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(1)

ON THE PARTITION DIMENSION OF A LOLLIPOP GRAPH, A

GENERALIZED JAHANGIR GRAPH, AND A

C

n

βˆ—

2

K

m

GRAPH

Maylinda Purna Kartika Dewi and Tri Atmojo Kusmayadi

Department of Mathematics

Faculty of Mathematics and Natural Sciences Sebelas Maret University

Abstract. Let G be a connected graph with vertex set V(G) = {v1, v2, . . . , vn} and edge setE(G) ={e1, e2, . . . , en}. The vertex set V(G) is divided into some partitions, which are S1, S2, . . . , Sk. For every vertex v ∈ V(G) and an ordered k-partition Ξ  = {S1, S2, . . . , Sk}, the representation ofvwith respect to Ξ  isr(v|Ξ ) = (d(v, S1), d(v, S2), . . . , d(v, Sk)), where d(v, Si) represents the distance of the vertexv to each partition in Ξ . The set Ξ  is said to be resolved partition ofGif the representationr(v|Ξ ) are distinct, for every vertex v in G. The minimum cardinality of resolving k-partition of V(G) is called the partition dimension of G, denoted by pd(G). In this research, we determine the partition dimension of a lollipop graphLm,n, a generalized Jahangir graphJm,n, and aCnβˆ—2Km graph.

Keywords :partition dimension, resolving partition, lollipop graph, generalized Jahangir

graph,Cnβˆ—2Km graph

1.

Introduction

The partition dimension of a graph was introduced by Chartrand et al. [2] in

1998. There is another concept of metric dimension form. We assume that

G

is a

graph with a vertex set

V

(

G

), such that

V

(

G

) can be divided into any partition

set

S

. The set Ξ  with

S

∈

Ξ  is a resolving partition of

G

if for each vertex in

G

has distinct representation with respect to Ξ , and Ξ  is an ordered

k

βˆ’

partition.

The minimum cardinality of resolving

k

βˆ’

partitions of

V

(

G

) is called a partition

dimension of

G

, denoted by

pd

(

G

).

Many researchers have conducted research in determining the partition dimension

for specific graph classes. Tomescu et al. [9] in 2007 found the partition dimension

of a wheel graph. Javaid and Shokat [6] in 2008 determined the partition dimension

of some wheel related graphs, such as a gear graph, a helm graph, a sunflower graph,

and a friendship graph. Asmiati [1] in 2012 investigated the partition dimension of a

star amalgamation. Hidayat [5] in 2015 determined the partition dimension of some

graph classes, they are a (

n, t

)

βˆ’

kite

graph, a barbell graph, a double cones graph,

and a

K

1

+ (

P

m

βŠ™

K

n

) graph. Danisa [4] in 2015 found the partition dimension of a

flower graph, a 3

βˆ’

fold wheel graph, and a (

K

m

Γ—

P

n

)

βŠ™

K

1

. Puspitaningrum [8] in

2015 also found the partition dimension of a closed helm graph, a

W

n

Γ—

P

m

graph,

(2)

and a

C

m

βŠ™

K

1,n

graph. In this research, we determine the partition dimension of a

lollipop graph, a generalized Jahangir graph, and a

C

n

βˆ—

2

K

m

graph.

2.

Partition Dimension

The following definition and lemma were given by Chartrand et al. [3]. Let

G

be a connected graph. For a subset

S

of

V

(

G

) and a vertex

v

of

G

, the distance

d

(

v, S

) between

v

and

S

is defined as

d

(

v, S

) =

min

{

d

(

v, x

)

|

x

∈

S

}

. For an ordered

k

-partition Ξ  =

{

S

1

, S

2

, . . . , S

k

}

of

V

(

G

) and a vertex

v

of

G

, the representation of

v

with respect to Ξ  is defined as the

k

-vector

r

(

v

|

Ξ ) = (

d

(

v, S

1

)

, d

(

v, S

2

)

, . . . , d

(

v, S

k

)).

The partition Ξ  is called a resolving partition if the

k

-vectors

r

(

v

|

Ξ )

, v

∈

V

(

G

) are

distinct. The minimum

k

for which there is a resolving

k

-partition of

V

(

G

) is called

the partition dimension of

G

, denoted by

pd

(

G

).

Lemma 2.1.

Let

G

be a connected graph, then

(1)

pd

(

G

) = 2

if and only if

G

=

P

n

for

n

β‰₯

2

,

(2)

pd

(

G

) =

n

if and only if

G

=

K

n

, and

(3)

pd

(

G

) = 3

if

G

=

n

-cycle

for

n

β‰₯

3

.

Lemma 2.2.

Let

Ξ 

be a resolving partition of

V

(

G

)

and

u, v

∈

V

(

G

)

. If

d

(

u, w

) =

d

(

v, w

)

for all

w

∈

V

(

G

)

βˆ’ {

u, v

}

, then

u

and

v

belong to distinct elements of

Ξ 

.

Proof.

Let Ξ  =

{

S

1

, S

2

, . . . , S

k

}

, where

u

and

v

belong to the same element, say

S

i

,

of Ξ . Then

d

(

u, S

i

) =

d

(

v, S

i

) = 0. Since

d

(

u, w

) =

d

(

v, w

) for all

w

∈

V

(

G

)

βˆ’{

u, v

}

,

we also have that

d

(

u, S

j

) =

d

(

v, S

j

) for all

j

, where 1

≀

j

ΜΈ

=

i

≀

k

. Therefore,

r

(

u

|

Ξ ) =

r

(

v

|

Ξ ) and Ξ  is not a resolving partition.

3.

The Partition Dimension of a Lollipop Graph

Weisstein [10] defined the lollipop graph

L

m,n

for

m

β‰₯

3 as a graph obtained by

joining a complete graph

K

m

to a path

P

n

with a bridge.

Theorem 3.1.

Let

L

m,n

be a lollipop graph with

m

β‰₯

3

and

n

β‰₯

1

, then

pd

(

L

m,n

) =

m.

Proof.

Let

V

(

L

m,n

) =

V

(

K

m

)

βˆͺ

V

(

P

n

), where

V

(

K

m

) =

{

v

1

, v

2

, . . . , v

mβˆ’1

, v

m

}

and

V

(

P

n

) =

{

u

1

, u

2

, . . . , u

nβˆ’1

, u

n

}

. Take a vertex

v

∈

V

(

K

m

) such that

v

is adjacent

to

u

∈

V

(

P

n

). Based on Lemma 2.1.1 and Lemma 2.1.2, the partition dimension

of

L

m,n

is

pd

(

L

m,n

)

β‰₯

m

. Next, we show that the partition dimension of

L

m,n

is

(3)

partition where

S

i

=

{

v

i

}

for 1

≀

i

≀

m

βˆ’

1 and

S

m

=

{

v

m

, u

1

, . . . , u

n

}

. We obtain

the representation between all vertices of

V

(

L

m,n

) with respect to Ξ  as follows

r

(

v

m

|

Ξ ) = (

d

(

v

1

, S

i

)

, . . . , d

(

v

m

, S

i

)) and

r

(

u

n

|

Ξ ) = (

n, n

+ 1

, n

+ 1

, . . . , n

+ 1

,

0)

where

d

(

v

m

, S

i

) =

{

0

,

for

S

i

∈

Ξ  with

i

=

m,

1

,

for

S

i

∈

Ξ  with

i

ΜΈ

=

m.

Therefore, for each vertex

v

∈

V

(

L

m,n

) has a distinct representation with respect

to Ξ . Now, we show that the cardinality of Ξ  is

m

. The cardinality of Ξ  is the

number of

k

βˆ’

partition in

S

i

and

S

m

for 1

≀

i

≀

m

βˆ’

1. The number of

k

βˆ’

partition

in

S

i

for 1

≀

i

≀

m

βˆ’

1, is

m

βˆ’

1. The number of

k

βˆ’

partition in

S

m

is 1, so we

have

|

Ξ 

|

= (

m

βˆ’

1) + 1 =

m

. Furthermore, Ξ  =

{

S

1

, S

2

, . . . , S

m

}

is a resolving

partition of

L

m,n

with

m

elements. Hence, the partition dimension of lollipop graph

is

pd

(

L

m,n

) =

m

.

4.

The Partition Dimension of a Generalized Jahangir Graph

Mojdeh and Ghameshlou [7] defined the generalized Jahangir graph

J

m,n

with

n

β‰₯

3 as a graph on

nm

+ 1 vertices consisting of a cycle

C

mn

and one

addi-tional vertex which is adjacent to

n

vertices of

C

mn

at

m

distance to each other

on

C

mn

. Let

V

(

J

m,n

) =

V

(

C

mn

)

βˆͺ {

u

1

}

or

V

(

J

m,n

) =

V

(

P

m

)

βˆͺ

V

(

W

n

) where

V

(

P

m

) =

{

v

1

, v

2

, . . . , v

n(mβˆ’1)

}

and

V

(

W

n

) =

{

u

1

, u

2

, . . . , u

n+1

}

, we have

V

(

J

m,n

) =

{

u

1

, u

2

, . . . , u

n+1

, v

1

, v

2

, . . . , v

n(mβˆ’1)

}

with

m, n

∈

N

.

Lemma 4.1.

Let

G

be a subgraph of a generalized Jahangir graph

J

m,n

for

m

β‰₯

3

,

n

β‰₯

3

and

Ξ 

is a resolving partition of

G

. The distance of vertex

u

1

to the other

vertices are

d

(

u

1

, u

i

) = 1

and

d

(

u

1

, v

k

) = 2

for

1

< i

≀

n

+ 1

and

1

≀

k

≀

n

(

m

βˆ’

1)

.

The distance of vertex

u

to the other vertex

u

are same,

d

(

u

i

, u

j

) = 2

for

1

< i

≀

n

+ 1

,

1

< j

≀

n

+ 1

and

i

ΜΈ

=

j

.

Proof.

Let

u

1

be a central vertex of

V

(

G

) =

V

(

J

m,n

). Since for each vertex

u

i

is

connected with central vertex, so

d

(

u

1

, u

i

) = 1 and

d

(

u

i

, u

j

) = 2 with 1

< i

≀

n

+ 1,

1

< j

≀

n

+ 1, and

i

ΜΈ

=

j

. If vertex

v

k

is vertex of path

P

m

and has minimum

distance of vertex

u

i

, then

d

(

u

1

, v

k

) = 2 for 1

≀

k

≀

n

(

m

βˆ’

1).

Theorem 4.1.

Let

J

m,n

be a generalized Jahangir graph for

m

β‰₯

3

and

n

β‰₯

3

then

pd

(

J

m,n

) =

{

3

,

for

n

= 3

,

4

,

5

;

⌊

n

2

βŒ‹

+ 1

,

for

n

β‰₯

6

.

(4)

Proof.

Let

J

m,n

be a generalized Jahangir graph for

m

β‰₯

3,

n

β‰₯

3 and a vertex set

V

(

J

m,n

). The proof can be divided into two cases according to the values of

n

.

(1) Case

n

= 3

,

4

,

5

(a) For

n

= 3

Let

a

=

{

v

1

, . . . , v

m

}

,

b

=

{

v

1

, . . . , v

mβˆ’1

}

,

c

=

{

v

m+1

, . . . , v

n(mβˆ’1)

}

, and

d

=

{

v

m

, . . . , v

2(mβˆ’1)

}

, then

S

1

=

{

u

1

, . . . , u

n+1

, v

2mβˆ’1

, . . . , v

mnβˆ’3

}

,

S

2

=

{

a,

for

m

= 3;

b,

for

m

β‰₯

4;

S

3

=

{

c,

for

m

= 3;

d,

for

m

β‰₯

4.

(b) For

n

= 4

Let

a

=

{

u

1

, . . . , u

n+2

, v

(n(mβˆ’1))βˆ’1

}

,

b

=

{

u

1

, . . . , u

n+2

, v

3mβˆ’2

, . . . , v

n(mβˆ’1)

}

,

c

=

{

u

1

, . . . , u

n+2

, v

2mβˆ’1

, v

3mβˆ’2

, . . . , v

n(mβˆ’1)

}

,

d

=

{

v

1

, . . . , v

m

}

,

e

=

{

v

1

, . . . , v

mβˆ’1

, v

2(m+1)

, v

m(nβˆ’1)βˆ’3

}

,

f

=

{

v

1

, . . . , v

mβˆ’1

, v

m(nβˆ’1)βˆ’3

}

,

g

=

{

v

m+1

, . . . , v

n(mβˆ’1)

}

,

h

=

{

v

m

, . . . , v

2(mβˆ’1)

, v

2mβˆ’1

, . . . , v

(mβˆ’1)(nβˆ’1)βˆ’1

}

,

i

=

{

v

m

, . . . , v

2(mβˆ’1)

, v

2m

, . . . , v

(mβˆ’1)(nβˆ’1)βˆ’1

}

, and

j

=

{

v

m

, . . . , v

2(mβˆ’1)

, v

2m

, v

2m+1

, v

2m+3

, . . . , v

(mβˆ’1)(nβˆ’1)βˆ’1

}

then

S

1

=

ο£±



ο£²



ο£³

a,

for

m

= 3;

b,

for

m

= 5;

c,

for

m

β‰₯

4

, m

ΜΈ

= 5;

S

2

=

ο£±



ο£²



ο£³

d,

for

m

= 3;

e,

for

m

= 9;

f,

for

m

β‰₯

4

, m

ΜΈ

= 9;

S

3

=

ο£±









ο£²









ο£³

g,

for

m

= 3;

h,

for

m

= 5;

i,

for

m

β‰₯

4

, m

ΜΈ

= 5

,

9;

j,

for

m

= 9.

For

n

= 5 is same as above. The representations of

r

(

u

|

Ξ ) and

r

(

v

|

Ξ ),

with

u, v

∈

V

(

J

m,n

) are

r

(

u

1

|

Ξ ) = (0

,

2

,

2),

r

(

u

2

|

Ξ ) = (0

,

1

,

3),

r

(

u

3

|

Ξ ) = (0

,

1

,

1),

r

(

u

n

|

Ξ ) = (0

,

3

,

1),

r

(

v

1

|

Ξ ) = (1

,

0

,

4),

r

(

v

2

|

Ξ ) = (2

,

0

,

5),

. . .

,

r

(

v

n(mβˆ’1)βˆ’1

|

Ξ ) = (0

,

3

,

5),

r

(

v

n(mβˆ’1)

|

Ξ ) = (0

,

2

,

4).

So the representation of

r

(

u

|

Ξ ) and

r

(

v

|

Ξ ) are distinct and we conclude

that Ξ  is a resolving partition of

J

m,n

with 3 elements. Furthermore, we

prove that there is no resolving partition with 2 elements. Suppose that

J

m,n

has a resolving partition with 2 elements, Ξ  =

{

S

1

, S

2

}

. Based

on Lemma 4.1, it is a contradiction. Therefore,

J

m,n

has no a resolving

(5)

partition with 2 elements. Thus, the partition dimension of

J

m,n

is

pd

(

J

m,n

) = 3 for

n

= 3

,

4

,

5.

(2) Case

n

β‰₯

6.

Let Ξ  =

{

S

1

, S

i

}

be a resolving partition of

J

m,n

where

S

1

=

{

u

i

, v

j

}

, for

1

≀

i

≀

n

+ 1, 1

≀

j

≀

n

(

m

βˆ’

1) and

S

i

=

{

v

k

}

, for 1

< i

≀ ⌊

n2

βŒ‹

+ 1

,

1

≀

k

≀

n

(

m

βˆ’

1)

, k

ΜΈ

=

j

. The representation for each vertex on

J

m,n

with respect to

Ξ  as follows

r

(

u

1

|

Ξ ) = (0

,

2

,

2

, . . . ,

2),

r

(

u

2

|

Ξ ) = (0

,

1

,

3

, . . . ,

3),

r

(

u

n+1

|

Ξ ) = (0

,

1

,

1

, . . . ,

3),

. . .

,

r

(

v

1

|

Ξ ) = (1

,

0

,

4

, . . . ,

4),

r

(

v

2

|

Ξ ) = (2

,

0

, . . . ,

5),

. . .

,

r

(

v

(mβˆ’1)

|

Ξ ) = (1

,

0

,

2

, . . . ,

4),

r

(

v

m

|

Ξ ) = (1

,

2

,

0

, . . . ,

4),

r

(

v

m+1

|

Ξ ) = (2

,

3

,

0

, . . . ,

5),

. . .

,

r

(

v

2(mβˆ’1)

|

Ξ ) = (1

,

4

,

2

,

0

, . . .

),

r

(

v

2m

|

Ξ ) = (2

,

5

,

3

,

0

, . . .

),

. . .

,

r

(

v

n(mβˆ’1)βˆ’1

|

Ξ ) = (0

,

2

,

5

, . . . ,

5),

r

(

v

n(mβˆ’1)

|

Ξ ) = (0

,

1

,

4

, . . . ,

4).

Since for each vertex of

J

m,n

has a distinct representation with respect to Ξ ,

so Ξ  is a resolving partition of

J

m,n

with

⌊

n2

βŒ‹

+ 1 elements.

Next, we show that the cardinality of Ξ  is

⌊

n

2

βŒ‹

+ 1. The cardinality of Ξ 

is the number of

k

βˆ’

partition in

S

1

and

S

i

for 1

< i

≀ ⌊

n2

βŒ‹

. The number of

k

βˆ’

partition in

S

1

is 1. The number of

k

βˆ’

partition in

S

i

for 1

< i

≀ ⌊

n

2

βŒ‹

is

⌊

n

2

βŒ‹

. We obtain

|

Ξ 

|

= 1+

⌊

n

2

βŒ‹

=

⌊

n

2

βŒ‹

+1. Therefore, Ξ  =

{

S

1

, S

2

, . . . , S

⌊n2βŒ‹+1

}

is a resolving partition of

J

m,n

.

We show that

J

m,n

has no

pd

(

J

m,n

)

<

⌊

n2

βŒ‹

+ 1. We may assume that Ξ  is

a resolving partition of

J

m,n

where

pd

(

J

m,n

)

<

⌊

n2

βŒ‹

+ 1. So, for each vertex

v

∈

V

(

J

m,n

) has a distinct representation

r

(

v

i

|

Ξ ) and

r

(

v

j

|

Ξ ). If we select

Ξ  =

{

S

1

, S

2

, S

3

, . . . , S

⌊n

2βŒ‹

}

as a resolving partition then there is a partition

class containing any 2 vertices of

v

j

. By using Lemma 4.1, the distance of

vertex

u

1

to the others have the same distance, and

r

(

v

i

|

Ξ ) =

r

(

v

j

|

Ξ ). It is a

contradiction. Hence, the partition dimension of

J

m,n

is

pd

(

J

m,n

) =

⌊

n2

βŒ‹

+ 1

for

n

β‰₯

6.

5.

The Partition Dimension of a

C

n

βˆ—

2

K

m

Graph

C

n

βˆ—

2

K

m

graph with

n

β‰₯

3 and

m

β‰₯

2 is a graph obtained from edge

amal-gamation, which combine an edge of

C

n

and an edge of

K

m

to be one incident

edge with vertex

x

and

y

. Vertex

x

and

y

also as owned by

C

n

and

K

m

. Let

V

(

C

n

βˆ—

2

K

m

) =

A

βˆͺ

B

βˆͺ{

x

}βˆͺ{

y

}

with

A

∈

V

(

C

n

)

\{

u

1

, u

2

}

and

B

∈

V

(

K

m

)

\{

v

1

, v

2

}

.

(6)

A vertex set

A

=

{

u

3

, u

4

, . . . , u

n

}

and

B

=

{

v

3

, v

4

, . . . , v

m

}

, vertex

x

=

u

1

βˆ—

v

1

and

y

=

u

2

βˆ—

v

2

, so

V

(

C

n

βˆ—

2

K

m

) =

{

x, y, u

3

, u

4

, . . . , u

n

, v

3

, v

4

, . . . , v

m

}

.

Lemma 5.1.

Let

G

be a subgraph of

C

n

βˆ—

2

K

m

graph for

n

β‰₯

3

,

m

β‰₯

2

and

Ξ 

is a resolving partition of

G

. Then the distance of vertex

x

and

y

to vertex

v

i

are

d

(

x, v

i

) =

d

(

y, v

i

) = 1

for

3

≀

i

≀

m

. Furthermore,

x

and

y

belong to distinct

elements of

Ξ 

.

Proof.

Let Ξ  =

{

S

1

, S

2

, . . . , S

m

}

be a resolving partition of

G

and

x, y, v

i

∈

G

. Since

vertex

x, y, v

i

∈

V

(

K

m

) with 3

≀

i

≀

m

, so the distance of vertex

x

and

y

to vertex

v

i

are

d

(

x, v

i

) =

d

(

y, v

i

) = 1 for 3

≀

i

≀

m

. Based on Lemma 2.2 then vertex

x

and

y

belong to distinct elements of Ξ .

Theorem 5.1.

Let

C

n

βˆ—

2

K

m

be a graph of resulting an edge amalgamation of

C

n

and

K

m

for

n

β‰₯

3

and

m

β‰₯

2

then

pd

(

C

n

βˆ—

2

K

m

) =

{

3

,

for

m

= 2

,

3

,

4

;

m

βˆ’

1

,

for

m

β‰₯

5

.

Proof.

Let

C

n

βˆ—

2

K

m

be a graph of resulting an edge amalgamation for

n

β‰₯

3 and

m

β‰₯

2. A vertex set

V

(

C

n

βˆ—

2

K

m

) where (

x, y

) are joining edge among edge (

u

1

, u

2

)

and (

v

1

, v

2

). The proof can be divided into two cases based on the values of

m

.

(1) Case

m

= 2

,

3

,

4.

According to Lemma 2.1, the partition dimensions of

C

n

βˆ—

2

K

m

are

pd

(

C

n

βˆ—

2

K

m

)

ΜΈ

= 2 and

pd

(

C

n

βˆ—

2

K

m

)

β‰₯

3.

(a) We prove that

pd

(

C

n

βˆ—

2

K

m

)

ΜΈ

= 2. Based on Lemma 2.1.1,

pd

(

G

) = 2 if

and only if

G

=

P

n

. Since

C

n

βˆ—

2

K

m

cannot be formed be a path, then

pd

(

C

n

βˆ—

2

K

m

)

ΜΈ

= 2.

(b) We show that the partition dimension of

C

n

βˆ—

2

K

m

is

pd

(

C

n

βˆ—

2

K

m

) = 3.

For each

v

∈

V

(

C

n

βˆ—

2

K

m

), let Ξ  =

{

S

1

, S

2

, S

3

}

be the resolving partition

where

S

1

=

{

x, v

3

}

,

S

2

=

{

y, v

4

}

, and

S

3

=

{

u

3

, . . . , u

n

}

. We obtain the

representation between all vertices of

V

(

C

n

βˆ—

2

K

m

) with respect to Ξ  as

follows

r

(

x

|

Ξ ) = (0

,

1

,

1),

r

(

y

|

Ξ ) = (1

,

0

,

1),

r

(

u

j

|

Ξ ) = (

d

(

u

j

, x

)

, d

(

u

j

, y

)

,

0),

r

(

v

3

|

Ξ ) = (0

,

1

,

2),

r

(

v

4

|

Ξ ) = (1

,

0

,

2),

for 3

≀

j

≀

n

with

d

(

u

j

, x

)

, d

(

u

j

, y

)

≀ ⌊

n2

βŒ‹

. Clearly that

r

(

x

|

Ξ )

ΜΈ

=

r

(

y

|

Ξ )

ΜΈ

=

r

(

u

3

|

Ξ )

ΜΈ

=

. . .

ΜΈ

=

r

(

u

n

|

Ξ )

ΜΈ

=

r

(

v

3

|

Ξ )

ΜΈ

=

. . .

ΜΈ

=

r

(

v

m

|

Ξ ), and then

the partition dimension of

C

n

βˆ—

2

K

m

is

pd

(

C

n

βˆ—

2

K

m

) = 3.

(2) Case

m

β‰₯

5

.

Let Ξ  =

{

S

1

, S

2

, . . . , S

mβˆ’1

}

be a resolving partition of

C

n

βˆ—

2

K

m

where

S

1

=

{

x, v

3

}

,

S

2

=

{

y, v

4

}

,

S

3

=

{

u

3

, . . . , u

n

}

, and

S

i

=

{

v

i+1

}

, with 3

< i

≀

m

βˆ’

1.

(7)

The representations of each vertex of

C

n

βˆ—

2

K

m

with respect to Ξ  are

r

(

x

|

Ξ ) = (0

,

1

,

1

, . . . ,

1),

r

(

y

|

Ξ ) = (1

,

0

,

1

, . . . ,

1),

r

(

u

3

|

Ξ ) = (2

,

1

,

0

, . . . , d

(

u

3

, v

i

)),

. . .

,

r

(

u

n

|

Ξ ) = (1

,

2

,

0

, . . . , d

(

u

n

, v

i

)),

r

(

v

3

|

Ξ ) = (0

,

1

,

2

, . . . ,

1),

. . .

,

r

(

v

m

|

Ξ ) = (1

,

0

,

2

, . . . ,

1),

with

d

(

u

3

|

Ξ )

, . . . , d

(

u

n

|

Ξ )

≀ ⌊

n2

βŒ‹

. Therefore, for each vertex

v

∈

V

(

C

n

βˆ—

2

K

m

)

has a distinct representation with respect to Ξ . So, the

C

n

βˆ—

2

K

m

graph has a

resolving partition with

m

βˆ’

1 elements. Next, we show that the cardinality

of Ξ  is

m

βˆ’

1. The cardinality of Ξ  is the number of

k

βˆ’

partition in

S

1

, S

2

, S

3

and

S

i

for 3

< i

≀

m

βˆ’

1. The number of

k

βˆ’

partition in

S

1

, S

2

and

S

3

are 1.

The number of

k

βˆ’

partition in

S

i

is

m

βˆ’

4, so

|

Ξ 

|

= 1+1+1+(

m

βˆ’

4) =

m

βˆ’

1.

Therefore, Ξ  =

{

S

1

, S

2

, . . . , S

mβˆ’1

}

is a resolving partition of

C

n

βˆ—

2

K

m

.

We show that

C

n

βˆ—

2

K

m

has no resolving partition with

m

βˆ’

2 elements.

Assume Ξ  is a resolving partition of

C

n

βˆ—

2

K

m

with

pd

(

C

n

βˆ—

2

K

m

)

< m

βˆ’

1 then

for each vertex

v

∈

V

(

C

n

βˆ—

2

K

m

) has a distinct representation. If we choose

Ξ  =

{

S

1

, S

2

, . . . , S

mβˆ’2

}

as a resolving partition then one of the partition class

contains 2 vertices

v

. By using Lemma 5.1, the distance of vertex

x

and

y

to vertex

v

i

, must be the same distance, and then vertex

x

and

y

belong

to distinct of partition class. As a result, we have the same representation

r

(

x

|

Ξ ) =

r

(

y

|

Ξ ), a contradiction. So, the partition dimension of

C

n

βˆ—

2

K

m

is

pd

(

C

n

βˆ—

2

K

m

) =

m

βˆ’

1 for

m

β‰₯

5.

6.

Conclusion

According to the discussion above it can be concluded that the partition

di-mension of a lollipop graph

L

m,n

, a generalized Jahangir graph

J

m,n

, and a

C

n

βˆ—

2

K

m

graph are as stated in Theorem 3.1, Theorem 4.1, and Theorem 5.1, respectively.

References

[1] Asmiati,Partition Dimension of Amalgamation of Stars, Bulletin of MathematicsVol 04no. 2 (2012), 161-167.

[2] Chartrand, G., E. Salehi, and P. Zhang,On the Partition Dimension of a Graph, Congressus NumerantiumVol. 131(1998), 55-66.

[3] Chartrand, G., E. Salehi, and P. Zhang, The Partition Dimension of a Graph, Aequation Math.Vol. 55(2000), 45-54.

[4] Danisa, O. L.,Dimensi Partisi pada Graf Flower, Graf3βˆ’Fold Wheel, dan Graf(KmΓ—Pn)βŠ™ K1, Tugas Akhir, Fakultas Matematika dan Ilmu Pengetahuan Alam, Universitas Sebelas Maret, Surakarta, 2015.

(8)

[5] Hidayat, D. W., Dimensi Partisi pada Beberapa Kelas Graf, Tugas Akhir, Fakultas Mate-matika dan Ilmu Pengetahuan Alam, Universitas Sebelas Maret, Surakarta, 2015.

[6] Javaid, I., and S. Shokat,On the Partition Dimension of Some Wheel Related Graph, Prime Research in MathematicsVol. 4(2008), 154-164.

[7] Mojdeh, D. A., and A. N. Ghameshlou,Domination in Jahangir GraphJ2,m, Int. J. Contemp. Math. SciencesVol. 2(24)(2007), 193199.

[8] Puspitaningrum, R. T., Dimensi Partisi pada Graf Closed Helm, Graf WnΓ—Pm, dan Graf CmβŠ™K1,n, Tugas Akhir, Fakultas Matematika dan Ilmu Pengetahuan Alam, Universitas

Sebelas Maret, Surakarta, 2015.

[9] Tomescu, I., I. Javaid, and Slamin, On the Partition Dimension and Connected Partition Dimension of Wheels, Ars Combinatoria Vol. 84(2007), 311-317.

[10] Weisstein, E. W.,CRC Concise Encyclopedia of Mathematics CD-ROM, 2nd ed., CRC Press, Boca Raton, 2003.

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