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
- https://doi.org/10.61091/ojac-1801
- Full Text
- Online Journal of Analytic Combinatorics
- Issue 18, 2023
- Pages: 1-7 (Paper #1)
- Published: 31/12/2023
The aim of this paper is to introduce and study a new class of analytic functions which generalize the classes of \(\lambda\)-Spirallike Janowski functions. In particular, we gave the representation theorem, the right side of the covering theorem, starlikeness estimates and some properties related to the functions in the class \( S_\lambda ( T, H, F ) \).
- Research article
- https://doi.org/10.61091/ojac-1706
- Full Text
- Online Journal of Analytic Combinatorics
- Issue 17, 2022
- Pages: 1-10 (Paper #6)
- Published: 31/12/2022
criteria to verify log-convexity of sequences is presented. Iterating this criteria produces infinitely log-convex sequences. As an application, several classical examples of sequences arising in Combinatorics and Special Functions are presented. The paper concludes with a conjecture regarding coefficients of chromatic polynomials.
- Research article
- https://doi.org/10.61091/ojac-1705
- Full Text
- Online Journal of Analytic Combinatorics
- Issue 17, 2022
- Pages: 1-9 (Paper #5)
- Published: 31/12/2022
We discuss the VC-dimension of a class of multiples of integers and primes (equivalently indicator functions) and demonstrate connections to prime counting functions. Additionally, we prove limit theorems for the behavior of an empirical risk minimization rule as well as the weights assigned to the output hypothesis in AdaBoost for these “prime-identifying” indicator functions, when we sample \( mn \) i.i.d. points uniformly from the integers \(\{2, \ldots, n\}\).
- Research article
- https://doi.org/10.61091/ojac-1704
- Full Text
- Online Journal of Analytic Combinatorics
- Issue 17, 2022
- Pages: 1-14 (Paper #4)
- Published: 31/12/2022
Integer compositions and related counting problems are a rich and ubiquitous topic in enumerative combinatorics. In this paper we explore the definition of symmetric and asymmetric peaks and valleys over compositions. In particular, we compute an explicit formula for the generating function for the number of integer compositions according to the number of parts, symmetric, and asymmetric peaks and valleys.
- Research article
- https://doi.org/10.61091/ojac-1703
- Full Text
- Online Journal of Analytic Combinatorics
- Issue 17, 2022
- Pages: 1-29 (Paper #3)
- Published: 31/12/2022
In this paper we show some identities come from the \( q \)-identities of Euler, Jacobi, Gauss, and Rogers-Ramanujan. Some of these identities relate the function sum of divisors of a positive integer \( n \) and the number of integer partitions of \( n \). One of the most intriguing results found here is given by the next equation, for \( n > 0 \),
\[
\sum_{l=1}^n \frac{1}{l!} \sum_{w_1+w_2+\cdots+w_l \in C(n)} \frac{\sigma_1(w_1) \sigma_1(w_2) \cdots \sigma_1(w_l)}{w_1 w_2 \cdots w_l} = p_1(n),
\]
where \( \sigma_1(n) \) is the sum of all positive divisors of \( n \), \( p_1(n) \) is the number of integer partitions of \( n \), and \( C(n) \) is the set of integer compositions of \( n \). In the last section, we show seven applications, one of them is a series expansion for
\[
\frac{(q^{a_1};q^{b_1})_\infty (q^{a_2};q^{b_2})_\infty \cdots (q^{a_k};q^{b_k})_\infty}
{(q^{c_1};q^{d_1})_\infty (q^{c_2};q^{d_2})_\infty \cdots (q^{c_r};q^{d_r})_\infty},
\]
where \( a_1, \ldots, a_k, b_1, \ldots, b_k, c_1, \ldots, c_r, d_1, \ldots, d_r \) are positive integers, and \( |q| < 1 \).
- Research article
- https://doi.org/10.61091/ojac-1702
- Full Text
- Online Journal of Analytic Combinatorics
- Issue 17, 2022
- Pages: 1-10 (Paper #2)
- Published: 31/12/2022
Between Bernoulli/Euler polynomials and Pell/Lucas polynomials, convolution sums are evaluated in closed form via the generating function method. Several interesting identities involving Fibonacci and Lucas numbers are shown as consequences including those due to Byrd \( (1975) \) and Frontczak \( (2020) \).
- Research article
- https://doi.org/10.61091/ojac-1701
- Full Text
- Online Journal of Analytic Combinatorics
- Issue 17, 2022
- Pages: 1-8 (Paper #1)
- Published: 31/12/2022
The notion of length spectrum for natural numbers was introduced by Pong in \([5]\). In this article, we answer the question of how often one can recover a random number from its length spectrum. We also include a quick deduction of a result of LeVeque in \([4]\) on the average order of the size of length spectra.
- Research article
- https://doi.org/10.61091/ojac-1611
- Full Text
- Online Journal of Analytic Combinatorics
- Issue 16, 2021
- Pages: 1-20 (Paper #11)
- Published: 31/12/2021
This paper uses exponential sum methods to show that if \( E \subset M_2(\mathbb{Z}/p^r) \) is a finite set of \( 2 \times 2 \) matrices with sufficiently large density and \( j \) is any unit in the finite ring \( \mathbb{Z}/p^r \), then there exist at least two elements of \( E \) whose difference has determinant \( j \).
- Research article
- https://doi.org/10.61091/ojac-1610
- Full Text
- Online Journal of Analytic Combinatorics
- Issue 16, 2021
- Pages: 1-11 (Paper #10)
- Published: 31/12/2021
In this paper, we introduce a generalized family of numbers and polynomials of one or more variables attached to the formal composition \( f \cdot (g \circ h) \) of generating functions \( f \), \( g \), and \( h \). We give explicit formulae and apply the obtained result to two special families of polynomials; the first concerns the generalization of some polynomials applied to the theory of hyperbolic differential equations recently introduced and studied by \( M. \, Mihoubi \) and \( M. \, Sahari \). The second concerns two-variable Laguerre-based generalized Hermite-Euler polynomials introduced and should be updated to studied recently by \( N. \, U. \, Khan \, \textit{et al.} \).
- Research article
- https://doi.org/10.61091/ojac-1609
- Full Text
- Online Journal of Analytic Combinatorics
- Issue 16, 2021
- Pages: 1-12 (Paper #9)
- Published: 31/12/2021
In this paper, we show that the generalized exponential polynomials and the generalized Fubini polynomials satisfy certain binomial identities and that these identities characterize the mentioned polynomials (up to an affine transformation of the variable) among the class of the normalized Sheffer sequences.




