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INDONESIA
Indonesian Journal of Combinatorics
ISSN : 25412205     EISSN : -     DOI : -
Core Subject : Science,
Indonesian Journal of Combinatorics (IJC) publishes current research articles in any area of combinatorics and graph theory such as graph labelings, optimal network problems, metric dimension, graph coloring, rainbow connection and other related topics. IJC is published by the Indonesian Combinatorial Society (InaCombS), CGANT Research Group Universitas Jember (UNEJ), and Department of Mathematics Universitas Indonesia (UI).
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Articles 5 Documents
Search results for , issue "Vol 8, No 1 (2024)" : 5 Documents clear
Numbers of Weights of Convex Quadrilaterals in Weighted Point Sets Sakai, Toshinori; Matsumoto, Satoshi
Indonesian Journal of Combinatorics Vol 8, No 1 (2024)
Publisher : Indonesian Combinatorial Society (InaCombS)

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.19184/ijc.2024.8.1.1

Abstract

Let ℘n denote the family of sets of points in general position in the plane each of which is assigned a different number, called a weight, in {1,2,...,n}. For P∈℘n and a polygon Q with vertices in P, we define the weight of Q as the sum of the weights of its vertices and denote by Wk(P) the set of weights of convex k-gons with vertices in P∈℘n. Let fk(n) = minP∈℘n |Wk(P)|. It is known that n-5 ≤ f4(n) ≤ 2n-9 for n≥7. In this paper, we show that f4(n)≥ 4n/3-7.
On the generating graph of a finite group Mohammed Salih, Haval M.
Indonesian Journal of Combinatorics Vol 8, No 1 (2024)
Publisher : Indonesian Combinatorial Society (InaCombS)

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.19184/ijc.2024.8.1.3

Abstract

In this paper, we study the generating graph for some finite groups which are semi-direct product ℤn ⋊ ℤm (direct product ℤn × ℤm) of cyclic groups ℤn and ℤm. We show that the generating graphs of them are regular (bi-regular, tri-regular) connected graph with diameter 2 and girth 3 if n and m are prime numbers. Several graph properties are obtained. Furthermore, the probability that 2-randomly elements that generate a finite group G is P(G) = |{(a,b) ∈ G×G|G=❬a,b❭}|/|G|2. We find the general formula for P(G) of given groups. Our computations are done with the aid of GAP and the YAGs package.
When is the maximal graph of a non-quasi-local atomic domain connected? Visweswaran, Subramanian
Indonesian Journal of Combinatorics Vol 8, No 1 (2024)
Publisher : Indonesian Combinatorial Society (InaCombS)

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.19184/ijc.2024.8.1.4

Abstract

In this paper, with any atomic domain R which admits at least two maximal ideals, we associate an undirected graph denoted by ???(R) whose vertex set is I(R)={Rπ | π∈ Irr(R)\J(R)} (where Irr(R) is the set of all irreducible elements of R and J(R) is the Jacobson radical of R) and distinct Rπ, Rπ' ∈ I(R) are adjacent if and only if Rπ + Rπ' ⊆ M for some maximal ideal M of R. We call ???(R) as the maximal graph of R. We denote the set of all maximal ideals of R by Max(R). In this paper, some necessary (respectively, sufficient) conditions on Max(R) are provided such that ???(R) is connected. Also, in this paper, in some cases, a necessary and sufficient condition is determined so that ???(R) is connected.
Local inclusive distance antimagic coloring of graphs Hadiputra, Fawwaz Fakhrurrozi; Farhan, Mohammad; Mukayis, Mukayis; Saputro, Suhadi Wido; Maryati, Tita Khalis
Indonesian Journal of Combinatorics Vol 8, No 1 (2024)
Publisher : Indonesian Combinatorial Society (InaCombS)

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.19184/ijc.2024.8.1.5

Abstract

For a simple graph G, a bijection f : V(G) → [1,|V (G)|] is called as a local inclusive distance antimagic (LIDA) labeling of G if w(u) ≠ w(v) for every two adjacent vertices u,v ∈ V(G) with w(u) = ∑x∈N [u] f(x). A graph G is said to be local inclusive distance antimagic (LIDA) graph if it admits a LIDA labeling. The function w induced by f also can be seen as a proper vertex coloring of G. The local inclusive distance antimagic (LIDA) chromatic number of G, denoted by χlida(G), is the minimum number of colors taken over all proper vertex colorings induced by LIDA labelings of G. In this paper, we study a LIDA labeling of simple graph. We provide some basic properties of LIDA labeling for any simple graphs. The LIDA chromatic number of certain multipartite graphs, double stars, subdivision of graphs and join product of graphs with K1 are also investigated. We present an upper bound for graphs obtained from subdivision of super edge-magic total graphs. Furthermore, we present some new open problems.
On Ramsey numbers for trees versus fans of even order Sherlin, Intan; Saputro, Suhadi Wido; Baskoro, Edy Tri; Oktariani, Finny
Indonesian Journal of Combinatorics Vol 8, No 1 (2024)
Publisher : Indonesian Combinatorial Society (InaCombS)

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.19184/ijc.2024.8.1.2

Abstract

Given two graphs G and H. The graph Ramsey number R(G, H) is the least natural number r such that for every graph F on r vertices, either F contains a copy of G or F̅ contains a copy of H. A vertex v is called a dominating vertex in a graph G if it is adjacent to all other vertices of G. A wheel Wm is a graph consisting one dominating vertex and m other vertices forming a cycle. A fan graph F1,m is a graph formed from a wheel Wm by removing one cycle-edge. In this paper, we consider the graph Ramsey number R(Tn,F1,m) of a tree Tn versus a fan F1,m. The study of R(Tn,F1,m) has been initiated by Li et. al. (2016) where Tn is a star, and continued by Sherlin et. al. (2023) for Tn which is not a star and fan F1,m with even m ≤ 8. This paper will give the graph Ramsey numbers R(Tn,F1,m) for odd m ≤ 8.

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