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 079
- Pages: 65-76
- Published: 30/04/2006
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 \(q \geq 2\).
- Research article
- Full Text
- Ars Combinatoria
- Volume 079
- Pages: 47-64
- Published: 30/04/2006
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.
- Research article
- Full Text
- Ars Combinatoria
- Volume 079
- Pages: 33-45
- Published: 30/04/2006
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.
- Research article
- Full Text
- Ars Combinatoria
- Volume 079
- Pages: 21-31
- Published: 30/04/2006
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.
- Research article
- Full Text
- Ars Combinatoria
- Volume 079
- Pages: 11-19
- Published: 30/04/2006
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.
- Research article
- Full Text
- Ars Combinatoria
- Volume 079
- Pages: 3-9
- Published: 30/04/2006
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.
- Research article
- Full Text
- Journal of Combinatorial Mathematics and Combinatorial Computing
- Volume 064
- Pages: 65-78
- Published: 29/02/2008
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.
- Research article
- Full Text
- Journal of Combinatorial Mathematics and Combinatorial Computing
- Volume 056
- Pages: 203-221
- Published: 28/02/2006
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 \( g^{(4)}(18) \neq 31 \).
- Research article
- Full Text
- Journal of Combinatorial Mathematics and Combinatorial Computing
- Volume 056
- Pages: 191-201
- Published: 28/02/2006
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.
- Research article
- Full Text
- Journal of Combinatorial Mathematics and Combinatorial Computing
- Volume 056
- Pages: 171-189
- Published: 28/02/2006




