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Electronic Journal of Graph Theory and Applications (EJGTA)
ISSN : 23382287     EISSN : -     DOI : -
Core Subject : Engineering,
The Electronic Journal of Graph Theory and Applications (EJGTA) is a refereed journal devoted to all areas of modern graph theory together with applications to other fields of mathematics, computer science and other sciences. The journal is published by the Indonesian Combinatorial Society (InaCombS), Graph Theory and Applications (GTA) Research Group - The University of Newcastle - Australia, and Faculty of Mathematics and Natural Sciences - Institut Teknologi Bandung (ITB) Indonesia. Subscription to EJGTA is free. Full-text access to all papers is available for free. All research articles as well as surveys and articles of more general interest are welcome. All papers will be refereed in the normal manner of mathematical journals to maintain the highest standards. This journal is sponsored by CARMA (Computer-Assisted Research Mathematics and its Applications) Priority Research Centre - The University of Newcastle - Australia, and Study Program of Information System- University of Jember - Indonesia.
Arjuna Subject : -
Articles 382 Documents
Lower and upper bounds on independent double Roman domination in trees M. Kheibari; Hossein Abdollahzadeh Ahangar; R. Khoeilar; S.M. Sheikholeslami
Electronic Journal of Graph Theory and Applications (EJGTA) Vol 10, No 2 (2022): 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.2022.10.2.8

Abstract

For a graph G = (V, E), a double Roman dominating function (DRDF) f : V → {0, 1, 2, 3} has the property that for every vertex v ∈ V with f(v)=0, either there exists a neighbor u ∈ N(v), with f(u)=3, or at least two neighbors x, y ∈ N(v) having f(x)=f(y)=2, and every vertex with value 1 under f has at least a neighbor with value 2 or 3. The weight of a DRDF is the sum f(V)=∑v ∈ Vf(v). A DRDF f is an independent double Roman dominating function (IDRDF) if the vertices with weight at least two form an independent set. The independent double Roman domination number idR(G) is the minimum weight of an IDRDF on G. In this paper, we show that for every tree T with diameter at least three, i(T)+iR(T)−(s(T))/2 + 1 ≤ idR(T)≤i(T)+iR(T)+s(T)−2, where i(T),iR(T) and s(T) are the independent domination number, the independent Roman domination number and the number of support vertex of T, respectively.
Perfect matching transitivity of circulant graphs. Isaac Armando Reiter; Ju Zhou
Electronic Journal of Graph Theory and Applications (EJGTA) Vol 10, No 2 (2022): 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.2022.10.2.14

Abstract

A graph G is perfect matching transitive, shortly PM-transitive, if for any two perfect matchings M1 and M2 of G, there is an automorphism f : V(G)↦V(G) such that fe(M1)=M2, where fe(uv)=f(u)f(v). In this paper, the authors completely characterize the perfect matching transitivity of circulant graphs of order less than or equal to 10.
The sandpile group of a thick cycle graph Diane Christine Alar; Jonathan Celaya; Luis David Garcia Puente; Micah Henson; Ashley K. Wheeler
Electronic Journal of Graph Theory and Applications (EJGTA) Vol 10, No 2 (2022): 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.2022.10.2.20

Abstract

The majority of graphs whose sandpile groups are known are either regular or simple. We give an explicit formula for a family of non-regular multi-graphs called thick cycles. A thick cycle graph is a cycle where multi-edges are permitted. Its sandpile group is the direct sum of cyclic groups of orders given by quotients of greatest common divisors of minors of its Laplacian matrix. We show these greatest common divisors can be expressed in terms of monomials in the graph’s edge multiplicities.
Making graphs solvable in peg solitaire Jan-Hendrik de Wiljes; Martin Kreh
Electronic Journal of Graph Theory and Applications (EJGTA) Vol 10, No 2 (2022): 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.2022.10.2.3

Abstract

In 2011, Beeler and Hoilman generalized the game of peg solitaire to arbitrary connected graphs. Since then peg solitaire has been considered on quite a few classes of graphs. Beeler and Gray introduced the natural idea of adding edges to make an unsolvable graph solvable. Recently, the graph invariant ms(G), which is the minimal number of additional edges needed to make G solvable, has been introduced and investigated on banana trees by the authors. In this article, we determine ms(G) for several families of unsolvable graphs. Furthermore, we provide some general results for this number of Hamiltonian graphs and graphs obtained via binary graph operations.
Rainbow connection number of comb product of graphs Dinny Fitriani; ANM Salman; Zata Yumni Awanis
Electronic Journal of Graph Theory and Applications (EJGTA) Vol 10, No 2 (2022): 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.2022.10.2.9

Abstract

An edge-colored graph G is called a rainbow connected if any two vertices are connected by a path whose edges have distinct colors. Such a path is called a rainbow path. The smallest number of colors required in order to make G rainbow connected is called the rainbow connection number of G. For two connected graphs G and H with v ∈ V(H), the comb product between G and H, denoted by G⊳vH, is a graph obtained by taking one copy of G and |V(G)| copies of H and identifying the i-th copy of H at the vertex v to the i-th vertex of G. In this paper, we give sharp lower and upper bounds for the rainbow connection number of comb product between two connected graphs. We also determine the exact values of rainbow connection number of G⊳vH for some connected graphs G and H.
On b-edge consecutive edge magic total labeling on trees Eunike Setiawan; Kiki Ariyanti Sugeng; Denny Riama Silaban
Electronic Journal of Graph Theory and Applications (EJGTA) Vol 10, No 2 (2022): 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.2022.10.2.15

Abstract

Let G = (V, E) be a simple, connected, and undirected graph, where V and E are the set of vertices and the set of edges of G. An edge magic total labeling on G is a bijection f : V ∪ E → {1, 2, …, |V|+|E|}, provided that for every uv ∈ E, w(uv)=f(u)+f(v)+f(uv)=K for a constant number K. Such a labeling is said to be a super edge magic total labeling if f(V)={1,2,…,|V|} and a b-edge consecutive edge magic total labeling if f(E)={b+1,b+2,…,b+|E|} with b ≥ 1. In this research, we give sufficient conditions for a graph G having a super edge magic total labeling to have a b-edge consecutive edge magic total labeling. We also give several classes of connected graphs which have both labelings.
Multipartite Ramsey numbers for the union of stars I Wayan Palton Anuwiksa; Rinovia Simanjuntak; Edy Tri Baskoro
Electronic Journal of Graph Theory and Applications (EJGTA) Vol 10, No 2 (2022): 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.2022.10.2.21

Abstract

Let s and k be positive integers with k ≥ 2 and G1, G2, …, Gk be simple graphs. The set multipartite Ramsey number, denoted by Ms(G1, G2, …, Gk), is the smallest positive integer c such that any k-coloring of the edges of Kc × s contains a monochromatic copy of Gi in color i for some i ∈ {1, 2, …, k}. The size multipartite Ramsey number, denoted by mc(G1, G2, …, Gk), is the smallest positive integer s such that any k-coloring of the edges of Kc × s contains a monochromatic copy of Gi in color i for some i ∈ {1, 2, …, k}. In this paper, we establish some lower and upper bounds, and some exact values of multipartite Ramsey numbers for the union of stars.
Maximum average degree of list-edge-critical graphs and Vizing's conjecture Joshua Harrelson; Hannah Reavis
Electronic Journal of Graph Theory and Applications (EJGTA) Vol 10, No 2 (2022): 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.2022.10.2.4

Abstract

Vizing conjectured that χ′ℓ(G)≤Δ + 1 for all graphs. For a graph G and nonnegative integer k, we say G is a k-list-edge-critical graph if χ′ℓ(G)>k, but χ′ℓ(G − e)≤k for all e ∈ E(G). We use known results for list-edge-critical graphs to verify Vizing’s conjecture for G with mad(G)<(Δ + 3)/2 and Δ ≤ 9.
A generalization of a Turán’s theorem about maximum clique on graphs Douglas Frederico Guimarães Santiago; Anderson Luiz Pedrosa Porto; Kaio Ariel Silva Sá
Electronic Journal of Graph Theory and Applications (EJGTA) Vol 10, No 2 (2022): 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.2022.10.2.10

Abstract

One of the most important Turán’s theorems establishes an inequality between the maximum clique and the number of edges of a graph. Since 1941, this result has received much attention and many of the different proofs involve induction and a probability distribution. In this paper we detail finite procedures that gives a proof for the Turán’s Theorem. Among other things, we give a generalization of this result. Also we apply this results to a Nikiforov’s inequality between the spectral radius and the maximum clique of a graph.
Bounds on the connectivity of iterated line graphs Yehong Shao
Electronic Journal of Graph Theory and Applications (EJGTA) Vol 10, No 2 (2022): 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.2022.10.2.16

Abstract

For simple connected graphs that are neither paths nor cycles, we define l(G)=max{m : G has a divalent path of length m that is not both of length 2 and in a K3}, where a divalent path is a path whose internal vertices have degree two in G. Let G be a graph and Ln(G) be its n-th iterated line graph of G. We use κe′(G) and κ(G) for the essential edge connectivity and vertex connectivity of G, respectively. Let G be a simple connected graph that is not a path, a cycle or K1, 3, with l(G)=l ≥ 1. We prove that (i) for integers s ≥ 1, κ′e(Ll + s(G)) ≥ 2s + 2; (ii) for integers s ≥ 2, κ(Ll + s(G)) ≥ 2s − 1 + 2. The bounds are best possible.

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