PARADIGMA BARU PENDIDIKAN MATEMATIKA DAN APLIKASI ONLINE INTERNET PEMBELAJARAN How to cite: N. A. Sudibyo, A. Iswardani , and Y. P. S. R. Hidayat, β€œTotal Vertex Irregularity Strength of Disjoint Union of Ladder Rung Graph and Disjoint Union of Domino Graph”, JMM, vol. 6, no. 1, pp. 47-51, May 2020. Total Vertex Irregularity Strength of Disjoint Union of Ladder Rung Graph and Disjoint Union of Domino Graph Nugroho Arif Sudibyo1, Ardymulya Iswardani2, Yohana Putra Surya Rahmad Hidayat3 1Department of Informatics Engineering, Universitas Duta Bangsa, nugroho_arif@udb.ac.id 2Department of Information Systems, Universitas Duta Bangsa, ardymulya@udb.ac.id 3SMK Negeri 2 Kudus, yohan.artup@gmail.com doi: https://doi.org/10.15642/mantik.2020.6.1.47-51 Abstrak: Akan diselidiki pelabelan graf yang disebut total vertex irregularity strength (tvs(G)). tvs(G) adalah minimum π’Œ yang graf tersebut memenuhi pelabelan π’Œ-total titik tidak teratur. Pada makalah ini, akan ditentukan pelabelan total tak reguler titik dari graf disjoint union of ladder rung dan graf disjoint union of domino graph. Kata kunci: Graf; tvs; Ladder rung; Domino Abstract: We investigate a graph labeling called the total vertex irregularity strength (tvs(G)). A tvs(G) is minimum π’Œ for which graph has a vertex irregular total π’Œ-labeling. In this paper, we determine the total vertex irregularity strength of disjoint union of ladder rung graph and disjoint union of domino graph. Keywords: Graph; tvs; Ladder rung; Domino Jurnal Matematika MANTIK Volume 6, No.1, May 2020, pp. 47-51 ISSN: 2527-3159 (print) 2527-3167 (online) mailto:yohan.artup@gmail.com http://u.lipi.go.id/1458103791 http://u.lipi.go.id/1457054096 Jurnal Matematika MANTIK Volume 6, Issue. 1, May 2020, pp. 47-51 48 1. Introduction In 1735, graph theory was first introduced by Leonhard Euler to solve the problem of the Konigsberg bridge on the river Pregel, Russia [1]. Graph labeling is an interesting topic in graph theory so that various types of labeling are researched and developed [2]. Graph labeling is the assignment of labels to the graph elements such as edges or vertices, or both, from the graph [3]. Graph labeling can be applied to various fields including transportation systems, communication systems, geographical navigation, radar, and also security systems. For example, the design of the code for radar signals and missiles is equivalent to labeling a complete graph, where each point is connected to one side which has a label that is always different. This side label describes the distance between points, while the point label is the position at the time the signal is sent [4]. For a graph 𝐺(𝑉,𝐸), a labeling 𝑓:𝑉(𝐺) βˆͺ 𝐸(𝐺) β†’ {1,2,…,π‘˜} to be a vertex irregular total π‘˜-labeling if for any two different vertices x and y, their weights satisfy 𝑀𝑑𝑓(π‘₯) β‰  𝑀𝑑𝑓(𝑦) (see [5], [6]). The total vertex irregularity strength is minimum π‘˜ for which graph has a vertex irregular total π‘˜-labeling (see [6], [7]). The total vertex irregularity strength problem has been investigated for trees [8], 𝐢𝑛 βˆ—2 𝐾𝑛 graph [9], regular graph [10], forest graph [11], disjoint union of sun graph [5], wheel related graphs [12], graph obtained of a star [13], trees with maximum degree five [14], and comb product of two cycles and two stars [15]. In this paper we answer the open problem proposed by Baca, et.al [7]. In particular, we determine the total vertex irregularity strength of disjoint union of ladder rung graph and disjoint union of domino graph. 2. Preliminaries Ball and Coxeter define the ladder graph 𝑛𝑃2, is 𝑛 copies of the path graph 𝑃2 [4]. The ladder rung graph can be depicted as in Figure 1. Figure 1. The ladder rung graph Theorem 1. The total vertex irregularity strength of disjoint union of ladder rung graph is 𝑑𝑣𝑠(𝑑𝐿𝑛) = 𝑛𝑑 + 1, for 𝑛 β‰₯ 1, 𝑑 β‰₯ 2. Proof. The disjoint union of ladder rung graph 𝑑𝐿𝑛 has 2𝑛𝑑 vertices. The smallest 𝑀𝑑(𝑑𝐿𝑛) must be 2 and the largest 𝑀𝑑(𝑑𝐿𝑛) is at least 𝑛𝑑 + 1. Because of every vertex has degree one, then 𝑑𝑣𝑠(𝑑𝐿𝑛) β‰₯ 𝑛𝑑 + 1. To show that 𝑑𝑣𝑠(𝑑𝐿𝑛) ≀ 𝑛𝑑 + 1. The label of vertices of 𝑑𝐿𝑛 are described in the following formulas: πœ†(𝑒𝑖) = 𝑖, for 𝑖 ∈ [1,𝑛𝑑], πœ†(𝑣𝑖) = 𝑖+1, for 𝑖 ∈ [1,𝑛𝑑]. Then, the label of edges of 𝑑𝐿𝑛 are 1 u 2u nu 1v 2v nv N. A. Sudibyo, A. Iswardani , and Y. P. S. R. Hidayat, Total Vertex Irregularity Strength of Disjoint Union of Ladder Rung Graph and Disjoint Union of Domino Graph 49 πœ†(𝑣𝑖𝑣𝑖) = 𝑖+1, for 𝑖 ∈ [1,𝑛𝑑]. The weights of vertices 𝑒𝑖 and 𝑣𝑖 of 𝑑𝐿𝑛 are: 𝑀𝑑(𝑒𝑖) = 2𝑖 + 1, for 𝑖 ∈ [1,𝑛𝑑], 𝑀𝑑(𝑣𝑖) = 2(𝑖 + 1), for 𝑖 ∈ [1,𝑛𝑑]. The weights calculated at vertices are distinct. So, 𝑑𝑣𝑠(𝑑𝐿𝑛) = 𝑛𝑑 + 1, for 𝑛 β‰₯ 1, 𝑑 β‰₯ 2. 3. Results The domino graph is (2,3)-grid graph [16]. The disjoint union of domino graph can be depicted as in Figure 2. Figure 2. The disjoint union of domino graph Theorem 2. The total vertex irregularity strength of disjoint union of domino graph is 𝑑𝑣𝑠(𝑛𝐷) = 𝑛 + 1. Proof. The disjoint union of ladder rung graph 𝑛𝐷 has 6𝑛 vertices. The smallest 𝑀𝑑(𝑛𝐷) must be 3 and the largest 𝑀𝑑(𝑛𝐷)at least 3𝑛 + 5. It easy to see that 𝑑𝑣𝑠(𝑛𝐷) β‰₯ 𝑛 + 1. To show that 𝑑𝑣𝑠(𝑛𝐷) ≀ 𝑛 + 1. The label of vertices of 𝑛𝐷 are: πœ†(𝑒𝑖,1) = 𝑖, for 𝑖 ∈ [1,𝑛], πœ†(𝑒𝑖,2) = 𝑖, for 𝑖 ∈ [1,𝑛], πœ†(𝑒𝑖,3) = 2, for 𝑖 ∈ [1,𝑛], πœ†(𝑒𝑖,4) = 2, for 𝑖 ∈ [1,𝑛], πœ†(𝑒𝑖,5) = 𝑖, for 𝑖 ∈ [1,𝑛], πœ†(𝑒𝑖,6) = 𝑖 + 1, for 𝑖 ∈ [1,𝑛]. Then, the label of edges of 𝑛𝐷 are πœ†(𝑒𝑖,1𝑒𝑖,2) = 𝑖, for 𝑖 ∈ [1,𝑛], πœ†(𝑒𝑖,1𝑒𝑖,3) = 𝑖, for 𝑖 ∈ [1,𝑛], πœ†(𝑒𝑖,2𝑒𝑖,3) = 𝑖 + 1, for 𝑖 ∈ [1,𝑛], πœ†(𝑒𝑖,3𝑒𝑖,4) = 𝑖 + 1, for 𝑖 ∈ [1,𝑛], πœ†(𝑒𝑖,3𝑒𝑖,5) = 𝑖 + 1, for 𝑖 ∈ [1,𝑛], πœ†(𝑒𝑖,4𝑒𝑖,6) = 𝑖 + 1, for 𝑖 ∈ [1,𝑛], πœ†(𝑒𝑖,5𝑒𝑖,6) = 𝑖 + 1, for 𝑖 ∈ [1,𝑛]. The weights of vertices 𝑒𝑖 and 𝑣𝑖 of 𝑑𝐿𝑛 (respectively) are: Jurnal Matematika MANTIK Volume 6, Issue. 1, May 2020, pp. 47-51 50 𝑀𝑑(𝑒𝑖,1) = 3𝑛, for 𝑖 ∈ [1,𝑛], 𝑀𝑑(𝑒𝑖,2) = 3𝑛 + 1, for 𝑖 ∈ [1,𝑛], 𝑀𝑑(𝑒𝑖,3) = 3𝑛 + 4, for 𝑖 ∈ [1,𝑛], 𝑀𝑑(𝑒𝑖,4) = 3𝑛 + 5, for 𝑖 ∈ [1,𝑛], 𝑀𝑑(𝑒𝑖,5) = 3𝑛 + 2, for 𝑖 ∈ [1,𝑛], 𝑀𝑑(𝑒𝑖,6) = 3(𝑛 + 1), for 𝑖 ∈ [1,𝑛]. The weights calculated at vertices are distinct. So, 𝑑𝑣𝑠(𝑛𝐷) = 𝑛 + 1. 4. Conclusions The total vertex irregularity strength of disjoint union of ladder rung graph is 𝑑𝑣𝑠(𝑑𝐿𝑛) = 𝑛𝑑 + 1, for 𝑛 β‰₯ 1, 𝑑 β‰₯ 2 and the total vertex irregularity strength of disjoint union of domino graph is 𝑑𝑣𝑠(𝑛𝐷) = 𝑛 + 1. References [1] N. A. Sudibyo and S. Komsatun, β€œPelabelan total tak reguler pada graf barbel,” J. Math. Math. Educ., vol. 8, no. 1, pp. 16–19, 2018. [2] J. A. Gallian, β€œA dynamic survey of graph labeling,” Electron. J. Comb., vol. 1, no. DynamicSurveys, 2018. [3] M. Marsidi and I. H. Agustin, β€œThe local antimagic on disjoint union of some family graphs,” J. 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