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All Journal Electronic Journal of Graph Theory and Applications (EJGTA) Journal of Mathematical and Fundamental Sciences Science and Technology Indonesia
Saladin Uttunggadewa
Institut Teknologi Bandung
Astronomy Biochemistry, Genetics & Molecular Biology Chemical Engineering, Chemistry & Bioengineering Chemistry Earth & Planetary Sciences Electrical & Electronics Engineering Environmental Science Materials Science & Nanotechnology Mathematics Physics

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Restricted size Ramsey number for path of order three versus graph of order five Denny Riama Silaban; Edy Tri Baskoro; Saladin Uttunggadewa
Electronic Journal of Graph Theory and Applications (EJGTA) Vol 5, No 1 (2017): Electronic Journal of Graph Theory and Applications
Publisher : GTA Research Group, Univ. Newcastle, Indonesian Combinatorics Society and ITB

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/ejgta.2017.5.1.15

Abstract

Let $G$ and $H$ be simple graphs. The Ramsey number for a pair of graph $G$ and $H$ is the smallest number $r$ such that any red-blue coloring of edges of $K_r$ contains a red subgraph $G$ or a blue subgraph $H$. The size Ramsey number for a pair of graph $G$ and $H$ is the smallest number $\hat{r}$ such that there exists a graph $F$ with size $\hat{r}$ satisfying the property that any red-blue coloring of edges of $F$ contains a red subgraph $G$ or a blue subgraph $H$. Additionally, if the order of $F$ in the size Ramsey number is $r(G,H)$, then it is called the restricted size Ramsey number. In 1983, Harary and Miller started to find the (restricted) size Ramsey number for any pair of small graphs with order at most four. Faudree and Sheehan (1983) continued Harary and Miller's works and summarized the complete results on the (restricted) size Ramsey number for any pair of small graphs with order at most four. In 1998, Lortz and Mengenser gave both the size Ramsey number and the restricted size Ramsey number for any pair of small forests with order at most five. To continue their works, we investigate the restricted size Ramsey number for a path of order three versus connected graph of order five.
On the restricted size Ramsey number for P3 versus dense connected graphs Denny Riama Silaban; Edy Tri Baskoro; Saladin Uttunggadewa
Electronic Journal of Graph Theory and Applications (EJGTA) Vol 8, No 2 (2020): Electronic Journal of Graph Theory and Applications
Publisher : GTA Research Group, Univ. Newcastle, Indonesian Combinatorics Society and ITB

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/ejgta.2020.8.2.14

Abstract

Let F, G and H be simple graphs. A graph F is said a (G,H)-arrowing graph if in any red-blue coloring of edges of F we can find a red G or a blue H. The size Ramsey number of G and H, ŕ(G,H), is the minimum size of F. If the order of F equals to the Ramsey number of G and H, r(G,H), then the minimum size of F is called the restricted size Ramsey number of G and H, r*(G,H). The Ramsey number of G and H, r(G,H), is the minimum order of F. In this paper, we study the restricted size number involving a P3.  The value of r*(P3,Kn) has been given by Faudree and Sheehan. Here, we examine r*(P3,H) where H is dense connected graph.
Optimization Model for an Airline Crew Rostering Problem: Case of Garuda Indonesia Rieske Hadianti; Khusnul Novianingsih; Saladin Uttunggadewa; Kuntjoro A. Sidarto; Novriana Sumarti; Edy Soewono
Journal of Mathematical and Fundamental Sciences Vol. 45 No. 3 (2013)
Publisher : Institute for Research and Community Services (LPPM) ITB

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/j.math.fund.sci.2013.45.3.2

Abstract

This paper discusses the cockpit crew rostering problem at Garuda Indonesia, taking into account a number of internal cockpit crew labor regulations. These internal labor regulations are in general more restrictive at Garuda Indonesia than at other airlines, so that modeling the cockpit crew rostering problem for Garuda Indonesia is challenging. We have derived mathematical expressions for the cockpit crew labor regulations and some technical matters. We model a non-linear integer programming for the rostering problem, using the average relative deviation of total flight time to the ideal flight time as the objective function. The optimization model have been tested for all classes of cockpit crews of Garuda Indonesia, using a simulated annealing method for solving the problem. We obtained satisfactory rosters for all crew members in a short amount of computing time. This shows that the optimization problem is well-defined.
Restricted Size Ramsey Number Involving Matching and Graph of Order Five Denny Riama Silaban; Edy Tri Baskoro; Saladin Uttunggadewa
Journal of Mathematical and Fundamental Sciences Vol. 52 No. 2 (2020)
Publisher : Institute for Research and Community Services (LPPM) ITB

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/j.math.fund.sci.2020.52.2.1

Abstract

Harary and Miller (1983) started the research on the (restricted) size Ramsey number for a pair of small graphs. They obtained the values for some pairs of small graphs with order not more than four. In the same year, Faudree and Sheehan continued the research and extended the result to all pairs of small graphs with order not more than four. Moreover, in 1998, Lortz and Mengenser gave the size Ramsey number and the restricted size Ramsey number for all pairs of small forests with order not more than five. Recently, we gave the restricted size Ramsey number for a path of order three and any connected graph of order five. In this paper, we continue the research on the (restricted) size Ramsey number involving small graphs by investigating the restricted size Ramsey number for matching with two edges versus any graph of order five with no isolates.
Uncovering Obstacles to Household Waste Recycling in Seremban, Malaysia through Decision-Making Trial and Evaluation Laboratory (DEMATEL) Analysis. Zahari Md Rodzi; Ashiera Nadiha Hazri; Nurul Ain Syahirah Mohd Azri; Nurul Dania Farisha Sharul Rhmdan; Zati Aqmar Zaharudin; Saladin Uttunggadewa
Science and Technology Indonesia Vol. 8 No. 3 (2023): July
Publisher : Research Center of Inorganic Materials and Coordination Complexes, FMIPA Universitas Sriwijaya

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.26554/sti.2023.8.3.422-428

Abstract

This study investigates the barriers to household waste recycling in Seremban, Malaysia, using the Decision-Making Trial and Evaluation Laboratory (DEMATEL) analysis. The research questions aimed to identify and rank the most significant barriers to recycling and understand the causal relationships between them. The study found that limited access to recycling facilities and services and lack of motivation or incentive to recycle were the most significant causes of household waste recycling barriers in Seremban. Onthe other hand, lack of motivation or incentive to recycle and negative attitudes towards recycling, were identified as the most significant effects. The study’s findings have theoretical implications for waste management and sustainable development and offer practical implications for policymakers and waste management practitioners in developing effective waste management strategies and policies that can address these barriers. Furthermore, the study’s insights into the most significant barriers to household waste recycling can inform the design of recycling campaigns and educational programs to increase awareness and promote household waste recycling in Seremban. Overall, this study provides a valuable contribution to the field of waste management and sustainable development and offers insights into the challenges of promoting household waste recycling in urban areas.
Magic labeling on graphs with ascending subgraph decomposition Pancahayani, Sigit; Simanjuntak, Rinovia; Uttunggadewa, Saladin
Electronic Journal of Graph Theory and Applications (EJGTA) Vol 12, No 2 (2024): Electronic Journal of Graph Theory and Applications
Publisher : GTA Research Group, Univ. Newcastle, Indonesian Combinatorics Society and ITB

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/ejgta.2024.12.2.4

Abstract

Let t and q be positive integers that satisfy C(t + 1,2) ≤ q < C(t + 2,2) and let G be a simple and finite graph of size q. G is said to have ascending subgraph decomposition (ASD) if G can be decomposed into t subgraphs H1,H2,…,Ht without isolated vertices such that Hi is isomorphic to a proper subgraph of Hi+1 for 1 ≤ i ≤ t - 1, where {E(H1),…,E(Ht)} is a partition of E(G). A graph that admits an ascending subgraph decomposition is called an ASD graph.In this paper, we introduce a new type of magic labeling based on the notion of ASD. Let G be an ASD graph and f : V (G) ∪E(G) →{1,2,…,|V (G)| + |E(G)|} be a bijection. The weight of a subgraph Hi (1 ≤ i ≤ n) is w(Hi) = ∑ v∈V (Hi)f(v) + ∑ e∈E(Hi)f(e). If the weight of each ascending subgraph is constant, say w(Hi) = k, ∀ 1 ≤ i ≤ t, then f is called an ASD-magic labeling of G and G is called an ASD-magic graph. We present general properties of ASD-magic graphs and characterize certain classes of them.
On the relations among edge magic total, edge antimagic total, and ASD-antimagic graphs Pancahayani, Sigit; Simanjuntak, Rinovia; Baca, Martin; Semanicova-Fenovcıkova, Andrea; Uttunggadewa, Saladin
Electronic Journal of Graph Theory and Applications (EJGTA) Vol 13, No 2 (2025): Electronic Journal of Graph Theory and Applications
Publisher : GTA Research Group, Univ. Newcastle, Indonesian Combinatorics Society and ITB

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.5614/ejgta.2025.13.2.11

Abstract

Let G be a simple and finite graph of order p and size q. The graph G is said to be edge magic total (EMT) if there is a bijection λ:V(G)∪E(G)→{1,2,…,p+q} such that all edge sums λ(x)+λ(xy)+λ(y), xy∈E(G), are the same. If all edge sums are pairwise distinct, then G is called edge antimagic total (EAT). Let t be a positive integer that satisfies C(t+1,2)≤q<C(t+2,2). The graph G is said to have an ascending subgraph decomposition (ASD) if G can be decomposed into t subgraphs H1,H2,…,Ht without isolated vertices such that Hi is isomorphic to a proper subgraph of Hi+1 for 1≤i≤t−1. A graph that admits an ascending subgraph decomposition is called an ASD graph. An ASD graph G is said to be ASD-antimagic if there exists a bijection f:V(G)∪E(G)→{1,2,…,p+q} such that all subgraph weights w(Hi)=∑v∈V(Hi)f(v)+∑e∈E(Hi)f(e), 1≤i≤t, are distinct. In this paper, we provide constructions of ASD-antimagic graphs arising from EMT or EAT graphs.
Co-Authors Ashiera Nadiha Hazri Baca, Martin Denny Riama Silaban Denny Riama Silaban Edy Soewono Edy Tri Baskoro Khusnul Novianingsih Kuntjoro A. Sidarto Novriana Sumarti Nurul Ain Syahirah Mohd Azri Nurul Dania Farisha Sharul Rhmdan Pancahayani, Sigit Pancahayani, Sigit Rieske Hadianti Semanicova-Fenovcıkova, Andrea Simanjuntak, Rinovia Simanjuntak, Rinovia Zahari Md Rodzi Zati Aqmar Zaharudin