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.

Lian-Cui Zuo1,2, Jian-Liang Wu1, Jia-Zhuang Liu1
1School of Mathematics, Shandong University, Jinan, 250100, China
2School of Science, Jinan University, Jinan, 250002, China
Abstract:

The vertex linear arboricity \(vla(G)\) of a graph \(G\) is the minimum number of subsets into which the vertex set \(V(G)\) can be partitioned so that each subset induces a subgraph whose connected components are paths. An integer distance graph is a graph \(G(D)\) with the set of all integers as vertex set and two vertices \(u,v \in {Z}\) are adjacent if and only if \(|u-v| \in D\) where the distance set \(D\) is a subset of the positive integers set. Let \(D_{m,k} = \{1,2,\ldots,m\} – \{k\}\) for \(m > k \geq 1\). In this paper, some upper and lower bounds of the vertex linear arboricity of the integer distance graph \(G(D_{m,k})\) are obtained. Moreover, \(vla(G(D_{m,1})) = \lceil \frac{m}{4} \rceil +1\) for \(m \geq 3\), \(vla(G(D_{8l+1,2})) = 2l + 2\) for any positive integer \(l\) and \(vla(G(D_{4q,2})) = q+2\) for any integer \(q \geq 2\).

Bart De Bruyn1, Pieter Vandecasteele1
1Department of Pure Mathematics and Computer Algebra, Ghent University, Galglaan 2, B-8000 Gent, Belgium,
Abstract:

We determine all spreads of symmetry of the dual polar space \(H^D(2n-1,q^2)\). We use this to show the existence of glued near polygons of type \(H^D(2n_1-1,q^2) \otimes H^D(2n_2-1,q^2)\). We also show that there exists a unique glued near polygon of type \(H^D(2n_1-1,4) \otimes H^D(2n_2-1,4)\) for all \(n_1,n_2 \geq 2\). The unique glued near polygon of type \(H^D(2n-1,4) \otimes Q(2n_2-1,q^2)\) has the property that it contains \(H^D(2n-1,4)\) as a big geodetically closed sub near polygon. We will determine all dense near \((2n+2)\)-gons, \(n \geq 3\), which have \(H^D(2n-1,4)\) as a big geodetically closed sub near polygon. We will prove that such a near polygon is isomorphic to either \(H^D(2n+1,4)\), \(H^D(2n-1,4) \otimes Q(5,2)\) or \(H^D(2n-1,4) \times L\) for some line \(L\) of size at least three.

Gilbert B.Cagaanan1, Sergio R.Canoy,Jr.2
1Related Subjects Department School of Engineering Technology Mindanao State University – Iligan Institute of Technology 9200 Iligan City, Philippines
2Department of Mathematics College of Science and Mathematics Mindanao State University – Higan Institute of Technology 9200 Tligan City, Philippines
Abstract:

Given a connected graph \(G\) and two vertices \(u\) and \(v\) in \(G\), \(I_G[u, v]\) denotes the closed interval consisting of \(u\), \(v\) and all vertices lying on some \(u\)–\(v\) geodesic of \(G\). A subset \(S\) of \(V(G)\) is called a geodetic cover of \(G\) if \(I_G[S] = V(G)\), where \(I_G[S] = \cup_{u,v\in S} I_G[u, v]\). A geodetic cover of minimum cardinality is called a geodetic basis. In this paper, we give the geodetic covers and geodetic bases of the composition of a connected graph and a complete graph.

Marcia R.Cerioli1, Jayme L.Szwarcfiter2
1Universidade Federal do Rio de Janeiro, Instituto de Matemdtica and COPPE, Caixa Postal 68530, 21945-970, Rio de Janeiro, RJ, Brasil,
2Universidade Federal do Rio de Janeiro, Instituto de Matematica, Nticleo de Com- putac#o Eletrénica and COPPE, Caixa Postal 2324, 2001-970, Rio de Janeiro, RJ, Brasil.
Abstract:

Starlike graphs are the intersection graphs of substars of a star. We describe different characterizations of starlike graphs, including one by forbidden subgraphs. In addition, we present characterizations for a natural subclass of it, the starlike-threshold graphs.

J.D. Key1, J. Moori2, B.G. Rodrigues2
1Department of Mathematical Sciences Clemson University Clemson SC 29634, U.S.A.
2School of Mathematics, Statistics and Information Technology University of Natal-Pietermaritzburg Pietermaritzburg 3209, South Africa
Abstract:

We show that permutation decoding can be used, and give explicit PD-sets in the symmetric group, for some of the binary codes obtained from the adjacency matrices of the graphs on \(\binom{n}{3}\) vertices, for \(n \geq 7\), with adjacency defined by the vertices as \(3\)-sets being adjacent if they have zero, one or two elements in common, respectively.

Xianyong Meng1, Lianying Miao2, Bentang Su1, Rensuo Li1
1College of Information Science and| Engineering, Shandong Agriculture University, Taian, Shandong, 27100, China
2College of Science, China University of Mining and Technology, Xuzhou, Jiangsu, 221008, China
Abstract:

In this paper, we have discussed the dynamic coloring of a kind of planar graph. Let \(G\) be a Pseudo-Halin graph, we prove that the dynamic chromatic number of \(G\) is at most \(4\). Examples are given to show the bounds can be attained.

Peter J.Slater1, Yan Wang2
1Mathematical Sciences Department and Computer Science Department University of Alabama in Huntsville Huntsville, AL 35899 USA
2Department of Mathematics, Trinity College Hartford, CT 06106
Abstract:

In this paper, we shall consider acquisition sequences of a graph. The formation of each acquisition sequence is a process that creates an independent set. Each acquisition sequence is a sequence of “acquisitions” which are defined on a graph \( G \) for which each vertex originally has a value of one associated with it. In an acquisition, a vertex transfers all of its value to an adjacent vertex with equal or greater value. For an acquisition sequence, one continues until no more acquisitions are possible. The parameter \( a(G) \) is defined to be the minimum possible number of vertices with a nonzero value at the conclusion of such an acquisition sequence. Clearly, if \( S \) is a set of vertices with nonzero values at the end of some acquisition sequence, then \( S \) is independent, and we call such a set \( S \) an acquisition set. We show that for a given graph \( G \), “Is \( a(G) = 1 \)” is NP-complete, and describe a linear time algorithm to determine the acquisition number of a caterpillar.

Ian T. Roberts1, Sue D’Arcy1, Judith Egan1, Martin Griittmiiller2
1School of Engineering, Charles Darwin University Darwin NT 0909, Australia
2Department of Mathematics, University of Rostock 18051 Rostock, Germany
Abstract:

The cardinality of the minimal pairwise balanced designs on \( v \) elements with largest block size \( k \) is denoted by \( g^{(k)}(v) \). It is known that \( 31 \leq g^{(4)}(18) \leq 33 \). In this paper, we show that \( g^{(4)}(18) \neq 31 \).

Michelle Davidson1, Lynn Batten2
1Department of Mathematics University of Manitoba Winnipeg, Manitoba CANADA R3T 2N2
2School of Information Technology Deakin University 221 Burwood Highway Burwood 3125 AUSTRALIA
Abstract:

In 1966, Wagner used computational search methods to construct a \([23,14,5]\) code. This code has been examined with much interest since that time, in hopes of finding a geometric construction and possible code extensions. In this article, we give a simple geometric construction for Wagner’s code and consider extensions of this construction.

C.C. Lindner1, Giovanni Lo Faro2, Antoinette Tripodi2
1Department of Mathematics and Statistics, Auburn University, Auburn, Alabama 36849, USA
2Department of Mathematics, University of Messina Contrada Papardo,31-98166 Sant’Agata, Messina, Italy

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