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
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- Journal of Combinatorial Mathematics and Combinatorial Computing
- Volume 050
- Pages: 179-194
- Published: 31/08/2004
The previously studied notions of smart and foolproof finite order domination of a simple graph \( G = (V, E) \) are generalised in the sense that safe configurations in \( G \) are not merely sought after \( k \geq 1 \) moves, but in the limiting cases where \( k \to \infty \). Some general properties of these generalised domination parameters are established, after which the parameter values are found for certain simple graph structures (such as paths, cycles, multipartite graphs, and products of complete graphs, cycles, and paths).
- Research article
- Full Text
- Journal of Combinatorial Mathematics and Combinatorial Computing
- Volume 050
- Pages: 159-177
- Published: 31/08/2004
Self-dual codes are an important class of linear codes. Hadamard matrices and weighing matrices have been used widely in the construction of binary and ternary self-dual codes. Recently, weighing matrices and orthogonal designs have been used to construct self-dual codes over larger fields. In this paper, we further investigate codes over \( \mathbb{F}_p \), constructed from orthogonal designs. Necessary conditions for these codes to be self-dual are established, and examples are given for lengths up to 40. Self-dual codes of lengths \( 2n \geq 16 \) over \( GF(31) \) and \( GF(37) \) are investigated here for the first time. We also show that codes obtained from orthogonal designs can generally give better results, with respect to their minimum Hamming distance, than codes obtained from Hadamard matrices, weighing matrices, or conference matrices.
- Research article
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- Utilitas Mathematica
- Volume 050
- Pages: 149-157
- Published: 31/08/2004
We give decomposition formulas of the multiedge and the multipath zeta function of a regular covering of a graph \( G \) with respect to equivalence classes of prime, reduced cycles of \( G \). Furthermore, we give a decomposition formula of the weighted zeta function of a \( g \)-cyclic \( \Gamma \)-cover of a symmetric digraph \( D \) with respect to equivalence classes of prime cycles of \( D \), for any finite group \( \Gamma \) and \( g \in \Gamma \).
- Research article
- Full Text
- Journal of Combinatorial Mathematics and Combinatorial Computing
- Volume 050
- Pages: 141-148
- Published: 31/08/2004
Let \( A \) be an abelian group. We call a graph \( G = (V, E) \) \( A \)-magic if there exists a labeling \( f : E(G) \to A^* \) such that the induced vertex set labeling \( f^+ : V(G) \to A \), defined by \( f^+(v) = \sum_{(u,v) \in E(G)} f(u,v) \), is a constant map. In this paper, we present some algebraic properties of \( A \)-magic graphs. Using them, various results are obtained for group-magic eulerian graphs.
- Research article
- Full Text
- Journal of Combinatorial Mathematics and Combinatorial Computing
- Volume 050
- Pages: 129-140
- Published: 31/08/2004
Every Latin square of prime or prime power order \( s \) corresponds to a polynomial in 2 variables over the finite field on \( s \) elements, called the local permutation polynomial. What characterizes this polynomial is that its restrictions to one variable are permutations. We discuss the general form of local permutation polynomials and prove that their total degree is at most \( 2s – 4 \), and that this bound is sharp. We also show that the degree of the local permutation polynomial for Latin squares having a particular form is at most \( s – 2 \). This implies that circulant Latin squares of prime order \( p \) correspond to local permutation polynomials having degree at most \( p – 2 \). Finally, we discuss a special case of circulant Latin squares whose local permutation polynomial is linear in both variables.
- Research article
- Full Text
- Journal of Combinatorial Mathematics and Combinatorial Computing
- Volume 050
- Pages: 115-121
- Published: 31/08/2004
Two graphs are said to be flow-equivalent if they have the same number of nowhere-zero \( \lambda \)-flows, i.e., they have the same flow polynomial. In this paper, we present a few methods of constructing non-isomorphic flow-equivalent graphs.
- Research article
- Full Text
- Journal of Combinatorial Mathematics and Combinatorial Computing
- Volume 050
- Pages: 105-113
- Published: 31/08/2004
The Whitney number \( W_m{(n,k)} \) of the rank-\( n \) Dowling lattice \( Q_n(G) \) based on the group \( G \) having order \( m \) is the number of elements in \( Q_n(G) \) of co-rank \( k \). The associated numbers \( U_m{(n,k)} = k! W_m{(n,k)} \) and \( V_m{(n,k)} = k! m^k W_m{(n,k)} \) were studied by M. Benoumhani [\({Adv. in Appl. Math}\). 19 (1997), no. 1, 106-116] where a generating function was derived using algebraic techniques and logconcavity was shown for \( \{U_m{(n,k)}\} \) and for \( \{V_m{(n,k)}\} \). We give a central limit theorem and a local limit theorem on \( \mathbb{R} \) for \( \{U_m{(n,k)}\} \) and for \( \{V_m{(n,k)}\} \). In addition, asymptotic formulas for \( \max_k U_m{(n,k)} \), \( \max_k V_m{(n,k)} \) and their modes are given.
- Research article
- Full Text
- Journal of Combinatorial Mathematics and Combinatorial Computing
- Volume 050
- Pages: 95-104
- Published: 31/08/2004
The Picard group is defined as \( \Gamma = SL(2, \mathbb{Z}[i]) \); the ring of \( 2 \times 2 \) matrices with Gaussian integer entries and determinant one. We consider certain graphs associated to quotients \( \Gamma/\Gamma(p) \) where \( p \) is a prime congruent to three mod four and \( \Gamma(p) \) is the congruence subgroup of level \( p \). We prove a decomposition theorem on the vertices of these graphs, and use this decomposition to derive upper and lower bounds on their isoperimetric numbers.
- Research article
- Full Text
- Journal of Combinatorial Mathematics and Combinatorial Computing
- Volume 050
- Pages: 65-93
- Published: 31/08/2004
The domination number of a graph \( G \), \( \gamma(G) \), and the domination graph of a digraph \( D \), \( dom(D) \), are integrated in this paper. The \( \gamma \)-set di domination graph of the complete biorientation of a graph \( G \), \( dom_{\gamma}(\overset{\leftrightarrow}{G}) \), is created. All \( \gamma \)-sets of specific trees \( T \) are found, and \( dom_{\gamma}(\overset{\leftrightarrow}{T}) \) is characterized for those classes.
- Research article
- Full Text
- Journal of Combinatorial Mathematics and Combinatorial Computing
- Volume 050
- Pages: 57-64
- Published: 31/08/2004
A fractional automorphism of a graph is a doubly stochastic matrix which commutes with the adjacency matrix of the graph. If we apply an ordinary automorphism to a set of vertices with a particular property, such as being independent or dominating, the resulting set retains that property. We examine the circumstances under which fractional automorphisms preserve the fractional properties of functions on the vertex set.




