Utilitas Algorithmica (UA)
ISSN: xxxx-xxxx (print)
Utilitas Algorithmica (UA) is a premier, open-access international journal dedicated to advancing algorithmic research and its applications. Launched to drive innovation in computer science, UA publishes high-impact theoretical and experimental papers addressing real-world computational challenges. The journal underscores the vital role of efficient algorithm design in navigating the growing complexity of modern applications. Spanning domains such as parallel computing, computational geometry, artificial intelligence, and data structures, UA is a leading venue for groundbreaking algorithmic studies.
- Research article
- Full Text
- Ars Combinatoria
- Volume 123
- Pages: 215-230
- Published: 31/10/2015
In this paper, we generalize the notion of solid bursts from classical codes equipped with Hamming metric \([14]\) to array codes endowed with RT-metric \([13]\) and obtain some bounds on the parameters of RT-metric array codes for the correction and detection of solid burst array errors.
- Research article
- Full Text
- Ars Combinatoria
- Volume 123
- Pages: 207-214
- Published: 31/10/2015
Given a graph \(G = (V,E)\), a matching \(M\) of \(G\) is a subset of \(E\), such that every vertex of \(V\) is incident to at most one edge of \(M\). A \(k\)-matching is a matching with \(k\) edges. The total number of matchings in \(G\) is used in chemoinformatics as a structural descriptor of a molecular graph. Recently, Vesalian and Asgari (MATCH Commun. Math. Comput. Chem. \(69 (2013) 33–46\)) gave a formula for the number of \(5\)-matchings in triangular-free and \(4\)-cycle-free graphs based on the degrees of vertices and the number of vertices, edges, and \(5\)-cycles. But, many chemical graphs are not triangular-free or \(4\)-cycle-free, e.g., boron-nitrogen fullerene graphs (or BN-fullerene graphs). In this paper, we take BN-fullerene graphs into consideration and obtain formulas for the number of \(5\)-matchings based on the number of hexagons.
- Research article
- Full Text
- Ars Combinatoria
- Volume 123
- Pages: 195-206
- Published: 31/10/2015
This paper aims to provide a systematic investigation of the family of polynomials generated by the Rodrigues’ formulas
\[K_{n_1,n_2}^{(\alpha_1, \alpha_2)}(x, k,p) = (-1)^{n_1+n_2} e^{px^k}[\prod\limits_{j=1}^2x^{-\alpha}\frac{d^nj}{dx^{n_j}} (x)^{\alpha_j+n_j}]e^{-px^k},\]
and
\[M_{n_1,n_2}^{(\alpha_0,p_1,p_2)}(x, k) = \frac{(-1)^{n_1+n_2}}{p_1^{n_1}p_2^{p_2}}x^{-\alpha_0}[\prod\limits_ {j=1}^{2}e^{p_jx^k}\frac{d^nj}{dx^{n_j}}{dx^{n_j}}e^{-p_jx^k}]x^{n_1+n_2+\alpha_0},\]
These polynomials include the multiple Laguerre and the multiple Laguerre-Hahn polynomials, respectively. The explicit forms, certain operational formulas involving these polynomials with some applications, and linear generating functions for \(K_{n_1,n_2}^{(\alpha_1, \alpha_2)}(x, k,p)\) and \(M_{n_1,n_2}^{(\alpha_0,p_1,p_2)}(x, k)\) are obtained.
- Research article
- Full Text
- Ars Combinatoria
- Volume 123
- Pages: 185-194
- Published: 31/10/2015
For an \(n\)-connected graph \(G\), the \(n\)-wide diameter \(d_n(G)\), is the minimum integer \(m\) such that there are at least \(n\) internally disjoint \((di)\)paths of length at most \(m\) between any vertices \(x\) and \(y\). For a given integer \(l\), a subset \(S\) of \(V(G)\) is called an \((l, n)\)-dominating set of \(G\) if for any vertex \(x \in V(G) – S\) there are at least \(n\) internally disjoint \((di)\)paths of length at most \(l\) from \(S\) to \(z\). The minimum cardinality among all \((l, n)\)-dominating sets of \(G\) is called the \((l, n)\)-domination number. In this paper, we obtain that the \((l, n)\)-domination number of the \(d\)-ary cube network \(C(d, n)\) is \(2\) for \(1 \leq w \leq d\) and \(d_w(G) – f(d, n) \leq l \leq d_w(G) – 1 \) if \(d,n\geq 4\), where \(f(d, n) = \min\{e(\left\lfloor \frac{n}{2} \right\rceil + 1), \left\lfloor \frac{n}{2} \right\rfloor e\}\).
- Research article
- Full Text
- Ars Combinatoria
- Volume 123
- Pages: 169-184
- Published: 31/10/2015
Let \(k\) be a positive integer, and let \(G\) be a simple graph with vertex set \(V(G)\). A function \(f: V(G) \rightarrow \{-1, 1\}\) is called a signed \(k\)-dominating function if \(\sum_{u \in N(v)} f(u) \geq k\) for each vertex \(v \in V(G)\). A set \(\{f_1, f_2, \ldots, f_d\}\) of signed \(k\)-dominating functions on \(G\) with the property that \(\sum_{i=1}^{d} f_i(v) \leq 1\) for each \(v \in V(G)\), is called a signed \(k\)-dominating family (of functions) on \(G\). The maximum number of functions in a signed \(k\)-dominating family on \(G\) is the signed \(k\)-domatic number of \(G\), denoted by \(d_{kS}(G)\). In this paper, we initiate the study of signed \(k\)-domatic numbers in graphs and we present some sharp upper bounds for \(d_{kS}(G)\). In addition, we determine the signed \(k\)-domatic number of complete graphs.
- Research article
- Full Text
- Ars Combinatoria
- Volume 123
- Pages: 159-167
- Published: 31/10/2015
In this paper, \(E_2\)-cordiality of a graph \(G\) is considered. Suppose \(G\) contains no isolated vertex, it is shown that \(G\) is \(E_2\)-cordial if and only if \(G\) is not of order \(4n + 2\).
- Research article
- Full Text
- Ars Combinatoria
- Volume 123
- Pages: 151-158
- Published: 31/10/2015
A Hamiltonian walk of a connected graph \(G\) is a closed spanning walk of minimum length in \(G\). The length of a Hamiltonian walk in \(G\) is called the Hamiltonian number, denoted by \(h(G)\). An Eulerian walk of a connected graph \(G\) is a closed walk of minimum length which contains all edges of \(G\). In this paper, we improve some results in [5] and give a necessary and sufficient condition for \(h(G) < e(G)\). Then we prove that if two nonadjacent vertices \(u\) and \(v\) satisfying that \(\deg(u) + \deg(v) \geq |V(G)|\), then \(h(G) = h(G + uv)\). This result generalizes a theorem of Bondy and Chvatal for the Hamiltonian property. Finally, we show that if \(0 \leq k \leq n-2\) and \(G\) is a 2-connected graph of order \(n\) satisfying \(\deg(u) + \deg(v) + \deg(w) \geq \frac{3n+k-2}{2}\) for every independent set \(\{u,v,w\}\) of three vertices in \(G\), then \(h(G) \leq n+k\). It is a generalization of Bondy's result.
- Research article
- Full Text
- Ars Combinatoria
- Volume 123
- Pages: 125-150
- Published: 31/10/2015
Let \(G\) be a finite abelian group of order \(n\). The barycentric Ramsey number \(BR(H,G)\) is the minimum positive integer \(r\) such that any coloring of the edges of the complete graph \(K_r\) by elements of \(G\) contains a subgraph \(H\) whose assigned edge colors constitute a barycentric sequence, i.e., there exists one edge whose color is the “average” of the colors of all edges in \(H\). When the number of edges \(e(H) \equiv 0 \pmod{\exp(G)}\), \(BR(H,G)\) are the well-known zero-sum Ramsey numbers \(R(H,G)\). In this work, these Ramsey numbers are determined for some graphs, in particular, for graphs with five edges without isolated vertices using \(G = \mathbb{Z}_n\), where \(2 \leq n \leq 4\), and for some graphs \(H\) with \(e(H) \equiv 0 \pmod{2}\) using \(G = \mathbb{Z}_2^s\).
- Research article
- Full Text
- Journal of Combinatorial Mathematics and Combinatorial Computing
- Volume 094
- Pages: 313-321
- Published: 31/08/2015
Hrnciar and Haviar [3] gave a method to construct a graceful labeling for all trees of diameter at most five. Based on their method and the methods described in Balbuena et al. [1], we shall describe a new construction for gracefully labeled trees by attaching trees to the vertices of a tree admitting a bipartite graceful labeling.
- Research article
- Full Text
- Journal of Combinatorial Mathematics and Combinatorial Computing
- Volume 094
- Pages: 301-312
- Published: 31/08/2015
Given two graphs \( G \) and \( H \) and a function \( f \subset V(G) \times V(H) \), Hedetniemi [9] defined the \emph{function graph} \( GfH \) by \( V(GfH) = V(G) \cup V(H) \) and \( E(GfH) = E(G) \cup E(H) \cup \{uv \mid v : f(u)\} \). Whenever \( G \cong H \), the function graph was called a functigraph by Chen, Ferrero, Gera, and Yi [7]. A function graph is a generalization of the \( \alpha \)-permutation graph introduced by Chartrand and Harary [5]. The independence number of a graph is the size of a largest set of mutually non-adjacent vertices. In this paper, we study independence number in function graphs. In particular, we give a lower bound in terms of the order and the chromatic number, which improves on some elementary results and has a number of interesting corollaries.




