Ars Combinatoria

ISSN 0381-7032 (print), 2817-5204 (online)

Ars Combinatoria is the oldest Canadian journal of combinatorics, established in 1976, dedicated to advancing combinatorial mathematics through the publication of high-quality, peer-reviewed research papers. Over the decades, it has built a strong international reputation and continues to serve as a leading platform for significant contributions to the field.
Open Access:  The journal follows the Diamond Open Access model—completely free for both authors and readers, with no article processing charges (APCs)
Publication Frequency: From 2024 onward, Ars Combinatoria publishes four issues annually—in March, June, September, and December.
Scope: Publishes research in all areas of combinatorics, including graph theory, design theory, enumeration, algebraic combinatorics, combinatorial optimization and related fields.
Indexing & Abstracting:  Indexed in MathSciNet, Zentralblatt MATH, and EBSCO, ensuring wide visibility and scholarly reach.
Rapid Publication: Submissions are processed efficiently, with accepted papers published promptly in the next available issue.
Print & Online Editions: Issues are available in both print and online formats to serve a broad readership.

Zhen-Bin Gao1
1College of Science, Harbin Engineering University ,Harbin, 150001, P.R.China
Abstract:

Lee and Wei defined super vertex-graceful labeling in 2006. In this paper, the generalized Butterfly Graph \(B_{n}^t\) and \(C_n^{(t)}\) graph are discussed. The generalized butterfly Graph \(B_{n}^t\) is super vertex-graceful when \(t\) (\(t > 0\)) is even, \(B_{n}^0\) is super vertex-graceful when \(n \equiv 0, 3 \pmod{4}\); For \(C_3^{(t)}\), there are: \(C_3^{(t)}\) is super vertex-graceful if and only if \(t = 1, 2, 3, 5, 7\). Moreover, we propose two conjectures on super vertex-graceful labeling.

Zhiwen Wang1,2
1School of Mathematics and Computer Science, Ningxia University, Yinchuen, Ningzia, 750081, P.R.China
2Department of Mathematics of Yeungnam University, Daedong, Kyongsan, Kyongbuk 712-749, Korea
Abstract:

An adjacent vertex distinguishing edge coloring, or an avd-coloring, of a simple graph \(G\) is a proper edge coloring of \(G\) such that for any two adjacent and distinct vertices \(u\) and \(v\) in \(G\), the set of colors assigned to the edges incident to \(u\) differs from the set of colors assigned to the edges incident to \(v\). In this paper, we prove that graphs with maximum degree \(3\) and with no isolated edges partly satisfy the adjacent vertex distinguishing edge coloring conjecture.

Zhendong Shao1, Roberto Solis-Oba2
1Department of Computer Science, the University of Western Ontario, London, ON, Canada.
2Department of Computer Science, the University of Western Ontario, London, ON, Canada.
Abstract:

An \(L(2,1)\)-labeling of a graph \(G\) is a function \(f\) from the vertex set \(V(G)\) to the set of all nonnegative integers such that \(|f(x) – f(y)| \geq 2\) if \(d(x,y) = 1\) and \(|f(x) – f(y)| \geq 1\) if \(d(x,y) = 2\), where \(d(x,y)\) denotes the distance between vertices \(x\) and \(y\) in \(G\). The \(L(2,1)\)-labeling number \(\lambda(G)\) of \(G\) is the smallest number \(k\) such that \(G\) has an \(L(2,1)\)-labeling with \(\max\{f(v) : v \in V(G)\} = k\). We consider Cartesian sums of graphs and derive, both, lower and upper bounds for the \(L(2,1)\)-labeling number of this class of graphs; we use two approaches to derive the upper bounds for the \(L(2,1)\)-labeling number and both approaches improve previously known upper bounds. We also present several approximation algorithms for computing \(L(2,1)\)-labelings for Cartesian sum graphs.

Mikko Pelto1
1 Turku Centre for Computer Science TUCS and Department of Mathematics University of Turku, FI-20014 Turku, Finland
Abstract:

Assume that \(G = (V, E)\) is an undirected graph with vertex set \(V\) and edge set \(E\). The ball \(B_r(v)\) denotes the vertices within graphical distance \(r\) from \(v\). A subset \(C \subseteq V\) is called an \(r\)-locating-dominating code if the sets \(I_r(v) = B_r(v) \cap C\) are distinct and non-empty for all \(v \in V \setminus C\). A code \(C\) is an \(r\)-identifying code if the sets \(I_r(v) = B_r(v) \cap C\) are distinct and non-empty for all vertices \(v \in V\). We study \(r\)-locating-dominating codes in the infinite king grid and, in particular, show that there is an \(r\)-locating-dominating code such that every \(r\)-identifying code has larger density. The infinite king grid is the graph with vertex set \(\mathbb{Z}^2\) and edge set \(\{(x_1, y_1), (x_2, y_2) \mid |x_1 – x_2| \leq 1, |y_1 – y_2| \leq 1, (x_1, y_1) \neq (x_2, y_2)\}\).

Pak Ching Li1
1Dept. of Computer Science University of Manitoba Winnipeg, Manitoba Canada R3T 2N2
Abstract:

An antimagic labeling of a graph with \(n\) vertices and \(m\) edges is a bijection from the set of edges to the integers \(1, 2, \ldots, m\) such that all \(n\) vertex sums are pairwise distinct. For a cycle \(C_n\) of length \(n\), the \(k\)-th power of \(C_n\), denoted by \(C_n^k\), is the supergraph formed by adding an edge between all pairs of vertices of \(C_n\) with distance at most \(k\). Antimagic labelings for \(C_n^k\) are given where \(k = 2, 3, 4\).

Radoslav Kirov1, Ramin Naimi2
1ScHOOL OF PHYSICAL AND MATHEMATICAL SCIENCES, NANYANG TECHNOLOGICAL UNIVERSITY, SINGAPORE 631317, SINGAPORE.
2DEPARTMENT OF MATHEMATICS, OCCIDENTAL COLLEGE, Los ANGELES, CA 90041, USA.
Abstract:

In 1990, Kostochka and Sidorenko proposed studying the smallest number of list-colorings of a graph \(G\) among all assignments of lists of a given size \(n\) to its vertices. We say a graph \(G\) is \(n\)-monophilic if this number is minimized when identical \(n\)-color lists are assigned to all vertices of \(G\). Kostochka and Sidorenko observed that all chordal graphs are \(n\)-monophilic for all \(n\). Donner (1992) showed that every graph is \(n\)-monophilic for all sufficiently large \(n\). We prove that all cycles are \(n\)-monophilic for all \(n\); we give a complete characterization of \(2\)-monophilic graphs (which turns out to be similar to the characterization of \(2\)-choosable graphs given by Erdős, Rubin, and Taylor in 1980); and for every \(n\) we construct a graph that is \(n\)-choosable but not \(n\)-monophilic.

Qin Chen1
1College of Science, China Jiliang University, Hangzhou 310018, P.R. China
Abstract:

An adjacent vertex distinguishing total coloring of a graph \(G\) is a proper total coloring of \(G\) such that no two adjacent vertices are incident to the same set of colors. The minimum number of colors needed for such a coloring is denoted by \(\chi_{at}(G)\). In this note, we prove that \(\chi_{at}(G) = 5\) for some cubic graphs.

S. Parameshwara Bhatta1, Shiju George1
1Department of Mathematics, Mangalore University, Mangalagangothri, 574 199, Karnataka State, INDIA.
Abstract:

In this paper, a generalized notion of the fixed point property,namely the \(n\)-fixed point property, for posets is discussed. The \(n\)-fixed point property is proved to be equivalent to the fixed point property in lattices. Further, it is shown that a poset of finite width has the \(n\)-fixed point property for some natural number \(n\) if and only if every maximal chain in it is a complete lattice.

Aijun Dong1, Qingsong Zou2, Guojun Li3
1 School of Science, Shandong Jiaotong University, Jinan, 250023, P. R. China
2Department of Mathematics, Xidian University, Xi’an, 710071, P. R. China
3School of Mathematics, Shandong University, Jinan, 250100, P. R. Cina
Abstract:

A graph is said to be equitably \(k\)-colorable if the vertex set \(V(G)\) can be partitioned into \(k\) independent subsets \(V_1, V_2, \ldots, V_k\) such that \(||V_i| – |V_j|| \leq 1\) (\(1 \leq i, j \leq k\)). A graph \(G\) is equitably \(k\)-choosable if, for any given \(k\)-uniform list assignment \(L\), \(G\) is \(L\)-colorable and each color appears on at most \(\lceil \frac{|V(G)|}{k} \rceil\) vertices. In this paper, we prove that if \(G\) is a graph such that \(\mathrm{mad}(G) \leq 3\), then \(G\) is equitably \(k\)-colorable and equitably \(k\)-choosable where \(k \geq \max\{\Delta(G), 5\}\).

S. Monikandan1, J. Balakumar1
1Department of Mathematics Manonmaniam Sundaranar University Tirunelveli-627 012 Tamil Nadu, INDIA.
Abstract:

For a vertex \(v\) of a graph \(G\), the unlabeled subgraph \(G-v\) is called a card of \(G\). We prove that the number of isolated vertices and the number of components of an \(n\)-vertex graph \(G\) can be determined from any collection of \(n-2\) of its cards for \(n \geq 10\). It is also proved that if two graphs of order \(n \geq 6\) have \(n-2\) cards in common, then the number of edges in them differs by at most one.