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
- Journal of Combinatorial Mathematics and Combinatorial Computing
- Volume 092
- Pages: 81-91
- Published: 28/02/2015
The concept of fuzzy local \(\omega\)-language and Büchi fuzzy local \(\omega\)-language are defined in \([1,2]\). In this paper, we define Landweber fuzzy local \(\omega\)-language and study their closure properties and also give an automata characterization for it. Finally, we conclude the hierarchy among the subclasses of fuzzy regular \(\omega\)-languages.
- Research article
- Full Text
- Journal of Combinatorial Mathematics and Combinatorial Computing
- Volume 092
- Pages: 71-80
- Published: 28/02/2015
In this paper, we have calculated the combinatorial counting relations varying over the \(3\)-vertex paths of a simple graph \(G\), by restricting our attention to \(C_3\), \(C_4\)-free graphs.
- Research article
- Full Text
- Journal of Combinatorial Mathematics and Combinatorial Computing
- Volume 092
- Pages: 59-69
- Published: 28/02/2015
A kernel in a directed graph \(D(V, E)\) is a set \(S\) of vertices of \(D\) such that no two vertices in \(S\) are adjacent and for every vertex \(u\) in \(V \setminus S\) there is a vertex \(v\) in \(S\) such that \((u, v)\) is an arc of \(D\). The problem of existence of a kernel itself is NP-complete for a general digraph. But in this paper, we solve the strong kernel problem of certain oriented networks in polynomial time.
- Research article
- Full Text
- Journal of Combinatorial Mathematics and Combinatorial Computing
- Volume 092
- Pages: 47-57
- Published: 28/02/2015
A double shell is defined to be two edge-disjoint shells with a common apex. In this paper, we prove that double shells (where the shell orders are \(m\) and \(2m+1\)) with exactly two pendant edges at the apex are \(k\)-graceful when \(k=2\). We extend this result to double shells of any order \(m\) and \(\ell\) (where \(m \geq 3\) and \(\ell \geq 3\)) with exactly two pendant edges at the apex.
- Research article
- Full Text
- Journal of Combinatorial Mathematics and Combinatorial Computing
- Volume 092
- Pages: 39-46
- Published: 28/02/2015
A book consists of a line in the 3-dimensional space, called the spine, and a number of pages, each a half-plane with the spine as boundary. A book embedding \((\pi, p)\) of a graph consists of a linear ordering \(\pi\) of vertices, called the spine ordering, along the spine of a book and an assignment \(p\) of edges to pages so that edges assigned to the same page can be drawn on that page without crossing. That is, we cannot find vertices \(u, v, x, y\) with \(\pi(u) < \pi(x) < \pi(v) 2\) and \(C_n\) are given. If \(G\) is any graph, an upper bound for the page number of the Mycielski of \(G\) is given. When \(G\) and \(H\) are any two graphs with page number \(k\) and \(l\), it is proved that the amalgamation of \(G\) and \(H\) can be embedded in a \max(k, l)\) pages. Further, we remark that the amalgamation of \(G\) with itself requires the same number of pages as \(G\), irrespective of the vertices identified in the two copies of \(G\), to form an amalgamation.
- Research article
- Full Text
- Journal of Combinatorial Mathematics and Combinatorial Computing
- Volume 092
- Pages: 15-24
- Published: 28/02/2015
In 2004, Blinco et al [1] introduced \(\gamma\)-labeling. A function \(h\) defined on the vertex set of a graph \(G\) with \(n\) edges is called a \(\gamma\)-labeling if:
- \(h\) is a \(p\)-labeling of \(G\),
- \(G\) admits a tripartition \((A, B, C)\) with \(C = \{c\}\) and there exists \(\overline{b} \in B\) such that \((\overline{b}, c)\) is the unique edge with the property that \(h(c) – h(\overline{b}) = n\),
- for every edge \(\{a, v\} \in E(G)\) with \(a \in A\), \(h(a) < h(v)\).
In [1] they have also proved a significant result on graph decomposition that if a graph \(G\) with \(n\) edges admits a \(\gamma\)-labeling then the complete graph \(K_{2cn+1}\) can be cyclically decomposed into \(2cn + 1\) copies of the graph \(G\), where \(c\) is any positive integer.
Motivated by the result of Blinco et al [1], in this paper, we prove that the well-known almost-bipartite graph, the grid with an additional edge, \((P_m \Box P_n) + \hat{e}\), admits \(\gamma\)-labeling. Further, we discuss a related open problem.
- Research article
- Full Text
- Journal of Combinatorial Mathematics and Combinatorial Computing
- Volume 092
- Pages: 3-13
- Published: 28/02/2015
A set \( S \) of vertices of a graph \( G(V,E) \) is a \({dominating \;set}\) if every vertex of \( V \setminus S \) is adjacent to some vertex in \( S \). A dominating set is said to be \({efficient}\) if every vertex of \( V \setminus S \) is dominated by exactly one vertex of \( S \). A paired-dominating set is a dominating set whose induced subgraph contains at least one perfect matching. A set \( S \) of vertices in \( G \) is a total dominating set of \( G \) if every vertex of \( V \) is adjacent to some vertex in \( S \). In this paper, we construct a minimum paired dominating set and a minimum total dominating set for the infinite diamond lattice. The total domatic number of \( G \) is the size of a maximum cardinality partition of \( V \) into total dominating sets. We also demonstrate that the total domatic number of the infinite diamond lattice is 4.
- Research article
- https://doi.org/10.61091/ojac-1006
- Full Text
- Online Journal of Analytic Combinatorics
- Issue 10, 2015
- Pages: 1-18 (Paper #6)
- Published: 31/12/2015
A set of natural numbers tiles the plane if a square-tiling of the plane exists using exactly one square of side length n for every n in the set. In [9] it is shown that N, the set of all natural numbers, tiles the plane. We answer here a number of questions from that paper. We show that there is a simple tiling of the plane (no nontrivial subset of squares forms a rectangle). We show that neither the odd numbers nor the prime numbers tile the plane. We show that N can tile many, even infinitely many planes.
- Research article
- https://doi.org/10.61091/ojac-1005
- Full Text
- Online Journal of Analytic Combinatorics
- Issue 10, 2015
- Pages: 1-15 (Paper #5)
- Published: 31/12/2015
Let \( s, t \) be any numbers in \( \{0,1\} \) and let \( \pi = \pi_1 \pi_2 \cdots \pi_m \) be any word. We say that \( i \in [m-1] \) is an \( (s,t) \)-parity-rise if \( \pi_i \equiv s \pmod{2} \), \( \pi_{i+1} \equiv t \pmod{2} \), and \( \pi_i < \pi_{i+1} \). We denote the number of occurrences of \( (s,t) \)-parity-rises in \( \pi \) by \( \text{rise}_{s,t}(\pi) \). Also, we denote the total sizes of the \( (s,t) \)-parity-rises in \( \pi \) by \( \text{size}_{s,t}(\pi) \), that is, \( \text{size}_{s,t}(\pi) = \sum_{\pi_i < \pi_{i+1}} (\pi_{i+1} – \pi_i). \) A composition \( \pi = \pi_1 \pi_2 \cdots \pi_m \) of a positive integer \( n \) is an ordered collection of one or more positive integers whose sum is \( n \). The number of summands, namely \( m \), is called the number of parts of \( \pi \). In this paper, by using tools of linear algebra, we found the generating function that counts the number of all compositions of \( n \) with \( m \) parts according to the statistics \( \text{rise}_{s,t} \) and \( \text{size}_{s,t} \), for all \( s, t \).
- Research article
- https://doi.org/10.61091/ojac-1004
- Full Text
- Online Journal of Analytic Combinatorics
- Issue 10, 2015
- Pages: 1-5 (Paper #4)
- Published: 31/12/2015
In the paper, utilizing respectively the induction, a generating function of the Lah numbers, the Chu-Vandermonde summation formula, an inversion formula, the Gauss hypergeometric series, and two generating functions of Stirling numbers of the first kind, the authors collect and provide six proofs for an identity of the Lah numbers.




