8 citations · 31 across the 33 of their papers we have counts for
37 papers
Strong NP-Completeness of Unrestricted Balanced Mobiles
Andrei Popa, Alexandru Popa
A mobile is a rooted full binary tree whose leaves carry positive integer weights. The imbalance of an internal node is the absolute difference between the total weights of its two…
A decomposition of Weyl group multiple Dirichlet series for symmetrizable Kac-Moody root systems
Alexandru A. Popa, Jack Walsh
We study twisted Weyl group multiple Dirichlet series attached to symmetrizable Kac-Moody root systems, using the Chinta-Gunnells method to construct their -parts. Our main resu…
Complexity and Algorithms for Unary Translocation Distance
Maria Constantin, Adrian Miclăuş, Alexandru Popa +1
Given a finite set of integers , a \emph{unary translocation} produces a new set , where and are nonnegative integers satisfying for some…
Residues of quadratic Weyl group multiple Dirichlet series
Adrian Diaconu, Bogdan Ion, Vicenţiu Paşol +1
We give explicit formulas for the residue of the Chinta-Gunnells average attached to a finite irreducible root system, at the polar divisor corresponding to a simple short root. Th…
A trace formula for Hecke operators on Fuchsian groups
Alexandru A. Popa
In this paper we give a trace formula for Hecke operators acting on the cohomology of a Fuchsian group of finite covolume, with coefficients in a module . The proof is based on…
Quadratic Weyl group multiple Dirichlet series of Type
Adrian Diaconu, Vicenţiu Paşol, Alexandru A. Popa
In this paper and its sequel \cite{DPP}, we investigate the precise relationship between the quadratic affine Weyl group multiple Dirichlet series in the sense of \cite{CG1, BD}, a…
Approximate and exact results for the harmonious chromatic number
Ruxandra Marinescu-Ghemeci, Camelia Obreja, Alexandru Popa
Graph colorings is a fundamental topic in graph theory that require an assignment of labels (or colors) to vertices or edges subject to various constraints. We focus on the harmoni…
A novel algorithm for clearing financial obligations between companies -- an application within the Romanian Ministry of Economy
Lucian-Ionut Gavrila, Alexandru Popa
The concept of clearing or netting, as defined in the glossaries of European Central Bank, has a great impact on the economy of a country influencing the exchanges and the interact…
A decision support system for optimizing the cost of social distancing in order to stop the spread of COVID-19
Alexandru Popa
Currently there are many attempts around the world to use computers, smartphones, tablets and other electronic devices in order to stop the spread of COVID-19. Most of these attemp…
IP Solutions for International Kidney Exchange Programmes
Péter Biró, Márton Gyetvai, Radu Stefan Mincu +2
In kidney exchange programmes patients with end-stage renal failure may exchange their willing, but incompatible living donors among each other. National kidney exchange programmes…
Heuristic algorithms for the Longest Filled Common Subsequence Problem
Radu Stefan Mincu, Alexandru Popa
At CPM 2017, Castelli et al. define and study a new variant of the Longest Common Subsequence Problem, termed the Longest Filled Common Subsequence Problem (LFCS). For the LFCS pro…
NewsCompare - a novel application for detecting news influence in a country
Cristian Pop, Alexandru Popa
The concept of `fake news' has been referenced and thrown around in news reports so much in recent years that it has become a news topic in its own right. At its core, it poses a c…
Complexity of Computing the Anti-Ramsey Numbers for Paths
Saeed Akhoondian Amiri, Alexandru Popa, Mohammad Roghani +3
The anti-Ramsey numbers are a fundamental notion in graph theory, introduced in 1978, by Erd\" os, Simonovits and S\' os. For given graphs and the \emph{anti-Ramsey number}…
Analytic Geometry of Homogeneous Spaces
Alexandru Popa
The theory uses methods and language of linear algebra to study nonlinear spaces. These techniques can be used particularly to describe analytic geometry of non-linear elliptic, hy…
A connection between String Covers and Cover Deterministic Finite Tree Automata Minimization
Alexandru Popa, Andrei Tanasescu
Data compression plays a crucial part in the cloud based systems of today. One the fundaments of compression is quasi-periodicity, for which there are several models. We build upon…
Hardness and algorithmic results for the approximate cover problem
Alexandru Popa, Andrei Tanasescu
In CPM 2017, Amir et al. introduce a problem, named \emph{approximate string cover} (\textbf{ACP}), motivated by many aplications including coding and automata theory, formal langu…
An output-sensitive algorithm for the minimization of 2-dimensional String Covers
Alexandru Popa, Andrei Tanasescu
String covers are a powerful tool for analyzing the quasi-periodicity of 1-dimensional data and find applications in automata theory, computational biology, coding and the analysis…
The use of a pruned modular decomposition for Maximum Matching algorithms on some graph classes
Guillaume Ducoffe, Alexandru Popa
We address the following general question: given a graph class C on which we can solve Maximum Matching in (quasi) linear time, does the same hold true for the class of graphs that…
A quasi linear-time b-Matching algorithm on distance-hereditary graphs and bounded split-width graphs
Guillaume Ducoffe, Alexandru Popa
We present a quasi linear-time algorithm for Maximum Matching on distance-hereditary graphs and some of their generalizations. This improves on [Dragan, WG'97], who proposed such a…
Heuristic algorithms for the min-max edge 2-coloring problem
Radu Stefan Mincu, Alexandru Popa
In multi-channel Wireless Mesh Networks (WMN), each node is able to use multiple non-overlapping frequency channels. Raniwala et al. (MC2R 2004, INFOCOM 2005) propose and study sev…
A simple proof of the Eichler-Selberg trace formula
Alexandru A. Popa, Don Zagier
We give a short proof of the trace formula for Hecke operators on modular forms for the modular group, using the action of Hecke operators on the space of period polynomials.
Fully polynomial FPT algorithms for some classes of bounded clique-width graphs
David Coudert, Guillaume Ducoffe, Alexandru Popa
Parameterized complexity theory has enabled a refined classification of the difficulty of NP-hard optimization problems on graphs with respect to key structural properties, and so…
On the trace formula for Hecke operators on congruence subgroups, II
Alexandru A. Popa
In a previous paper, we obtained a general trace formula for double coset operators acting on modular forms for congruence subgroups, expressed as a sum over conjugacy classes. Her…
A generalization of Ramanujan's congruence to modular forms of prime level
Radu Gaba, Alexandru A. Popa
We prove congruences between cuspidal newforms and Eisenstein series of prime level, which generalize Ramanujan's congruence. Such congruences were recently found by Billerey and M…