregular total absolute difference labeling. This is called the total absolute difference edge irregularity strength of the graph , denoted . We compute of , disjoint union of grid and zigzag graph.
Chartrand et al. [1]
introduced irregularity strength and irregular assignments of a graph in
1988. The other kind of total labeling the total edge irregularity
strength of a graph was studied by Baca et al. [2]: Consider a graph . A labeling is called an edge irregular total -labeling if for every pair of distinct
edges and , . If a graph admits an edge irregular total -labeling and is minimum then is said to have a total edge
irrgularity strength denoted by . The results about the can be found in [3,4,5,6,7,8,9,10].
Ramalakshmi and Kathiresan introduced the total absolute difference
edge irregularity strength of graphs to lower edge weights, using and graceful labeling. Consider a
total labeling of a graph . For every two different edges and of , let where weight of is defined as . Then
is called edge irregular total absolute difference -labeling of . Let be the minimum integer for which there
is a graph with edge irregular
total absolute difference labeling. This is called the total absolute difference
edge irregularity strength of the graph , denoted .
Lourdusamy et al. [11]
determined the total absolute difference edge irregular strength for
snake related graphs, wheel related graphs, lotus inside the circle and
double fan graph. Also, they obtained the of -tree related graphs [12]. Lourdusamy et al. [13] discussed the of super subdivision of certain
families of graphs and corona graphs. Also, they obtained the of transformed tree and path
related graphs [14]. Here, we
discuss the of staircase
graph, disjoint union of zigzag and grid graphs.
In this section, we compute the exact value of total absolute
difference edge irregularity strength of staircase graph.
Theorem 2. For , the total absolute difference
edge irregularity strength is .
Proof. Let . Let and
.
Note that and .
Figure 1.
From Theorem 1, . To complete the proof we show that . We define a, -labeling as follows:
For Case 1. is odd
Let and is odd .
Fix
Let and is odd.
Fix Case 2. is even
Let and is even.
Fix
Let and is even.
Fix
We fix the edge labels as follows: ; ; ; , for ; , for and ; , for and ; , for and .
We then have the weight of the edges as follows: ; ; ; for
; ,
for and ; ,
for and ; ,
for and .
Hence is total absolute
difference edge irregular -labeling with as the weights for the edges are different.
3. Disjoint Union of Zigzag
Graph
In this section, we compute the exact value of total absolute
difference edge irregularity strength of disjoint union of zigzag graphs
with and .
Theorem 3. For any integer , , .
Proof. Let . The disjoint
union of zigzag graphs is defined to be a graph with
vertex set and the edge set . The disjoint union of zigzag graphs
has
vertices and edges.
Based on Theorem 1, we have .
Figure 2.
We define as follows:
for , and , where ;
for , and , ; , for , and ; , for , ; , for ; ,
for , and
We now arrive at the weight of the edges:
for , , and ,
for , , and ,
It is clear that, the labels for vertices and edges receive values are
not more than . Also we see that
the weights for the edges are all distinct. Hence .
Illustration for of is shown in Figure 3.
Figure 3.
4. Disjoint Union of Grid Graph
In this section, we compute the exact value of total absolute
difference edge irregularity strength of disjoint union of grid graphs
with .
Theorem 4. For any integer and , .
Proof. Let . We define disjoint union of grid
graphs as follows:
Let . Let . From Theorem 1, . Now we prove the converse part.
Figure 4.
Let us define as follows:
for , and ,
where
for and
for , ; , for , and ; , for , ; , for ; ,
for , and
Below we arrive at the weight of the edges. for , , and ,
for , , and ,
It is clear that, the labels for vertices and edges receive values are
not more than . Also we see that
the weights for the edges are all distinct. Hence
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