{"title":"On some generalizations of multiplicative operators on the space h(g)","authors":"Yu. S. Linchuk","doi":"10.31861/bmj2019.01.056","DOIUrl":"https://doi.org/10.31861/bmj2019.01.056","url":null,"abstract":"","PeriodicalId":196726,"journal":{"name":"Bukovinian Mathematical Journal","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115704118","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Multifrequency systems of dierential equations were studied with the help of averaging method in the works by R.I. Arnold, Ye.O. Grebenikov, Yu.O. Mitropolsky, A.M. Samoilenko and many other scientists. The complexity of the study of such systems is their inherent resonant phenomena, which consist in the rational complete or almost complete commensurability of frequencies. As a result, the solution of the system of equations averaged over fast variables in the general case may deviate from the solution of the exact problem by the quantity O (1). The approach to the study of such systems, which was based on the estimation of the corresponding oscillating integrals, was proposed by A.M. Samoilenko, which allowed to obtain in the works by A.M. Samoilenko and R.I. Petryshyn a number of important results for multifrequency systems with initial , boundary and integral conditions. For multifrequency systems with an argument delay, the averaging method is substantiated in the works by Ya.Y. Bihun, R.I. Petryshyn, I.V. Krasnokutska and other authors. In this paper, the averaging method is used to study the solvability of a multifrequency system with an arbitrary nite number of linearly transformed arguments in slow and fast variables and integral conditions for slow and fast variables on parts of the interval [0, L] of the system of equations. An unimproved estimate of the error of the averaging method under the superimposed conditions is obtained, which clearly depends on the small parameter and the number of linearly transformed arguments in fast variables.
{"title":"AVERAGING IN MULTIFREQUENCY SYSTEMS WITH DELAY AND LOCAL INTEGRAL CONDITIONS","authors":"Ya. I. Bihun, I. Skutar","doi":"10.31861/bmj2020.02.02","DOIUrl":"https://doi.org/10.31861/bmj2020.02.02","url":null,"abstract":"Multifrequency systems of dierential equations were studied with the help of averaging\u0000method in the works by R.I. Arnold, Ye.O. Grebenikov, Yu.O. Mitropolsky, A.M. Samoilenko\u0000and many other scientists. The complexity of the study of such systems is their inherent resonant\u0000phenomena, which consist in the rational complete or almost complete commensurability of\u0000frequencies. As a result, the solution of the system of equations averaged over fast variables in\u0000the general case may deviate from the solution of the exact problem by the quantity O (1). The\u0000approach to the study of such systems, which was based on the estimation of the corresponding\u0000oscillating integrals, was proposed by A.M. Samoilenko, which allowed to obtain in the works by\u0000A.M. Samoilenko and R.I. Petryshyn a number of important results for multifrequency systems\u0000with initial , boundary and integral conditions.\u0000For multifrequency systems with an argument delay, the averaging method is substantiated\u0000in the works by Ya.Y. Bihun, R.I. Petryshyn, I.V. Krasnokutska and other authors.\u0000In this paper, the averaging method is used to study the solvability of a multifrequency\u0000system with an arbitrary nite number of linearly transformed arguments in slow and fast\u0000variables and integral conditions for slow and fast variables on parts of the interval [0, L] of\u0000the system of equations. An unimproved estimate of the error of the averaging method under\u0000the superimposed conditions is obtained, which clearly depends on the small parameter and\u0000the number of linearly transformed arguments in fast variables.","PeriodicalId":196726,"journal":{"name":"Bukovinian Mathematical Journal","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115917190","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"ON SPLITTING AND STABILITY OF LINEAR STATIONARY SINGULARLY PERTURBED DIFFERENTIAL EQUATIONS","authors":"O. Osypova, I. Cherevko","doi":"10.31861/bmj2019.02.076","DOIUrl":"https://doi.org/10.31861/bmj2019.02.076","url":null,"abstract":"","PeriodicalId":196726,"journal":{"name":"Bukovinian Mathematical Journal","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117097420","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The paper considers the extension of the CMA-ES algorithm using mixtures of distributions for finding optimal hyperparameters of neural networks. Hyperparameter optimization, formulated as the optimization of the black box objective function, which is a necessary condition for automation and high performance of machine learning approaches. CMA-ES is an efficient optimization algorithm without derivatives, one of the alternatives in the combination of hyperparameter optimization methods. The developed algorithm is based on the assumption of a multi-peak density distribution of the parameters of complex systems. Compared to other optimization methods, CMA-ES is computationally inexpensive and supports parallel computations. Research results show that CMA-ES can be competitive, especially in the concurrent assessment mode. However, a much broader and more detailed comparison is still needed, which will include more test tasks and various modifications, such as adding constraints. Based on the Monte Carlo method, it was shown that the new algorithm will improve the search for optimal hyperparameters by an average of 12%.
{"title":"ADVANCED ALGORITHM OF EVOLUTION STRATEGIES OF COVARIATION MATRIX ADAPTATION","authors":"Yu. A. Litvinchuk, I. Malyk","doi":"10.31861/bmj2022.02.09","DOIUrl":"https://doi.org/10.31861/bmj2022.02.09","url":null,"abstract":"The paper considers the extension of the CMA-ES algorithm using mixtures of distributions for finding optimal hyperparameters of neural networks. Hyperparameter optimization, formulated as the optimization of the black box objective function, which is a necessary condition for automation and high performance of machine learning approaches. CMA-ES is an efficient optimization algorithm without derivatives, one of the alternatives in the combination of hyperparameter optimization methods. The developed algorithm is based on the assumption of a multi-peak density distribution of the parameters of complex systems. Compared to other optimization methods, CMA-ES is computationally inexpensive and supports parallel computations. Research results show that CMA-ES can be competitive, especially in the concurrent assessment mode. However, a much broader and more detailed comparison is still needed, which will include more test tasks and various modifications, such as adding constraints. Based on the Monte Carlo method, it was shown that the new algorithm will improve the search for optimal hyperparameters by an average of 12%.","PeriodicalId":196726,"journal":{"name":"Bukovinian Mathematical Journal","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129492930","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In this paper we study topological and metric properties of the set of incomplete sums for positive series $sum {a_k}$, where $a_{2n-1}=3/4^n+3/4^{in}$ and $a_{2n}=2/4^n+2/4^{in}$, $n in N$. The series depends on positive integer parameter $i geq 2$ and it is some perturbation of the known Guthrie-Nymann series. We prove that the set of incomplete sums of this series is a Cantorval (which is a specific union of a perfect nowhere dense set of zero Lebesgue measure and an infinite union of intervals), and its Lebesgue measure is given by formula: $lambda(X^+_i)=1+frac{1}{4^i-3}.$ The main idea of ??proving the theorem is based on the well-known Kakey theorem, the closedness of sets of incomplete sums of the series and the density of the set everywhere in a certain segment. The work provides a full justification of the facts for the case $i=2$. To justify the main facts, the ratio between the members and the remainders of the series is used. For $i=2$ we have $r_0=sum {a_k}=2$, $a_{2n}-r_{2n}= frac{1}{3} cdot frac{1}{4^n} + frac{5}{3} cdot frac{1}{16^n}$ $r_{2n-1}-a_{2n-1}= frac{2}{3} cdot frac{ 1}{4^n}-frac{2}{3} cdot frac{1}{16^n}$. The relevance of the study of the object is dictated by the problems of the geometry of numerical series, fractal analysis and fractal geometry of one-dimensional objects and the theory of infinite Bernoulli convolutions, one of the problems of which is the problem of the singularity of the convolution of two singular distributions.
{"title":"THE SET OF INCOMPLETE SUMS OF THE MODIFIED GUTHRIE-NYMANN SERIES","authors":"M. Pratsiovytyi, D. Karvatsky","doi":"10.31861/bmj2022.02.15","DOIUrl":"https://doi.org/10.31861/bmj2022.02.15","url":null,"abstract":"In this paper we study topological and metric properties of the set of incomplete sums for positive series $sum {a_k}$, where $a_{2n-1}=3/4^n+3/4^{in}$ and $a_{2n}=2/4^n+2/4^{in}$, $n in N$. The series depends on positive integer parameter $i geq 2$ and it is some perturbation of the known Guthrie-Nymann series. We prove that the set of incomplete sums of this series is a Cantorval (which is a specific union of a perfect nowhere dense set of zero Lebesgue measure and an infinite union of intervals), and its Lebesgue measure is given by formula: $lambda(X^+_i)=1+frac{1}{4^i-3}.$ The main idea of ??proving the theorem is based on the well-known Kakey theorem, the closedness of sets of incomplete sums of the series and the density of the set everywhere in a certain segment. The work provides a full justification of the facts for the case $i=2$. To justify the main facts, the ratio between the members and the remainders of the series is used. For $i=2$ we have $r_0=sum {a_k}=2$, $a_{2n}-r_{2n}= frac{1}{3} cdot frac{1}{4^n} + frac{5}{3} cdot frac{1}{16^n}$ $r_{2n-1}-a_{2n-1}= frac{2}{3} cdot frac{ 1}{4^n}-frac{2}{3} cdot frac{1}{16^n}$. The relevance of the study of the object is dictated by the problems of the geometry of numerical series, fractal analysis and fractal geometry of one-dimensional objects and the theory of infinite Bernoulli convolutions, one of the problems of which is the problem of the singularity of the convolution of two singular distributions.","PeriodicalId":196726,"journal":{"name":"Bukovinian Mathematical Journal","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126565689","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Our main result asserts that, under some assumptions, the uniformly-to-order continuity of an order bounded orthogonally additive operator between vector lattices together with its horizontally-to-order continuity implies its order continuity (we say that a mapping f : E → F between vector lattices E and F is horizontally-to-order continuous provided f sends laterally increasing order convergent nets in E to order convergent nets in F, and f is uniformly-to-order continuous provided f sends uniformly convergent nets to order convergent nets).
{"title":"ON SEPARATE ORDER CONTINUITY OF ORTHOGONALLY ADDITIVE OPERATORS","authors":"I. Krasikova, O. Fotiy, M. Pliev, M. Popov","doi":"10.31861/bmj2021.01.17","DOIUrl":"https://doi.org/10.31861/bmj2021.01.17","url":null,"abstract":"Our main result asserts that, under some assumptions, the uniformly-to-order continuity of an order bounded orthogonally additive operator between vector lattices together with its horizontally-to-order continuity implies its order continuity (we say that a mapping f : E → F between vector lattices E and F is horizontally-to-order continuous provided f sends laterally increasing order convergent nets in E to order convergent nets in F, and f is uniformly-to-order continuous provided f sends uniformly convergent nets to order convergent nets).","PeriodicalId":196726,"journal":{"name":"Bukovinian Mathematical Journal","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129147841","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The singular nonsymmetric rank one perturbation of a self-adjoint operator from classes ${mathcal H}_{-1}$ and ${mathcal H}_{-2}$ was considered for the first time in works by Dudkin M.E. and Vdovenko T.I. cite{k8,k9}. In the mentioned papers, some properties of the point spectrum are described, which occur during such perturbations. This paper proposes generalizations of the results presented in cite{k8,k9} and cite{k2} in the case of nonsymmetric class ${mathcal H}_{-2}$ perturbations of finite rank. That is, the formal expression of the following is considered begin{equation*} tilde A=A+sum limits_{j=1}^{n}alpha_jlanglecdot,omega_jrangledelta_j, end{equation*} where $A$ is an unperturbed self-adjoint operator on a separable Hilbert space ${mathcal H}$, $alpha_jin{mathbb C}$, $omega_j$, $delta_j$, $j=1,2, ..., n