On the Dominant Local Resolving Set of Vertex Amalgamation Graphs CAUCHY โ€“Jurnal Matematika Murni dan Aplikasi Volume 7(4) (2023), Pages 597-607 p-ISSN: 2086-0382; e-ISSN: 2477-3344 Submitted: December 19, 2022 Reviewed: December 20, 2022 Accepted: March 16, 2023 DOI: http://dx.doi.org/10.18860/ca.v7i4.18891 On the Dominant Local Resolving Set of Vertex Amalgamation Graphs Reni Umilasari1,2, Liliek Susilowati1,*, Slamin3, Savari Prabhu4 1,2 Department of Mathematics, Airlangga University, Surabaya 60115, Indonesia 2Department of Informatics Engineering, University of Muhammadiyah Jember, Jember 69121 Indonesia 3Study Program of Informatics, University of Jember, Jember 68121 Indonesia 4Mathematics Department, Rajalakshmi Engineering College, Chennai 602105, Tamil Nadu, India Email: liliek-s@fst.unair.ac.id ABSTRACT In graph theory, there is a new topic of the dominant local metric dimension which be symbolized by ๐ท๐‘‘๐‘–๐‘š๐‘™ (๐ป) and it was a combination of local metric dimension and dominating set. There are some terms in this topic that is dominant local resolving set and dominant local basis. An ordered subset ๐‘Š๐‘™ is said a dominant local resolving set of ๐บ if ๐‘Š๐‘™ is dominating set and also local resolving set of ๐บ. While dominant local basis is a dominant local resolving set with minimum cardinality. This study uses literature study method by observing the local metric dimension and dominating number before detecting the dominant local metric dimension of the graphs. After obtaining some new results, the purpose of this research is how the dominant local metric dimension of vertex amalgamation product graphs. Some special graphs that be used are star, friendship, complete graph and complete bipartite graph. Based on all observation results, it can be said that the dominant local metric dimension for any vertex amalgamation product graph depends on the dominant local metric dimension of the copied graphs and how the terminal vertex is constructed. Copyright ยฉ 2023 by Authors, Published by CAUCHY Group. This is an open access article under the CC BY- SA License (https://creativecommons.org/licenses/by-sa/4.0/) Keywords: dominant local metric dimension; vertex amalgamation; star; friendship; complete bipartite INTRODUCTION Metric dimension and dominating set are graph topics with numerous variations. For metric dimensions, there are more than five development concepts, such as partition dimension, local metric dimension, complement metric dimension, central metric dimension, fractional metric dimension, and star metric dimension. More results about metric dimension and its expansion can be seen at [1] about the simultaneous local metric dimension, the local metric dimension of amalgamation [2] and corona product of star and path graph [3] , complement metric dimension [4], fractional metric dimension [5], and the new one is star metrc dimension [6]. Let ๐บ be a connected graph with vertex set ๐‘‰(๐บ) and edge set ๐ธ(๐บ). The distance between any two ๐‘Ž and ๐‘ of ๐‘‰(๐บ) is denoted by ๐‘‘(๐‘Ž, ๐‘). It be defined as shortest path from ๐‘Ž to ๐‘. The resolving set of ๐บ is an ordered set which can be written as ๐‘Š, where ๐‘Š = {๐‘ค1, ๐‘ค2, โ€ฆ , ๐‘ค๐‘˜ } โŠ† ๐‘‰(๐บ) and ๐‘Ÿ(๐‘ฃ|๐‘Š) = (๐‘‘(๐‘ฃ, ๐‘ค1), ๐‘‘(๐‘ฃ, ๐‘ค2), โ€ฆ . , ๐‘‘(๐‘ฃ, ๐‘ค๐‘˜ )) is defined as http://dx.doi.org/10.18860/ca.v7i4.18891 mailto:liliek-s@fst.unair.ac.id https://creativecommons.org/licenses/by-sa/4.0/ On the Dominant Local Resolving Set of Vertex Amalgamation Graphs Reni Umilasari 598 representation of ๐‘ฃ โŠ† ๐‘‰(๐บ) to ๐‘Š by using the concept of distance. The rule to select resolving set of ๐บ is every vertex of ๐‘‰(๐บ) should have different representation to ๐‘Š. The minimum cardinality of ๐‘Š is called the basis of ๐บ [7]. The number of basis is referred to the metric dimension because the concept of this topic is based on distance. Next, we introduce the differences between metric dimension and local metric dimension. In the metric dimension, all vertices must have different representations to the resolving set, whereas in the local metric dimension, only any two adjacent vertices must be different. It also can be said that a vertex's representation can be the same as another vertices even though they are not adjacent. [8]. Some examples of the local metric dimension have been published at [9], [10] and [11]. More clearly, there is a paper which describe the similarity between metric dimension and the local metric dimension [12]. In 2021, Umilasari et al introduced the new concept, which is a combination of dominating set and local metric dimension. They defined that an ordered subset ๐‘Š๐‘™ is said a dominant local resolving set of ๐บ if ๐‘Š๐‘™ is dominating set and also local resolving set of ๐บ. For a clearer understanding of this term, you can see the illustration in Figure 1. All the vertices in the graph of Figure 1 (a) can be dominated by ๐‘ฅ4. But the vertices which adjacent {๐‘‰(๐บ)\๐‘ฅ4} have same representation to ๐‘ฅ4. While {๐‘ฅ2, ๐‘ฅ3} in Figure 1 (b) is a local resolving set. As can be seen, each pair of adjacent vertices has a different representation to {๐‘ฅ2, ๐‘ฅ3}. The problem is ๐‘ฅ5 and ๐‘ฅ6 cannot be dominated by ๐‘ฅ2 or ๐‘ฅ3. If we take two vertices like in Figure 1(c), {๐‘ฅ2, ๐‘ฅ4} can dominate all vertices of the graph, the representation of any two vertices to {๐‘ฅ2, ๐‘ฅ4} is different. Therefore, {๐‘ฅ2, ๐‘ฅ4} are elements of a dominant local metric dimension of the graph. Figure 1. The Illustration of Dominant Local Metric Dimension of Graphs After obtaining some new results, in this paper we continue to expand on how the dominant local metric dimension of a vertex amalgamation product graphs. The vertex amalgamation product of a graph ๐ป, denoted by ๐‘Ž๐‘š๐‘Ž๐‘™(๐ป, ๐‘ฃ, ๐‘˜), is defined as creating a new graph by gluing ๐‘˜-copies of ๐ป in a terminal vertex ๐‘ฃ [13]. In this paper, we determine the dominant local metric dimension of the vertex amalgamation for some special graphs, which are star, complete graph, complete bipartite graph, and friendship graph. To make it easier to present each of the theorems produced, several theorems are given below, which can be seen in [14]. Lemma 1. Let ๐บ be a connected graph. If there is no local dominant resolving set with cardinality ๐‘, then for every ๐‘† โŠ† ๐‘‰(๐บ) with |๐‘†| < ๐‘ is not a local dominant resolving set. Lemma 2. Let ๐บ be a connected graph and ๐‘Š๐‘™ โŠ† ๐‘‰(๐บ). For every ๐‘ฃ๐‘– , ๐‘ฃ๐‘— โˆˆ ๐‘Š๐‘™ then ๐‘Ÿ(๐‘ฃ๐‘– |๐‘Š๐‘™ ) โ‰  ๐‘Ÿ(๐‘ฃ๐‘— |๐‘Š๐‘™ ). Some new results about the dominant local metric dimension of star, complete On the Dominant Local Resolving Set of Vertex Amalgamation Graphs Reni Umilasari 599 graph, complete bipartite graph, and friendship graph are given in Table 1. On the Dominant Local Resolving Set of Vertex Amalgamation Graphs Reni Umilasari 600 Table 1. Dominant Local Metric Dimension of Special Graphs [14][15][16] Graphs Dominating Number (๐œธ(๐‘ฎ)) Local Metric Dimension (๐๐ข๐ฆ๐’(๐‘ฎ)) Dominan Local Metric Dimension (๐๐ข๐ฆ๐’(๐‘ฎ)) Star (๐‘†๐‘›) ๐›พ (๐‘†๐‘›) = 1 dim๐‘™ (๐‘†๐‘›) = 1 Ddim๐‘™ (๐‘†๐‘›) = 1 Complete (๐พ๐‘›) ๐›พ (๐พ๐‘›) = 1 dim๐‘™ (๐พ๐‘›) = ๐‘› โˆ’ 1 Ddim๐‘™ (๐พ๐‘›) = ๐‘› โˆ’ 1 Complete Bipartite (๐พ๐‘š,๐‘›) ๐›พ(๐พ๐‘š,๐‘›) = 2 dim๐‘™ (๐พ๐‘š,๐‘›) = 2 Ddim๐‘™ (๐พ๐‘š,๐‘›) = 2 Friendship (๐น๐‘› ) ๐›พ(๐น๐‘› ) = 1 dim๐‘™ (๐น๐‘›) = ๐‘› Ddim๐‘™ (๐น๐‘›) = ๐‘› METHODS In this research, there are several procedures. We start by determining the special graphs to be operated by the vertex amalgamation product and observing the local metric dimensions and dominating number of the graphs. Then, we construct the vertex amalgamation product graphs from the special graphs that we have chosen. We continue by labeling the vertex and attempting to find the least dominant local basis. This is accomplished by observing and recording the representation of each vertex which can be dominated and has different representation from the local resolving set (two non- neighbouring vertex can have the same representation). The minimum local dominant basis is then determined. In summary, the procedures of the research can be seen in the following flowchart in Figure 2. We also give some examples of each step below. a) Let ๐บ = ๐‘ƒ4 b) ๐‘‘๐‘–๐‘š๐‘™ (๐‘ƒ4) = 1 and ๐›พ(๐‘ƒ4) = 2 , it can be seen at [16] c) Let |๐‘Š๐‘™ | = 1, ๐‘Š๐‘™ = {๐‘ฃ1} Illustration: Based on the illustration above, ๐‘ฃ1 canโ€™t dominate ๐‘ฃ3 and ๐‘ฃ4. When we choose ๐‘Š๐‘™ = {๐‘ฃ2}, ๐‘Š๐‘™ = {๐‘ฃ3}, ๐‘Š๐‘™ = {๐‘ฃ4} the condition remains the same. Minimally, there exist one vertex that canโ€™t be dominated. d) Let |๐‘Š๐‘™ | = 2, ๐‘Š๐‘™ = {๐‘ฃ1, ๐‘ฃ2} Illustration: We can see that ๐‘ฃ4 canโ€™t be dominated by ๐‘ฃ1 or ๐‘ฃ2 . e) Let |๐‘Š๐‘™ | = 2, ๐‘Š๐‘™ = {๐‘ฃ2, ๐‘ฃ3} Illustration: Since โˆ€๐‘ฃ๐‘– ๐‘ฃ๐‘— โˆˆ ๐ธ(๐‘ƒ4), ๐‘Ÿ(๐‘ฃ๐‘– |๐‘Š๐‘™ ) โ‰  ๐‘Ÿ(๐‘ฃ๐‘— |๐‘Š๐‘™ ) then ๐‘Š๐‘™ is basis local of ๐‘ƒ4. All vertices of ๐‘‰(๐‘ƒ4) can be dominated by ๐‘ฃ2 and ๐‘ฃ3. Therefore, ๐‘Š๐‘™ is dominant local basis of ๐‘ƒ4 or ๐ท๐‘‘๐‘–๐‘š๐‘™ (๐‘ƒ4) = 2. To more clearly understand this research method, we can see the flowchart in Figure 2. On the Dominant Local Resolving Set of Vertex Amalgamation Graphs Reni Umilasari 601 Figure 2. Flowchart for Determining the Minimum Dominant Local Resolving Set of Graphs RESULTS AND DISCUSSION In this section, we determine the dominant local metric dimension of the vertex amalgamation product for some special graphs, which are star, complete graph, complete bipartite graph, and friendship graph. Theorem 1. Let ๐‘Ž๐‘š๐‘Ž๐‘™(๐‘†๐‘›, ๐‘ฃ, ๐‘˜) is a vertex amalgamation of star with the order of star is ๐‘› โ‰ฅ 3, then ๐ท๐‘‘๐‘–๐‘š๐‘™ (๐‘Ž๐‘š๐‘Ž๐‘™(๐‘†๐‘›, ๐‘ฃ, ๐‘˜)) = { 1, ๐‘ฃ ๐‘–๐‘  ๐‘๐‘’๐‘›๐‘ก๐‘’๐‘Ÿ ๐‘ฃ๐‘’๐‘Ÿ๐‘ก๐‘’๐‘ฅ ๐‘œ๐‘“ ๐‘†๐‘› ๐‘˜, ๐‘ฃ ๐‘–๐‘  ๐‘๐‘’๐‘›๐‘‘๐‘Ž๐‘›๐‘ก ๐‘œ๐‘“ ๐‘†๐‘› On the Dominant Local Resolving Set of Vertex Amalgamation Graphs Reni Umilasari 602 Proof. Case 1. ๐‘ฃ is center vertex of star It is very clearly to see that ๐‘Ž๐‘š๐‘Ž๐‘™(๐‘†๐‘›, ๐‘ฃ, ๐‘˜) โ‰… ๐‘†๐‘›, then by the Table 1 we can conclude that ๐ท๐‘‘๐‘–๐‘š๐‘™ (๐‘Ž๐‘š๐‘Ž๐‘™(๐‘†๐‘›, ๐‘ฃ, ๐‘˜)) = 1. โˆŽ Case 2. ๐‘ฃ is pendant vertex of star Let the vertex set of ๐‘Ž๐‘š๐‘Ž๐‘™(๐‘†๐‘›, ๐‘ฃ, ๐‘˜) is ๐‘‰(๐‘Ž๐‘š๐‘Ž๐‘™(๐‘†๐‘›, ๐‘ฃ, ๐‘˜)) = {๐‘ฃ, ๐‘ฃ๐‘— , ๐‘ข1๐‘— , ๐‘ข2๐‘— , โ€ฆ , ๐‘ข๐‘–๐‘— |๐‘ฃ, ๐‘ข๐‘– โˆˆ ๐‘‰(๐‘†๐‘›), ๐‘– = 1,2, โ€ฆ , ๐‘› โˆ’ 2, ๐‘— = 1,2, โ€ฆ , ๐‘˜} and the edge set is ๐ธ(๐‘Ž๐‘š๐‘Ž๐‘™(๐‘†๐‘›, ๐‘ฃ, ๐‘˜)) = {๐‘ฃ๐‘ฃ๐‘— , ๐‘ฃ๐‘— ๐‘ข๐‘–๐‘— |๐‘– = 1,2,3, โ€ฆ , ๐‘› โˆ’ 2, ๐‘— = 1,2,3, โ€ฆ , ๐‘˜}. Choose ๐‘Š๐‘™ = {๐‘ฃ๐‘— } is the local basis of ๐‘Ž๐‘š๐‘Ž๐‘™(๐‘†๐‘›, ๐‘ฃ, ๐‘˜) for every ๐‘— = 1,2,3, โ€ฆ , ๐‘˜, |๐‘Š๐‘™ | = ๐‘˜. We can show below that the representation of every two adjacent vertices of ๐‘‰(๐‘Ž๐‘š๐‘Ž๐‘™(๐‘†๐‘›, ๐‘ฃ, ๐‘˜)) is different. i. For ๐‘ข๐‘–๐‘— ๐‘ฃ๐‘— โˆˆ ๐ธ(๐‘Ž๐‘š๐‘Ž๐‘™(๐‘†๐‘›, ๐‘ฃ, ๐‘˜)) Since ๐‘ฃ๐‘— is element of ๐‘Š๐‘™ , then there exist 0 on ๐‘– th element in ๐‘Ÿ(๐‘ฃ๐‘— |๐‘Š๐‘™ ), while for ๐‘Ÿ(๐‘ข๐‘–๐‘— |๐‘Š๐‘™ ) there are no zero elements, hence ๐‘Ÿ(๐‘ฃ๐‘— |๐‘Š๐‘™ ) โ‰  ๐‘Ÿ(๐‘ข๐‘–๐‘— |๐‘Š๐‘™ ). ii. For ๐‘ฃ๐‘ฃ๐‘— โˆˆ ๐ธ(๐‘Ž๐‘š๐‘Ž๐‘™(๐‘†๐‘›, ๐‘ฃ, ๐‘˜)) Since ๐‘ฃ๐‘— is element of ๐‘Š๐‘™ , then there exist 0 on ๐‘– th element in ๐‘Ÿ(๐‘ฃ๐‘— |๐‘Š๐‘™ ), while for ๐‘Ÿ(๐‘ฃ|๐‘Š๐‘™ ) there are no zero elements, hence ๐‘Ÿ(๐‘ฃ๐‘— |๐‘Š๐‘™ ) โ‰  ๐‘Ÿ(๐‘ฃ|๐‘Š๐‘™ ). By i and ii therefore ๐‘Š๐‘™ is a local resolving set of ๐‘Ž๐‘š๐‘Ž๐‘™(๐‘†๐‘›, ๐‘ฃ, ๐‘˜). Further, because ๐‘ฃ๐‘— is adjacent to ๐‘ฃ and ๐‘ข๐‘–๐‘— , so we can said that ๐‘Š๐‘™ is a dominant local resolving set of ๐‘Ž๐‘š๐‘Ž๐‘™(๐‘†๐‘›, ๐‘ฃ, ๐‘˜). Next, take any ๐‘† โŠ† ๐‘‰(๐‘Ž๐‘š๐‘Ž๐‘™(๐‘†๐‘›, ๐‘ฃ, ๐‘˜)) with |๐‘†| < |๐‘Š๐‘™ |. Without loss of generality, let |๐‘†| = |๐‘Š๐‘™ | โˆ’ 1 with ๐‘Š๐‘™ = {๐‘ฃ๐‘— |๐‘— = 1,2,3, โ€ฆ , ๐‘˜ โˆ’ 1}, so ๐‘ข๐‘–๐‘˜ are not adjacent to ๐‘†. So ๐‘† is not a dominant local resolving set of ๐‘Ž๐‘š๐‘Ž๐‘™(๐‘†๐‘›, ๐‘ฃ, ๐‘˜). Based on Lemma 1, any set ๐‘‡ with |๐‘‡| < |๐‘†| is not a dominant local resolving set of ๐บ. Therefore, ๐‘Š๐‘™ = {๐‘ฃ๐‘— } is a dominant local basis of ๐‘Ž๐‘š๐‘Ž๐‘™(๐‘†๐‘›, ๐‘ฃ, ๐‘˜). Then its is proven that ๐ท๐‘‘๐‘–๐‘š๐‘™ (๐‘Ž๐‘š๐‘Ž๐‘™(๐‘†๐‘›, ๐‘ฃ, ๐‘˜)) = ๐‘˜ for ๐‘ฃ is pendant vertex of star of ๐‘†๐‘›. โˆŽ Figure 3. ๐ท๐‘‘๐‘–๐‘š๐‘™ (๐‘Ž๐‘š๐‘Ž๐‘™(๐‘†4, ๐‘ฃ, 3)) = 1. Figure 4. ๐ท๐‘‘๐‘–๐‘š๐‘™ (๐‘Ž๐‘š๐‘Ž๐‘™(๐‘†6, ๐‘ฃ, 5)) = 5 On the Dominant Local Resolving Set of Vertex Amalgamation Graphs Reni Umilasari 603 Figure 3 gives the illustration of dominant local metric dimension of ๐‘Ž๐‘š๐‘Ž๐‘™(๐‘†๐‘›, ๐‘ฃ, ๐‘˜) for ๐‘ฃ is the center vertex of ๐‘†๐‘›. While in Figure 4, ๐‘ฃ is the pendant of Star. The next theorem, we will show the dominan local metric dimension of complete graph. Because the graphs are regular, then we can select any vertex of complete graph as the linkage vertex. Theorem 2. Let ๐‘Ž๐‘š๐‘Ž๐‘™(๐พ๐‘›, ๐‘ฃ, ๐‘) is a vertex amalgamation of complete graph with the order of complete graph is ๐‘› โ‰ฅ 3, then ๐ท๐‘‘๐‘–๐‘š๐‘™ (๐‘Ž๐‘š๐‘Ž๐‘™(๐พ๐‘›, ๐‘ฃ, ๐‘)) = ๐‘ ร— (๐ท๐‘‘๐‘–๐‘š๐‘™ (๐พ๐‘›) โˆ’ 1). Proof. Let ๐‘‰(๐‘Ž๐‘š๐‘Ž๐‘™(๐พ๐‘›, ๐‘ฃ, ๐‘)) = {๐‘ฃ, ๐‘ฃ๐‘–๐‘— |๐‘– = 1,2,3, โ€ฆ , ๐‘› โˆ’ 1, ๐‘— = 1,2,3, โ€ฆ , ๐‘} and the edge set of ๐‘Ž๐‘š๐‘Ž๐‘™(๐พ๐‘›, ๐‘ฃ, ๐‘) is ๐ธ(๐‘Ž๐‘š๐‘Ž๐‘™(๐พ๐‘›, ๐‘ฃ, ๐‘)) = {๐‘ฃ๐‘ฃ๐‘–๐‘— , ๐‘ฃ๐‘ฅ๐‘— ๐‘ฃ๐‘ฆ๐‘— |๐‘– = 1,2,3, โ€ฆ , ๐‘› โˆ’ 1, ๐‘— = 1,2,3, โ€ฆ , ๐‘, ๐‘ฃ๐‘ฅ ๐‘ฃ๐‘ฆ โˆˆ ๐ธ(๐พ๐‘›), ๐‘ฅ โ‰  ๐‘ฆ }. The ๐‘—-th copy of ๐พ๐‘› with ๐‘— = 1,2,3, โ€ฆ , ๐‘ is called (๐พ๐‘›)๐‘— . Let ๐ต be a local dominant basis of ๐พ๐‘›, ๐ต๐‘— is a local dominant basis of (๐พ๐‘›)๐‘— , so that for every ๐‘— = 1,2,3, โ€ฆ , ๐‘, |๐ต๐‘– | = |๐ต|. Select ๐‘Š๐‘™ = โ‹ƒ ๐ต๐‘— ๐‘š ๐‘—=1 , with ๐ต๐‘— = {๐‘ฃ๐‘–๐‘— |๐‘— = 1,2,3, โ€ฆ , ๐‘› โˆ’ 2} for every ๐‘— = 1,2,3, โ€ฆ , ๐‘, then |๐‘Š๐‘™ | = ๐‘(๐‘› โˆ’ 2). By Lemma 2 for every ๐‘ฃ๐‘–๐‘— , ๐‘ฃ๐‘˜๐‘™ โˆˆ ๐ต๐‘– then ๐‘Ÿ(๐‘ฃ๐‘–๐‘— |๐‘Š๐‘™ ) โ‰  ๐‘Ÿ(๐‘ฃ๐‘˜๐‘™ |๐‘Š๐‘™ ). Next, we take any two adjacent vertices in ๐‘‰(๐‘Ž๐‘š๐‘Ž๐‘™(๐พ๐‘›, ๐‘ฃ, ๐‘))\๐‘Š๐‘™ . Let ๐‘ฅ, ๐‘ฆ โˆˆ ๐‘‰(๐‘Ž๐‘š๐‘Ž๐‘™(๐พ๐‘›, ๐‘ฃ, ๐‘))\๐‘Š๐‘™ , then for ๐‘ฅ๐‘ฆ = ๐‘ฃ, ๐‘ฃ๐‘›๐‘— โˆˆ ๐‘‰(๐‘Ž๐‘š๐‘Ž๐‘™(๐พ๐‘›, ๐‘ฃ, ๐‘))\๐‘Š๐‘™ with ๐‘— = 1,2,3, โ€ฆ , ๐‘. Since ๐‘Ž๐‘š๐‘Ž๐‘™(๐พ๐‘›, ๐‘ฃ, ๐‘) is a connected graph, ๐‘‘(๐‘ฃ๐‘›๐‘— , ๐‘ง) = ๐‘‘(๐‘ฃ๐‘›๐‘— , ๐‘ฃ) + ๐‘‘(๐‘ฃ, ๐‘ง)for every ๐‘ง โˆˆ ๐ต๐‘– so that ๐‘‘(๐‘ง, ๐‘ฃ๐‘›๐‘— ) โ‰  ๐‘‘(๐‘ง, ๐‘ฃ) caused ๐‘Ÿ(๐‘ฃ๐‘›๐‘— |๐ต๐‘–) โ‰  ๐‘Ÿ(๐‘ฃ|๐ต๐‘–). Because of ๐ต๐‘– โŠ† ๐‘Š๐‘™ then ๐‘Ÿ(๐‘ฃ๐‘›๐‘— |๐‘Š๐‘™ ) โ‰  ๐‘Ÿ(๐‘ง|๐‘Š๐‘™ ). Based on the explanation above, ๐‘Š๐‘™ = โ‹ƒ ๐ต๐‘– ๐‘š ๐‘–=1 is a local resolving set of ๐‘Ž๐‘š๐‘Ž๐‘™(๐พ๐‘›, ๐‘ฃ, ๐‘). Since, every ๐‘ฃ๐‘–๐‘— โˆˆ ๐‘Š๐‘™ with ๐‘– = 1,2,3, โ€ฆ , ๐‘› โˆ’ 2 and ๐‘— = 1,2,3, โ€ฆ , ๐‘ is adjacent to ๐‘ฃ and ๐‘ฃ๐‘›๐‘— , then ๐‘Š๐‘™ is a dominating set. So that, ๐‘Š๐‘™ = โ‹ƒ ๐ต๐‘— ๐‘ ๐‘—=1 is a local dominant resolving set of ๐‘Ž๐‘š๐‘Ž๐‘™(๐พ๐‘›, ๐‘ฃ, ๐‘). Take any ๐‘† โŠ† ๐‘‰(๐บ) with |๐‘†| < |๐‘Š๐‘™ |. Let |๐‘†| = |๐‘Š๐‘™ | โˆ’ 1, then there exists ๐‘— such as ๐‘† contains maximal |๐ต๐‘— | โˆ’ 1 elements of (๐พ๐‘›)๐‘— . Since ๐ต๐‘— is a local dominant basis of (๐พ๐‘›)๐‘— then there exist two vertices in (๐พ๐‘›)๐‘— that have the same representation toward ๐‘†, so that ๐‘† is not a local dominant resolving set of ๐‘Ž๐‘š๐‘Ž๐‘™(๐พ๐‘›, ๐‘ฃ, ๐‘). Based on Lemma 1 then ๐‘Š๐‘™ = โ‹ƒ ๐ต๐‘— ๐‘ ๐‘—=1 is a local dominant basis of ๐‘Ž๐‘š๐‘Ž๐‘™(๐พ๐‘›, ๐‘ฃ, ๐‘). By Table 1 we know that |๐ต๐‘– | = ๐ท๐‘‘๐‘–๐‘š๐‘™ ((๐พ๐‘›)๐‘– ) โˆ’ 1, then it has been proven that ๐ท๐‘‘๐‘–๐‘š๐‘™ (๐‘Ž๐‘š๐‘Ž๐‘™(๐พ๐‘›, ๐‘ฃ, ๐‘)) = ๐‘ ร— (๐ท๐‘‘๐‘–๐‘š๐‘™ (๐พ๐‘›) โˆ’ 1). โˆŽ The example of dominant local metric dimension of vertex amalgamation complete graph be given in Figure 5. The graph show that ๐‘Ž๐‘š๐‘Ž๐‘™(๐พ4, ๐‘ฃ, 3) has the dominant local metric dimension equals six. Figure 5. ๐ท๐‘‘๐‘–๐‘š๐‘™ (๐‘Ž๐‘š๐‘Ž๐‘™(๐พ4, ๐‘ฃ, 3)) = 6. Theorem 3. Let ๐‘Ž๐‘š๐‘Ž๐‘™(๐พ๐‘š,๐‘›, ๐‘ฃ, ๐‘) is a vertex amalgamation of complete bipartite graph with the order is ๐‘š, ๐‘› โ‰ฅ 2, then ๐ท๐‘‘๐‘–๐‘š๐‘™ (๐‘Ž๐‘š๐‘Ž๐‘™(๐พ๐‘š,๐‘›, ๐‘ฃ, ๐‘)) = ๐‘ + 1. On the Dominant Local Resolving Set of Vertex Amalgamation Graphs Reni Umilasari 604 Proof. Let the vertex set of ๐พ๐‘š,๐‘› is ๐‘‰(๐พ๐‘š,๐‘›) = {๐‘Ž๐‘– |๐‘– = 1,2, โ€ฆ , ๐‘š} โˆช {๐‘๐‘— |๐‘— = 1,2, โ€ฆ , ๐‘›}, and the edge set is ๐ธ(๐พ๐‘š,๐‘›) = {๐‘Ž๐‘– ๐‘๐‘— |๐‘– = 1,2, โ€ฆ , ๐‘š; ๐‘— = 1,2, โ€ฆ , ๐‘›}. ๐‘‰ (๐‘Ž๐‘š๐‘Ž๐‘™(๐พ๐‘š,๐‘›, ๐‘ฃ, ๐‘)) = {๐‘ฃ, ๐‘Ž๐‘–๐‘˜ , ๐‘๐‘—๐‘˜ |๐‘– = 2,3, โ€ฆ , ๐‘š, ๐‘— = 1,2, โ€ฆ , ๐‘›, ๐‘˜ = 1,2, โ€ฆ , ๐‘} and the edge set is ๐ธ (๐‘Ž๐‘š๐‘Ž๐‘™(๐พ๐‘š,๐‘›, ๐‘ฃ, ๐‘)) = {๐‘ฃ๐‘๐‘—๐‘˜ , ๐‘Ž๐‘–๐‘˜ ๐‘๐‘—๐‘˜ |๐‘– = 2,3, โ€ฆ , ๐‘š, ๐‘— = 1,2, โ€ฆ , ๐‘›, ๐‘˜ = 1,2, โ€ฆ , ๐‘}. Choose, ๐‘Š๐‘™ = {๐‘ฃ, ๐‘1๐‘˜ } for every ๐‘˜ = 1,2,3, โ€ฆ , ๐‘, then |๐‘Š๐‘™ | = ๐‘ + 1. We can show below that the representation of every two adjacent vertices of๐‘‰ (๐‘Ž๐‘š๐‘Ž๐‘™(๐พ๐‘š,๐‘›, ๐‘ฃ, ๐‘)) is different. i. For ๐‘ฃ๐‘๐‘—๐‘˜ โˆˆ ๐ธ (๐‘Ž๐‘š๐‘Ž๐‘™(๐พ๐‘š,๐‘›, ๐‘ฃ, ๐‘)) Since ๐‘ฃ is element of ๐‘Š๐‘™ , then there exist 0 on 1 ๐‘ ๐‘ก element in ๐‘Ÿ(๐‘ฃ|๐‘Š๐‘™ ), while for ๐‘Ÿ(๐‘๐‘—๐‘˜ |๐‘Š๐‘™ ) there are no zero elements except ๐‘1๐‘˜ the representation to ๐‘Š๐‘™ is ๐‘Ÿ(๐‘1๐‘˜ |๐‘Š๐‘™ ) = (1,0), hence ๐‘Ÿ(๐‘ฃ|๐‘Š๐‘™ ) โ‰  ๐‘Ÿ(๐‘๐‘—๐‘˜ |๐‘Š๐‘™ ). ii. For ๐‘Ž๐‘–๐‘˜ ๐‘๐‘—๐‘˜ โˆˆ ๐ธ (๐‘Ž๐‘š๐‘Ž๐‘™(๐พ๐‘š,๐‘›, ๐‘ฃ, ๐‘)) Since for ๐‘– = 2,3, โ€ฆ , ๐‘š, ๐‘— = 1,2, โ€ฆ , ๐‘›, ๐‘‘(๐‘Ž๐‘–๐‘˜ , ๐‘ฃ) = ๐‘‘(๐‘Ž๐‘–๐‘˜ , ๐‘๐‘—๐‘˜ ) + ๐‘‘(๐‘๐‘—๐‘˜ , ๐‘ฃ) hence ๐‘Ÿ(๐‘Ž๐‘–๐‘˜|๐‘Š๐‘™ ) โ‰  ๐‘Ÿ(๐‘๐‘—๐‘˜ |๐‘Š๐‘™ ). From the two explanations above we know that ๐‘Š๐‘™ is the local resolving set of ๐‘Ž๐‘š๐‘Ž๐‘™(๐พ๐‘š,๐‘›, ๐‘ฃ, ๐‘). Since ๐‘ฃ is adjacent to ๐‘๐‘—๐‘˜ for ๐‘— = 1,2, โ€ฆ , ๐‘› and ๐‘˜ = 1,2, โ€ฆ , ๐‘. The vertex ๐‘1๐‘˜ is adjacent to ๐‘Ž๐‘–๐‘˜ for ๐‘– = 2,3, โ€ฆ , ๐‘š and ๐‘˜ = 1,2, โ€ฆ , ๐‘, thus ๐‘Š๐‘™ is dominant local resolving set of ๐‘Ž๐‘š๐‘Ž๐‘™(๐พ๐‘š,๐‘›, ๐‘ฃ, ๐‘). Take any ๐‘† โŠ† ๐‘‰(๐บ) with |๐‘†| < |๐‘Š๐‘™ |. Let |๐‘†| = |๐‘Š๐‘™ | โˆ’ 1 the two possibilities below: a. If ๐‘ฃ โˆ‰ ๐‘Š๐‘™ ๐‘ฃ โˆ‰ ๐‘Š๐‘™ , then all vertices ๐‘๐‘—๐‘˜ with ๐‘— = 2,3, โ€ฆ , ๐‘› and ๐‘˜ = 1,2, โ€ฆ , ๐‘ cannot be dominated by ๐‘Š๐‘™ . b. If ๐‘ฃ โˆˆ ๐‘Š๐‘™ ๐‘ฃ โˆˆ ๐‘Š๐‘™ , then there exist ๐‘1๐‘˜ โˆ‰ ๐‘Š๐‘™ for ๐‘˜ = 1,2, โ€ฆ , ๐‘. Without loss of generality suppose that ๐‘11 โˆ‰ ๐‘Š๐‘™ . It means that ๐‘Ž๐‘–1 cannot be dominated by ๐‘Š๐‘™ for ๐‘– = 2,3, โ€ฆ , ๐‘š. Therefore, from two possibilities above ๐‘† is not a local dominant resolving set of ๐‘Ž๐‘š๐‘Ž๐‘™(๐พ๐‘š,๐‘›, ๐‘ฃ, ๐‘) or we can conclude that ๐‘Š๐‘™ = ๐‘ + 1 is dominant local basis of ๐‘Ž๐‘š๐‘Ž๐‘™(๐พ๐‘š,๐‘›, ๐‘ฃ, ๐‘). Hence, we get ๐ท๐‘‘๐‘–๐‘š๐‘™ (๐‘Ž๐‘š๐‘Ž๐‘™(๐พ๐‘š,๐‘›, ๐‘ฃ, ๐‘)) = ๐‘ + 1. โˆŽ The example of a dominant local basis for vertex amalgamation of a complete bipartite graph is depicted as red vertices in Figure 5, where ๐ท๐‘‘๐‘–๐‘š๐‘™ (๐‘Ž๐‘š๐‘Ž๐‘™(๐พ3,3, ๐‘ฃ, 3)) = 4. Figure 6. ๐ท๐‘‘๐‘–๐‘š๐‘™ (๐‘Ž๐‘š๐‘Ž๐‘™(๐พ3,3, ๐‘ฃ, 3)) = 4. On the Dominant Local Resolving Set of Vertex Amalgamation Graphs Reni Umilasari 605 Theorem 4. Let ๐‘Ž๐‘š๐‘Ž๐‘™(๐น๐‘›, ๐‘ฃ, ๐‘) is a vertex amalgamation of friendship graph with the order is ๐‘› โ‰ฅ 3 then ๐ท๐‘‘๐‘–๐‘š๐‘™ (๐‘Ž๐‘š๐‘Ž๐‘™(๐น๐‘›, ๐‘ฃ, ๐‘)) = { ๐ท๐‘‘๐‘–๐‘š๐‘™ (๐น๐‘›), ๐‘ฃ ๐‘–๐‘  ๐‘Ž ๐‘๐‘’๐‘›๐‘ก๐‘’๐‘Ÿ ๐‘ฃ๐‘’๐‘Ÿ๐‘ก๐‘’๐‘ฅ ๐‘œ๐‘“ ๐น๐‘› 1 + ๐‘(๐ท๐‘‘๐‘–๐‘š๐‘™ (๐น๐‘›) โˆ’ 1), ๐‘ฃ ๐‘–๐‘  ๐‘›๐‘œ๐‘ก ๐‘Ž ๐‘๐‘’๐‘›๐‘ก๐‘’๐‘Ÿ ๐‘ฃ๐‘’๐‘Ÿ๐‘ก๐‘’๐‘ฅ ๐‘œ๐‘“ ๐น๐‘› Proof. Case 1. ๐‘ฃ is a center vertex of ๐น๐‘› It is very clearly to see that ๐‘Ž๐‘š๐‘Ž๐‘™(๐น๐‘›, ๐‘ฃ, ๐‘) โ‰… ๐น๐‘› , then by the Table 1 we can conclude that ๐ท๐‘‘๐‘–๐‘š๐‘™ (๐‘Ž๐‘š๐‘Ž๐‘™(๐น๐‘› , ๐‘ฃ, ๐‘)) = ๐ท๐‘‘๐‘–๐‘š๐‘™ (๐น๐‘›). โˆŽ Case 2. ๐‘ฃ is not a center vertex of ๐น๐‘› Let ๐‘‰(๐‘Ž๐‘š๐‘Ž๐‘™(๐น๐‘›, ๐‘ฃ, ๐‘)) = {๐‘ฃ, ๐‘ฃ๐‘– , ๐‘ฅ๐‘–๐‘˜ , ๐‘ฆ๐‘–๐‘— |๐‘– = 1,2,3, โ€ฆ , ๐‘; ๐‘— = 1,2,3, โ€ฆ , ๐‘›; ๐‘˜ = 2,3,4, โ€ฆ , ๐‘›} and ๐ธ(๐‘Ž๐‘š๐‘Ž๐‘™(๐น๐‘› , ๐‘ฃ, ๐‘)) = {๐‘ฃ๐‘– ๐‘ฅ๐‘–๐‘˜ , ๐‘ฃ๐‘– ๐‘ฆ๐‘–๐‘— , ๐‘ฅ๐‘–๐‘˜ ๐‘ฆ๐‘–๐‘— , ๐‘ฃ๐‘ฆ๐‘–1|๐‘– = 1,2, โ€ฆ , ๐‘; ๐‘— = 1,2, โ€ฆ , ๐‘›; ๐‘˜ = 2,3,4, โ€ฆ , ๐‘› }. The ๐‘–-th copy of ๐น๐‘› with ๐‘– = 1,2,3, โ€ฆ , ๐‘ is called (๐น๐‘›)๐‘– . Let ๐ต be a local dominant basis of ๐น๐‘› , ๐ต๐‘– is a local dominant basis of (๐น๐‘› )๐‘–, so that for every ๐‘– = 1,2,3, โ€ฆ , ๐‘, |๐ต๐‘– | = |๐ต| = ๐‘›. Select ๐‘Š๐‘™ = {๐‘ฃ} โ‹ƒ (๐ต๐‘– โˆ’ 1) ๐‘ ๐‘–=1 , suppose ๐ต๐‘– โˆ’ 1 = {๐‘ฅ๐‘–๐‘˜ |๐‘˜ = 2,3, โ€ฆ , ๐‘›} for every ๐‘– = 1,2,3, โ€ฆ , ๐‘, then |๐‘Š๐‘™ | = 1 + ๐‘(๐‘› โˆ’ 1). By Lemma 2 for every ๐‘ฅ๐‘Ž๐‘ , ๐‘ฅ๐‘๐‘‘ โˆˆ ๐ต๐‘– then ๐‘Ÿ(๐‘ฅ๐‘Ž๐‘ |๐‘Š๐‘™ ) โ‰  ๐‘Ÿ(๐‘ฅ๐‘๐‘‘ |๐‘Š๐‘™ ). Next, we take any two adjacent vertices in ๐‘‰(๐บ)\๐‘Š๐‘™. Let ๐‘ฃ๐‘– , ๐‘ฆ๐‘–๐‘— โˆˆ ๐‘‰(๐บ)\๐‘Š๐‘™ with ๐‘– = 1,2,3, โ€ฆ , ๐‘ and ๐‘— = 2,3, โ€ฆ , ๐‘›. Since ๐‘Ž๐‘š๐‘Ž๐‘™(๐น๐‘›, ๐‘ฃ, ๐‘) is a connected graph, for ๐‘‘(๐‘ฆ๐‘–๐‘— , ๐‘ฃ) = ๐‘‘(๐‘ฆ๐‘–๐‘— , ๐‘ฃ๐‘– ) + ๐‘‘(๐‘ฃ๐‘– , ๐‘ฃ) for ๐‘— โ‰  1, ๐‘ฃ โˆˆ ๐‘Š๐‘™ so that ๐‘‘(๐‘ฃ, ๐‘ฆ๐‘–๐‘— ) โ‰  ๐‘‘(๐‘ฃ, ๐‘ฃ๐‘– ) caused ๐‘Ÿ(๐‘ฆ๐‘–๐‘— |๐‘Š๐‘™ ) โ‰  ๐‘Ÿ(๐‘ฃ๐‘– |๐‘Š๐‘™ ). Then, ๐‘Š๐‘™ is local resolving set of ๐‘Ž๐‘š๐‘Ž๐‘™(๐น๐‘›, ๐‘ฃ, ๐‘). Moreover, since ๐‘ฃ adjacent to ๐‘ฃ๐‘– and ๐‘ฅ๐‘–๐‘˜ adjacent to ๐‘ฆ๐‘–๐‘— , hence ๐‘Š๐‘™ is dominant local resolving set of ๐‘Ž๐‘š๐‘Ž๐‘™(๐น๐‘› , ๐‘ฃ, ๐‘). Take any ๐‘† โŠ† ๐‘‰(๐‘Ž๐‘š๐‘Ž๐‘™(๐น๐‘›, ๐‘ฃ, ๐‘)) with |๐‘†| < |๐‘Š๐‘™ |. Let |๐‘†| = |๐‘Š๐‘™ | โˆ’ 1 the two possibilities below. a) If ๐‘ฃ โˆ‰ ๐‘Š๐‘™ ๐‘ฃ โˆ‰ ๐‘Š๐‘™ , then all vertices ๐‘ฆ๐‘–1 with ๐‘– = 1,2, โ€ฆ , ๐‘ cannot be dominated by ๐‘Š๐‘™ . b) If ๐‘ฃ โˆˆ ๐‘Š๐‘™ ๐‘ฃ โˆˆ ๐‘Š๐‘™ , then there exist ๐‘ฅ๐‘–๐‘˜ โˆ‰ ๐‘Š๐‘™ for ๐‘˜ = 2,3 โ€ฆ , ๐‘›. Without loss of generality suppose that ๐‘ฅ1๐‘› โˆ‰ ๐‘Š๐‘™ . It means that ๐‘ฆ1๐‘› cannot be dominated by ๐‘Š๐‘™ . Therefore, from two possibilities above ๐‘† is not a local dominant resolving set of ๐‘Ž๐‘š๐‘Ž๐‘™(๐น๐‘›, ๐‘ฃ, ๐‘) or we can conclude that |๐‘Š๐‘™ | = 1 + ๐‘(๐‘› โˆ’ 1) is dominant local basis of ๐‘Ž๐‘š๐‘Ž๐‘™(๐น๐‘›, ๐‘ฃ, ๐‘). Hence, we get ๐ท๐‘‘๐‘–๐‘š๐‘™ (๐‘Ž๐‘š๐‘Ž๐‘™(๐น๐‘› , ๐‘ฃ, ๐‘)) = 1 + ๐‘(๐ท๐‘‘๐‘–๐‘š๐‘™ (๐น๐‘›) โˆ’ 1) . โˆŽ Figure 6 gives an axample of ๐‘Ž๐‘š๐‘Ž๐‘™(๐น3, ๐‘ฃ, 3), where ๐‘ฃ is not the center vertex of friendship. Those graph has dominant local resolving set equals seven. Figure 7. ๐ท๐‘‘๐‘–๐‘š๐‘™ (๐น3, ๐‘ฃ, 3) = 7 On the Dominant Local Resolving Set of Vertex Amalgamation Graphs Reni Umilasari 606 CONCLUSION Based on the findings of this study, it is possible to conclude that the dominant local metric dimension for any vertex amalgamation product graph is determined by the dominant local metric dimension of the copied graphs and how the terminal vertex is chosen. This topic can be expanded by observing the dominant local metric dimension for the vertex amalgamation product with the special graphs that will be glued are different graphs. Next, we can determined the dominant local metric dimension for another product of graphs. 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