Publisher: Vilnius University   (Total: 38 journals)   [Sort by number of followers]

Showing 1 - 38 of 38 Journals sorted alphabetically
Accounting Theory and Practice     Open Access   (Followers: 10)
Acta medica Lituanica     Open Access  
Acta Paedagogica Vilnensia     Open Access  
Archaeologia Lituana     Open Access  
Baltic J. of Political Science     Open Access   (Followers: 1)
Baltistica     Open Access  
Criminological Studies     Open Access  
Ekonomika (Economics)     Open Access  
Informacijos mokslai     Open Access  
J.ism Research     Open Access   (Followers: 5)
Jaunujų mokslininkų darbai     Open Access   (Followers: 2)
Kalbotyra     Open Access  
Knygotyra (Book Science)     Open Access  
Lietuvių kalba     Open Access  
Lietuvos istorijos studijos     Open Access  
Lietuvos Matematikos Rinkinys     Open Access  
Lietuvos Statistikos Darbai     Open Access   (Followers: 1)
Literatūra     Open Access  
Lithuanian Surgery : Lietuvos Chirurgija     Open Access  
Nonlinear Analysis : Modelling and Control     Open Access   (Followers: 1)
Organizations and Markets in Emerging Economies     Open Access   (Followers: 1)
Politologija     Open Access  
Problemos     Open Access  
Psychology     Open Access  
Religija ir kultūra     Open Access  
Respectus Philologicus     Open Access  
Scandinavistica Vilnensis     Open Access  
Semiotika     Open Access  
Slavistica Vilnensis     Open Access   (Followers: 1)
Socialinė teorija, empirija, politika ir praktika     Open Access  
Socialiniai tyrimai     Open Access  
Sociology : Thought and Action     Open Access  
Taikomoji kalbotyra     Open Access   (Followers: 2)
Teisė : Law     Open Access  
Verbum     Open Access   (Followers: 1)
Vertimo studijos (Translation Studies)     Open Access   (Followers: 1)
Vilnius University Open Series     Open Access  
Vilnius University Proceedings     Open Access  
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Lietuvos Matematikos Rinkinys
Number of Followers: 0  

  This is an Open Access Journal Open Access journal
ISSN (Print) 0132-2818 - ISSN (Online) 2335-898X
Published by Vilnius University Homepage  [38 journals]
  • Plateau problem and minimal surfaces: numerical methods and applications

    • Authors: Mifodijus Sapagovas
      Pages: 1 - 15
      Abstract: This article presents an overview of the results of solving the minimal surface equation by numerical methods. Another research task is the application of minimal surfaces in science, technology, especially architecture. The article is illustrated with examples of the application of minimal surfaces.
      Keywords: Articles ; On using a non-probability sample for the estimation of population
             parameters

      • Authors: Ieva Burakauskaitė, Andrius Čiginas
        Pages: 1 - 11
        Abstract: We aim to find a way to effectively integrate a non-probability (voluntary) sample under the data framework, where the study variable is also observed in a probability sample of some statistical survey. The selection bias that arises from voluntary participation in the survey is corrected by estimating the inclusion into the sample probabilities (propensity scores) for the units in the non-probability sample. The estimators for the propensity scores are constructed using a parametric logistic regression model. We consider two modeling scenarios: with an assumption that the willingness to participate in the voluntary survey does not depend on the survey variable itself and that such a variable does contribute to whether the individual responds or not. The maximum likelihood method is applied in both scenarios to estimate the propensity scores. The estimators of the population mean based on the estimated propensity scores are linearly combined with the unbiased estimator using the probability sample data. We compare the constructed estimators in the simulation study, where we estimate the population proportions using data from the Population and Housing Census surveys.
        Keywords: Articles ; fANOVA application for comparison of companies by the CEO turnover rates

        • Authors: Urtė Deinoravičiūtė, Anna Yasyreva
          Pages: 12 - 24
          Abstract: The aim of this study was to analyze the data from the Nasdaq Baltic listed companies’ financial statements and to estimate if the CEO changes have a significant influence on the financial performance: profitability, indebtedness and stock price. Data was collected and financial ratios were computed for 34 companies during 2006 to 2021 (2008 to 2022 for stock prices). The companies were divided into 3 groups: ones that had no CEO changes over the period; those that had 1 or 2 and those with 3 or more. Point-wise ANOVA, fANOVA and fMANOVA were conducted. Both point-wise and functional ANOVA indicated that there is a significant difference of at least one group from the others in terms of ROA and EBITDA margin. After conducting two-sample tests, the group with 3 or more CEO changes was identified as having a significantly higher EBITDA margin than the others. Furthermore, a significant positive relationship between the stock price and the CEO turnover was uncovered in the function-on-scalar regression results.
          Keywords: Articles ; Problems for combinatorial numbers satisfying a class of triangular arrays

          • Authors: Igoris Belovas
            Pages: 16 - 22
            Abstract: Numbers satisfying a class of triangular arrays, defined by a bivariate first-order linear difference equation with linear coefficients, include a wide range of combinatorial numbers: binomial coefficients, Morgan numbers, Stirling numbers of the first and the second types, non-central Stirling numbers, Eulerian numbers, Lah numbers, and their generalizations. In this work, we derive the general analytic expression of the numbers satisfying a class of triangular arrays and propose problems (both teaching and unsolved ones) for undergraduates studying probability theory and analytical combinatorics subjects in the study programs of the fields of mathematics and computer science. Some of the unsolved challenges can also be used as the basis for a thesis.
            Keywords: Articles ; On the uniform distribution of endomorphisms of sdimensional torus, II

            • Authors: Birutė Kryžienė, Gintautas Misevičius
              Pages: 19 - 23
              Abstract: There is not abstract.
              Keywords: Articles
              PubDate: 2023-09-21
              DOI: 10.15388/LMR.2006.30565
               
          • On the calculation of integer sequences, associated with twin primes

            • Authors: Igoris Belovas, Martynas Sabaliauskas, Paulius Mykolaitis
              Pages: 23 - 29
              Abstract: The twin primes conjecture states that there are infinitely many twin primes. While studying this hypothesis, many important results were obtained, but the problem remains unsolved. In this work, the problem is studied from the side of experimental mathematics. Using the probabilistic Miller–Rabin primality test and parallel computing technologies, the distribution of prime pairs in the intervals (2n; 2n+1] is studied experimentally.
              Keywords: Articles ; Investigation of an attack on the multi-prime RSA cryptosystem based on
                     cubic equations

              • Authors: Aleksėjus Michalkovič, Jokūbas Žitkevičius
                Pages: 25 - 35
                Abstract: In this paper we consider a modification of the attack on the classic RSA cryptosystem aimed at factoring the public modulus n, which is a product of three primes. To improve the performance of the modified attack we introduce additional parameters. We present the theoretical upper bound on the search range parameter and define a shifting parameter based on the empirical results. Since these changes make our attack probabilistic, we investigate the dependence of the success on the values of the newly defined parameters.
                Keywords: Articles ; The Mellin transform of the square of the Riemann zeta-function in the
                       critical strip

                • Authors: Mindaugas Stoncelis
                  Pages: 28 - 31
                  Abstract: There is not abstract
                  Keywords: Articles
                  PubDate: 2023-09-21
                  DOI: 10.15388/LMR.2006.30567
                   
              • Local asymptotic normality of statistical models of discrete martingales

                • Authors: Vaidotas Kanišauskas
                  Pages: 30 - 40
                  Abstract: We establish general conditions assuring the local asymptotic normality of statistical experiments of discrete or purely discontinuous local martingales obtained models of point processes of all types were found out. The general conditions include the Fréchet differentiability of parameters in probability in normed spaces with regard to a continuous compensator.
                  Keywords: Articles ; Air quality investigation using functional data analysis methods

                  • Authors: Akvilė Vitkauskaitė, Milda Salytė
                    Pages: 36 - 53
                    Abstract: In this research paper, a comprehensive analysis of particulate matter (PM10) and nitrogen dioxide (NO2) pollution concentrations in six different Lithuanian regions is presented. The analysis employs data smoothing, principal component analysis (PCA), exploratory data analysis, hypothesis testing, and time series analysis to provide a thorough examination. Functional data analysis approaches were used to find the origins and effects of these air pollutants by revealing their data patterns. The functional data analysis techniques demonstrate their effectiveness in revealing deep links within large datasets, assisting in the control of air quality problems. This research provides valuable insights into air quality challenges in Lithuanian regions. The study, aimed at comparing air quality across different regions, indicates that there are no significant differences in PM10 and NO2 between the two groups. Notably, reliable forecasts for 2023 data are attainable for PM10 in regions such as Vilnius Old Town, Vilnius Lazdynai, Šiauliai, and Klaipėda. For NO2, successful forecasting can be applied to Vilnius Old Town, Vilnius Lazdynai, and Šiauliai.
                    Keywords: Articles ; Comparison of ``What numbers make sense''' problems solving in the Czech
                           Republic and Lithuania

                    • Authors: Ieva Kilienė
                      Pages: 41 - 47
                      Abstract: Word problems pose many challenges for students. One of them is the failure to understand the task conditions and the mechanical solution of the problem. This problem can be addressed by incorporating non-standard word problems into the learning process.  The article reviews the type of non-standard word problems called ``Where numbers make sense''' and discusses its potential applications. It also presents the results of a study conducted with students from Lithuania and the Czech Republic.
                      Keywords: Articles ; sites.google.com/view/Lapinskas – Mathematical readings

                      • Authors: Remigijus Lapinskas
                        Pages: 48 - 49
                        Abstract: This article is about the author's online book "Mathematical Readings" [2]. The book presents the high school math course in a slightly different way than conventional textbooks, the work focuses less on routine problems and tries to examine mathematical concepts in a broader context. The book makes frequent use of mobile math apps and the R program, and links to online sources are often provided. The text may be useful for self-study and math circles.
                        Keywords: Articles ; Proofs without words

                        • Authors: Edmundas Mazėtis, Grigorijus Melničenko
                          Pages: 50 - 58
                          Abstract: Usually, proofs of mathematical statements involve both algebraic rearrangements and logical reasoning. But there are mathematical statements whose truth is obvious at first glance when there is a diagram illustrating that proof. Although the proofs based on the drawing are not necessarily full and complete, but the drawing helps to notice facts that are then easily supported by algebra and logic. The paper presents proofs of mathematical propositions where, upon careful study of the drawing, the main idea of the proof can be seen from the drawing, and the proof itself becomes beautiful and clear.
                          Keywords: Articles ; Concepts, terms and symbols in mathematics textbooks

                          • Authors: Rimas Norvaiša
                            Pages: 59 - 74
                            Abstract: The article discusses the problems of definitions of concepts of school mathematics in textbooks. Excerpts from textbooks show  how interpretations of a fraction having no necessary properties of a mathematical definition have changed over the decades. The alternative of a concept of a fraction based on the number line is discussed.
                            Keywords: Articles ; Revised national mathematics curriculum: improving competence in
                                   mathematical communication through teaching methods

                            • Authors: Gabija Pranaitytė, Violeta Kravčenkienė, Bronė Narkevičienė
                              Pages: 75 - 86
                              Abstract: The article delves into the topic of mathematical communication development, a key competence outlined in the updated National Mathematics Curriculum. It explores the integration of this competence within the context of the revised curriculum, examining relevant research on mathematical communication and teaching methodologies to foster its growth. Suggestions for pedagogical strategies aimed at enhancing mathematical communication are presented.
                              Keywords: Articles ; A critique of terms and symbols in school mathematics

                              • Authors: Robertas Vilkas
                                Pages: 87 - 97
                                Abstract: Criticism of some terms and symbols of school mathematics is presented, and recommendations are given. The problem of writing decimal fractions using a comma and the resulting semicolon when separating such numbers, which contradicts not only the international symbols of mathematics, but also the general rules of the Lithuanian language, is discussed separately. The incorrect use of the concept of an elementary event not only in schools, but also in universities, is discussed in more detail.
                                Keywords: Articles ; Definition of an increasing function

                                • Authors: Robertas Vilkas
                                  Pages: 98 - 113
                                  Abstract: Some nuances of applications of the general definition of an increasing (decreasing, non-decreasing, non-increasing) function are discussed. The question of concern to teachers is answered:  can a function be increasing not only on an open interval'
                                  Keywords: Articles ; Do we need mixed numbers'

                                  • Authors: Robertas Vilkas
                                    Pages: 114 - 123
                                    Abstract: Many reasons are given for not using mixed numbers.
                                    Keywords: Articles ; Application of the methods of monotonic sequences

                                    • Authors: Juozas Juvencijus Mačys
                                      Pages: 270 - 274
                                      Abstract: The method of monotonic sequences (see [1], [2]) is considered and the issue of its exactness is discussed. It is shown how the method can be applied to finite sums with a large number of summands.
                                      Keywords: Articles ; Analysis of passivity problems in the baltic equity market

                                      • Authors: Igoris Belovas, Audrius Kabašinskas, Leonidas Sakalauskas
                                        Pages: 289 - 294
                                        Abstract: The Baltic States equity market is a challenge for investors and financial analysts. Unfortunately strong  assivity is observed in ``young'' markets, therefore any (Gaussian, α-stable etc) distribution fitting tests (Anderson–Darling, Kolmogorov–Smirnov, etc.) are poorly applicable. Improvement based on mixed distributions is proposed and its adequacy in the Baltic States market is tested. In this paper we use Koutrouvelis goodness-of-fit test and modified χ2 test.
                                        Keywords: Articles ; The numerical model of the dynamics of asset prices

                                        • Authors: Eimutis Valakevičius
                                          Pages: 295 - 302
                                          Abstract: In the article is proposed the algorithm how to model the dynamics of asset prices by Markov process with continuous time and countable set of states.
                                          Keywords: Articles ;
                                           
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Publisher: Vilnius University   (Total: 38 journals)   [Sort by number of followers]

Showing 1 - 38 of 38 Journals sorted alphabetically
Accounting Theory and Practice     Open Access   (Followers: 10)
Acta medica Lituanica     Open Access  
Acta Paedagogica Vilnensia     Open Access  
Archaeologia Lituana     Open Access  
Baltic J. of Political Science     Open Access   (Followers: 1)
Baltistica     Open Access  
Criminological Studies     Open Access  
Ekonomika (Economics)     Open Access  
Informacijos mokslai     Open Access  
J.ism Research     Open Access   (Followers: 5)
Jaunujų mokslininkų darbai     Open Access   (Followers: 2)
Kalbotyra     Open Access  
Knygotyra (Book Science)     Open Access  
Lietuvių kalba     Open Access  
Lietuvos istorijos studijos     Open Access  
Lietuvos Matematikos Rinkinys     Open Access  
Lietuvos Statistikos Darbai     Open Access   (Followers: 1)
Literatūra     Open Access  
Lithuanian Surgery : Lietuvos Chirurgija     Open Access  
Nonlinear Analysis : Modelling and Control     Open Access   (Followers: 1)
Organizations and Markets in Emerging Economies     Open Access   (Followers: 1)
Politologija     Open Access  
Problemos     Open Access  
Psychology     Open Access  
Religija ir kultūra     Open Access  
Respectus Philologicus     Open Access  
Scandinavistica Vilnensis     Open Access  
Semiotika     Open Access  
Slavistica Vilnensis     Open Access   (Followers: 1)
Socialinė teorija, empirija, politika ir praktika     Open Access  
Socialiniai tyrimai     Open Access  
Sociology : Thought and Action     Open Access  
Taikomoji kalbotyra     Open Access   (Followers: 2)
Teisė : Law     Open Access  
Verbum     Open Access   (Followers: 1)
Vertimo studijos (Translation Studies)     Open Access   (Followers: 1)
Vilnius University Open Series     Open Access  
Vilnius University Proceedings     Open Access  
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School of Mathematical and Computer Sciences
Heriot-Watt University
Edinburgh, EH14 4AS, UK
Email: journaltocs@hw.ac.uk
Tel: +00 44 (0)131 4513762
 


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