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The L(j, k)-Labeling Number and Circular L(j,k)-Labeling Number of Distance Graph Dn(1,5)

Received: 29 December 2024     Accepted: 14 January 2025     Published: 10 February 2025
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Abstract

For j ≤ k, the L(j, k)- labeling problem arose form the code assignment problem of the wireless network. That is, let n,j,k be non-negative real numbers with j ≤ k, an n-L(j, k)-labeling of a graph G is mapping f: V(G)→[0, n] such that |f(u)-f(v)| ≥ j if d(u, v)=1, and |f(u)-f(v)|≥k if t d(u, v)=2. The span of f is the difference between the maximum and minimum labeling numbers assigned by f. The L(j, k)-labeling number of graph G, denoted by λ(j,k) (G), is the minimum span of all L(j, k)-labeling of G. The infinite distance graph, denoted by D (d1,d2,…,dk), has the set Z of integers as a vertex set and in which two vertices i,j∈Z are adjacent if and only if |i-j|∈D. The finite distance graph, denoted by Dn (d1,d2,…,dk), is the subgraph of D(d1,d2,…,dk) induced by vertices {0,1,…,n-1}. This paper determines the L(j, k)-labeling number and the circular L(j, k)-labeling number of distance graph Dn (1,5) for 2j ≤ k.

Published in International Journal of Systems Science and Applied Mathematics (Volume 10, Issue 1)
DOI 10.11648/j.ijssam.20251001.12
Page(s) 7-11
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This is an Open Access article, distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution and reproduction in any medium or format, provided the original work is properly cited.

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Copyright © The Author(s), 2025. Published by Science Publishing Group

Keywords

The L(j, k)-labeling Number, The Circular L(j, k)-labeling Number, Code Assignment, Distance Graph

1. Introduction
For jk, the Lj,k-labeling, first introduced by Yeh , arose from the code assignment of wireless network proposed by Bertossi and Bonuccelli . A vertex and its label will represent a station and its corresponding code, respectively. If two stations can transmit to each other directly, their corresponding vertices are connected by an edge, for convenience, these two stations are called adjacent stations, and the two stations are at distance two if they are adjacent to a common station. To avoid the interferences in the wireless network, labels of vertices of a graph should satisfy some conditions. For example, a Packet Radio Network using CDMA has two types of interference: Direct interference and Secondary interference. Direct interference is caused by the adjacent stations, and stations at distance two cause the Secondary interference and direct interference simultaneously. In order to avoid these two types of interferences, the adjacent vertices are assigned labels whose difference is at least and vertices at distance two are assigned labels whose difference is at least k, where jk.
Let n,j,k be non-negative real numbers with jk, an n-Lj,k-labeling of a graph G is mapping f: VG0,n such that fu-fvj if d(u, v)=1, and fu-fvk if t d(u, v)=2. The span of f is the difference between the maximum and minimum labels assigned by f. The Lj,k-labeling number of graph G, denoted by λj,kG, is the minimum span of all Lj,k-labelings of G.
Lj,k-labeling numbers of some graphs for jk have been introduced in some literatures. For instance, Wu, Shiu and Sun investigated the Lj,k-labeling number of cartesian product graph of a path and a cycle, Wu also studied on Lj,k-labeling number of the strong product graph of path and cycle , wheel graph and Cactus graph . Guo and Wu determined the Lj,k-labeling numbers of book graph. Rao et al. studied the Lj,k-labeling numbers of cartesian product graph of arbitrary length of three paths with k>j in reference .
Heuvel et al. first introduced the circular Lj,k-labeling of a graph. They used the “circular distance” to instead of the “linear distance”, where the linear distance of two point a and b on the line is defined as |a-b|, and the circular distance of two points a and b on the cycle with circumference σ is defined as a-bσ=mina-b, σ-a-b.
Let σ be non-negative real numbers, a circular σ-Lj,k-labeling of a graph G is mapping f: VG0,σ such that fu-fvσj if d(u, v)=1, and fu-fvσk if d(u,v)=2. The circular Lj,k-labeling number of G, denoted by σj,k(G), is the minimum σ such that there exists a circular σ-Lj,k-labeling of G. The circular Lj,k-labeling number of graphs have been studied in several articles, please refer to .
Definition 1.1 Let D=d1,d2,,dk, where dii=1,2,,k are positive integers such that d1<d2<<dk. The (infinite) distance graph Dd1,d2,,dk has the set Z of integers as a vertex set and in which two vertices i,jZ are adjacent if and only if i-jD. The finite distance graph Dnd1,d2,,dk is the subgraph of Dd1,d2,,dk induced by vertices 0,1,,n-1.
Lemma 1.1 If graph H is an induced subgraph of graph G, then λj,kGλj,kH.
Lemma 1.2 Let j and k be two positive numbers with jk. Suppose is a graph and His an induced subgraph of G. Then σj,kGσj,kH.
Lemma 1.3 Suppose f is an Lj,k-labeling of graph G. Let
σ=maxmax dGu,v=2k+fu-fv,max dGu,v=1j+fu-fv.
If the image of f lies in [0,σ), then f is a circular σ- Lj,k-labeling of G.
2. Main Results
In this section, we mainly study on the Lj,k-labeling numbers and the circular Lj,k-labeling numbers of distance graph Dn(1,5) for n7 and k2j. For 1n5, the distance graph Dn(1,5) is isomorphic to path Pn, and D6(1,5) is isomorphic to the cycle C6. The Lj,k-labeling numbers and the circular Lj,k-labeling numbers of path and cycle have been discussed by Niu and Wu, Shiu and Sun , respectively, for k2j. For convenience, let G=Dn(1,5).
Theorem 2.1 Let n be an integer and j,k be non-negative real numbers with k2j. For 7n8, λj,kG=3k.
Proof: Define a labeling function f for the graph G as follows.
fi=ik, 0i3,[i+1]4k,4in-1.
As Figure 1 shows, it is not difficult to verify that f is an Lj,k-labeling of graph G with span(f)=3k, where that is, λj,kG3k.
Figure 1. The labeling f for distance graph D8(1,5).
On the other hand, any pair of vertices 0, 2, 4 and 6 are at distance two, according to the definition of Lj,k-labeling, it is at least k for the difference between any two labels of vertices 0, 2, 4 and 6, thus, λj,kG3k.
Hence, λj,kG=3k.
Theorem 2.2 Let n be an integer and j,k be non-negative real numbers with k2j. For n9, λj,kG=j+3k.
Proof: Given a labeling f for graph G as follows.
fi=i2j+i24k,0in-1.
For example, the labeling of D91,5 is shown in Figure 2.
Figure 2. The labeling f for distance graph D9(1,5).
For any vertex i, according to the symmetry of the distance graph, it is needed to verify the labels of vertices i+1 and i+5 which are adjacent to vertex i, and the labels of vertices i+2, i+4, i+6, i+10 which are 2 distance apart from vertex i.
1. The differences between fvi+1 and fvi, fvi+5 and fvi are shown as follows.
fvi+1-fvi=[i+1]2j+i+124k-[i]2j-i24k
=[i+1]2-[i]2j+i+124-i24k
=j, if i is even,k-j or j+3k,if i is odd,j.
fvi+5-fvi=[i+5]2j+i+524k-[i]2j-i24k
=[i+5]2-[i]2j+i+524-i24k
=j+2k or 2k-j,if i is even,j+k or 3k-j,if i is odd,j.
2. The differences between fvi+2 and fvi, fvi+4 and fvi, fvi+6 and fvi, fvi+10 and fvi are shown as follows.
fvi+2-fvi=[i+2]2j+i+224k-[i]2j-i24k
=[i+2]2-[i]2j+i+224-i24k
=k or 3kk.
fvi+4-fvi=[i+4]2j+i+424k-[i]2j-i24k
=[i+4]2-[i]2j+i+424-i24k
=2kk.
fvi+6-fvi=[i+6]2j+i+624k-[i]2j-i24k
=[i+6]2-[i]2j+i+624-i24k
=k or 3kk.
fvi+10-fvi=[i+10]2j+i+1024k-[i]2j-i24k
=[i+10]2-[i]2j+i+1024-i24k
=k or 3kk.
According to the above verification, f satisfies the definition of Lj,k-labeling, that is, f is an Lj,k-labeling of distance graph G with span(f)=j+3k, thus, λj,kGj+3k.
On the other hand, suppose λj,kG=λ<j+3k. Let f be an Lj,k-labeling of distance graph G, and I0=0,λ-3k, I1=k,λ-2k, I2=2k,λ-k, I3=3k,λ. Since vertices 0, 2, 4 and 6 are two distance apart from each other, the differences between any two of f0,f2,f4, f6 are at least k, that is, f0,f2,f4, f6i=03Ii. According to the assumption λ<j+3k, the lengths of interval Ii is less than j, where i=0,1,2,3. For convenience, let f0Ia, f2Ib, f4Ic, f6Id, where a,b,c,d=0,1,2,3. Moreover, vertices 2, 4, 6 and 8 are at distances two from each other, then f2,f4, f6,f8i=03Ii. It implies that f8,f0Ia. Furthermore, vertices 1, 3, 5 and 7 are also two distances apart mutually, then one of f1,f3,f5,f7 lies in Ia. However, each of vertices 1, 3, 5 and 7 is adjacent to v0 or v8, then f1,f3,f5,f7Ia which is a contradiction. Thus λj,kGj+3k.
Hence, λj,kG=j+3k.
Theorem 2.3 Let n be an integer and j,k be non-negative real numbers with k2j. For n7, σj,kG=4k.
Proof: Given an labeling f for graph G as follows.
fi=i24k,0in-1.
For any vertex i, according to the symmetry of the distance graph, it is needed to verify the labels of vertices i+1 and i+5 which are adjacent to vertex i, and the labels of vertices i+2, i+4, i+6, i+10 which are 2 distance apart from vertex i.
1. The circular distances between fvi+1 and fvi, fvi+5 and fvi are shown as follows.
fvi+1-fvi4k=i+124k-i24k4k
= k24k=mink2,4k-k2=k2,7k24k=min7k2,4k-7k2=k2,j.
fvi+5-fvi4k=i+524k-i24k4k
=5k24k=min5k2,4k-5k2=3k2,3k24k=min3k2,4k-3k2=3k2,j.
2. The circular distances between fvi+2 and fvi, fvi+4 and fvi, fvi+6 and fvi, fvi+10 and fvi are shown as follows.
fvi+2-fvi4k=i+224k-i24k4k
= k4k=mink,4k-k=k,3k4k=min3k,4k-3k=k,k.
fvi+4-fvi4k=i+424k-i24k4k
=2k4k=min2k,4k-2k=2kk.
fvi+6-fvi4k=i+624k-i24k4k
= k4k=mink,4k-k=k,3k4k=min3k,4k-3k=k,k.
fvi+10-fvi4k=i+1024k-i24k4k
= k4k=mink,4k-k=k,3k4k=min3k,4k-3k=k,k.
According to the above verification and Lemma 1.3, f is a circular 4k-Lj,k-labeling of distance graph G, thus, σj,kG4k for k2j.
On the other hand, any pair of vertices 0, 2, 4 and 6 are at distance two, according to the definition of circular Lj,k-labeling, the circular distance between any two labels of vertices 0, 2, 4 and 6 is at least k, thus, σj,kG4k.
Hence, σj,kG=4k for k2j.
3. Conclusion
In this article, we mainly investigate the Lj,k-labeling numbers and the circular Lj,k-labeling numbers of distance graph Dn(1,5) and obtain the following results.
Let n be an integer and j,k,σ be non-negative real numbers. Then
λj,kG= 3k, if 7n8.j+3k, if n9.
σj,kG=4k, where n7 and k2j.
Conflicts of Interest
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
References
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    Shuping, H., Qiong, W. (2025). The L(j, k)-Labeling Number and Circular L(j,k)-Labeling Number of Distance Graph Dn(1,5). International Journal of Systems Science and Applied Mathematics, 10(1), 7-11. https://doi.org/10.11648/j.ijssam.20251001.12

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    Shuping, H.; Qiong, W. The L(j, k)-Labeling Number and Circular L(j,k)-Labeling Number of Distance Graph Dn(1,5). Int. J. Syst. Sci. Appl. Math. 2025, 10(1), 7-11. doi: 10.11648/j.ijssam.20251001.12

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    Shuping H, Qiong W. The L(j, k)-Labeling Number and Circular L(j,k)-Labeling Number of Distance Graph Dn(1,5). Int J Syst Sci Appl Math. 2025;10(1):7-11. doi: 10.11648/j.ijssam.20251001.12

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  • @article{10.11648/j.ijssam.20251001.12,
      author = {He Shuping and Wu Qiong},
      title = {The L(j, k)-Labeling Number and Circular L(j,k)-Labeling Number of Distance Graph Dn(1,5)},
      journal = {International Journal of Systems Science and Applied Mathematics},
      volume = {10},
      number = {1},
      pages = {7-11},
      doi = {10.11648/j.ijssam.20251001.12},
      url = {https://doi.org/10.11648/j.ijssam.20251001.12},
      eprint = {https://article.sciencepublishinggroup.com/pdf/10.11648.j.ijssam.20251001.12},
      abstract = {For j ≤ k, the L(j, k)- labeling problem arose form the code assignment problem of the wireless network. That is, let n,j,k be non-negative real numbers with j ≤ k, an n-L(j, k)-labeling of a graph G is mapping f: V(G)→[0, n] such that |f(u)-f(v)| ≥ j if d(u, v)=1, and |f(u)-f(v)|≥k if t d(u, v)=2. The span of f is the difference between the maximum and minimum labeling numbers assigned by f. The L(j, k)-labeling number of graph G, denoted by λ(j,k) (G), is the minimum span of all L(j, k)-labeling of G. The infinite distance graph, denoted by D (d1,d2,…,dk), has the set Z of integers as a vertex set and in which two vertices i,j∈Z are adjacent if and only if |i-j|∈D. The finite distance graph, denoted by Dn (d1,d2,…,dk), is the subgraph of D(d1,d2,…,dk) induced by vertices {0,1,…,n-1}. This paper determines the L(j, k)-labeling number and the circular L(j, k)-labeling number of distance graph Dn (1,5) for 2j ≤ k.},
     year = {2025}
    }
    

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  • TY  - JOUR
    T1  - The L(j, k)-Labeling Number and Circular L(j,k)-Labeling Number of Distance Graph Dn(1,5)
    AU  - He Shuping
    AU  - Wu Qiong
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    DO  - 10.11648/j.ijssam.20251001.12
    T2  - International Journal of Systems Science and Applied Mathematics
    JF  - International Journal of Systems Science and Applied Mathematics
    JO  - International Journal of Systems Science and Applied Mathematics
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    PB  - Science Publishing Group
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    UR  - https://doi.org/10.11648/j.ijssam.20251001.12
    AB  - For j ≤ k, the L(j, k)- labeling problem arose form the code assignment problem of the wireless network. That is, let n,j,k be non-negative real numbers with j ≤ k, an n-L(j, k)-labeling of a graph G is mapping f: V(G)→[0, n] such that |f(u)-f(v)| ≥ j if d(u, v)=1, and |f(u)-f(v)|≥k if t d(u, v)=2. The span of f is the difference between the maximum and minimum labeling numbers assigned by f. The L(j, k)-labeling number of graph G, denoted by λ(j,k) (G), is the minimum span of all L(j, k)-labeling of G. The infinite distance graph, denoted by D (d1,d2,…,dk), has the set Z of integers as a vertex set and in which two vertices i,j∈Z are adjacent if and only if |i-j|∈D. The finite distance graph, denoted by Dn (d1,d2,…,dk), is the subgraph of D(d1,d2,…,dk) induced by vertices {0,1,…,n-1}. This paper determines the L(j, k)-labeling number and the circular L(j, k)-labeling number of distance graph Dn (1,5) for 2j ≤ k.
    VL  - 10
    IS  - 1
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