{"title":"Simple Proof of the Risk Bound for Denoising by Exponential Weights for Asymmetric Noise Distributions","authors":"A. S. Dalalyan","doi":"10.3103/s106836232306002x","DOIUrl":"https://doi.org/10.3103/s106836232306002x","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>In this note, we consider the problem of aggregation of estimators in order to denoise a signal. The main contribution is a short proof of the fact that the exponentially weighted aggregate satisfies a sharp oracle inequality. While this result was already known for a wide class of symmetric noise distributions, the extension to asymmetric distributions presented in this note is new.</p>","PeriodicalId":54854,"journal":{"name":"Journal of Contemporary Mathematical Analysis-Armenian Academy of Sciences","volume":"30 1","pages":""},"PeriodicalIF":0.3,"publicationDate":"2023-12-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139066425","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Entire Functions and Their High Order Difference Operators","authors":"S. Majumder, N. Sarkar, D. Pramanik","doi":"10.3103/s1068362323060043","DOIUrl":"https://doi.org/10.3103/s1068362323060043","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>In this paper, we prove that for a transcendental entire function <span>(f)</span> of finite order such that <span>(lambda(f-a)<rho(f))</span>, where <span>(a)</span> is an entire function and satisfies <span>(rho(a)<rho(f))</span>, <span>(ninmathbb{N})</span>, if <span>(Delta_{c}^{n}f)</span> and <span>(f)</span> share the entire function <span>(b)</span> satisfying <span>(rho(b)<rho(f))</span> CM, where <span>(cinmathbb{C})</span> satisfies <span>(Delta_{c}^{n}fnotequiv 0)</span>, then <span>(f(z)=a(z)+de^{cz})</span>, where <span>(d,c)</span> are two nonzero constants. In particular, if <span>(a=b)</span>, then <span>(a)</span> reduces to a constant. This result improves and generalizes the recent results of Chen and Chen [3], Liao and Zhang [10] and Lü et al. [11] in a large scale. Also we exhibit some relevant examples to fortify our results.</p>","PeriodicalId":54854,"journal":{"name":"Journal of Contemporary Mathematical Analysis-Armenian Academy of Sciences","volume":"44 4 1","pages":""},"PeriodicalIF":0.3,"publicationDate":"2023-12-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139066477","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"On Khinchin’s Theorem about the Special Role of the Gaussian Distribution","authors":"L. A. Khachatryan","doi":"10.3103/s1068362323060031","DOIUrl":"https://doi.org/10.3103/s1068362323060031","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>The purpose of this note is to recall one remarkable theorem of Khinchin about the special role of the Gaussian distribution. This theorem allows us to give a new interpretation of the Lindeberg condition: it guarantees the uniform integrability of the squares of normed sums of random variables and, thus, the passage to the limit under the expectation sign. The latter provides a simple proof of the central limit theorem for independent random variables.</p>","PeriodicalId":54854,"journal":{"name":"Journal of Contemporary Mathematical Analysis-Armenian Academy of Sciences","volume":"95 1","pages":""},"PeriodicalIF":0.3,"publicationDate":"2023-12-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139066585","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Crossing Malmquist Systems with Certain Types","authors":"F. N. Wang, K. Liu","doi":"10.3103/s1068362323060080","DOIUrl":"https://doi.org/10.3103/s1068362323060080","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>In this paper, we will present the expression of meromorphic solutions on the crossing differential or difference Malmquist systems of certain types using Nevanlinna theory. For instance, we consider the admissible meromorphic solutions of the crossing differential Malmquist system</p><span>$$begin{cases}f^{prime}_{1}(z)=frac{a_{1}(z)f_{2}(z)+a_{0}(z)}{f_{2}(z)+d_{1}(z)}, f^{prime}_{2}(z)=frac{a_{2}(z)f_{1}(z)+b_{0}(z)}{f_{1}(z)+d_{2}(z)},end{cases}$$</span><p>where <span>(a_{1}(z)d_{1}(z)notequiv a_{0}(z))</span> and <span>(a_{2}(z)d_{2}(z)notequiv b_{0}(z))</span>.</p>","PeriodicalId":54854,"journal":{"name":"Journal of Contemporary Mathematical Analysis-Armenian Academy of Sciences","volume":"20 1","pages":""},"PeriodicalIF":0.3,"publicationDate":"2023-12-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139066587","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Convergence of General Fourier Series of Differentiable Functions","authors":"V. Tsagareishvili","doi":"10.3103/s1068362323060067","DOIUrl":"https://doi.org/10.3103/s1068362323060067","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>Convergence of classical Fourier series (trigonometric, Haar, Walsh, <span>(dots)</span> systems) of differentiable functions are trivial problems and they are well known. But general Fourier series, as it is known, even for the function <span>(f(x)=1)</span> does not converge. In such a case, if we want differentiable functions with respect to the general orthonormal system (ONS) <span>((varphi_{n}))</span> to have convergent Fourier series, we must find the special conditions on the functions <span>(varphi_{n})</span> of system <span>((varphi_{n}))</span>. This problem is studied in the present paper. It is established that the resulting conditions are best possible. Subsystems of general orthonormal systems are considered.</p>","PeriodicalId":54854,"journal":{"name":"Journal of Contemporary Mathematical Analysis-Armenian Academy of Sciences","volume":"54 1","pages":""},"PeriodicalIF":0.3,"publicationDate":"2023-12-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139066579","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"A Hardy–Littlewood Type Theorem for Harmonic Bergman–Orlicz Spaces and Applications","authors":"Xi Fu, Q. Shi#","doi":"10.3103/s1068362323050096","DOIUrl":"https://doi.org/10.3103/s1068362323050096","url":null,"abstract":"","PeriodicalId":54854,"journal":{"name":"Journal of Contemporary Mathematical Analysis-Armenian Academy of Sciences","volume":"54 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135963668","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Comparison of Polynomials and Weighted-Hyperbolic Operators","authors":"M. A. Khachaturyan, V. N. Margaryan","doi":"10.3103/s1068362323050023","DOIUrl":"https://doi.org/10.3103/s1068362323050023","url":null,"abstract":"","PeriodicalId":54854,"journal":{"name":"Journal of Contemporary Mathematical Analysis-Armenian Academy of Sciences","volume":"41 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135963494","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Operator Preserving Bernstein-Type Inequalities between Polynomials","authors":"A. Mir, A. Hussain","doi":"10.3103/s1068362323050059","DOIUrl":"https://doi.org/10.3103/s1068362323050059","url":null,"abstract":"","PeriodicalId":54854,"journal":{"name":"Journal of Contemporary Mathematical Analysis-Armenian Academy of Sciences","volume":"121 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135963505","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"On a Generalization of an Operator Preserving Turán-Type Inequality for Complex Polynomials","authors":"S. A. Malik, B. A. Zargar","doi":"10.3103/s1068362323050047","DOIUrl":"https://doi.org/10.3103/s1068362323050047","url":null,"abstract":"Abstract Let $$W(zeta)=(a_{0}+a_{1}zeta+...+a_{n}zeta^{n})$$ be a polynomial of degree $$n$$ having all its zeros in $$mathbb{T}_{k}cupmathbb{E}^{-}_{k}$$ , $$kgeq 1$$ , then for every real or complex number $$alpha$$ with $$|alpha|geq 1+k+k^{n}$$ , Govil and McTume [7] showed that the following inequality holds $$maxlimits_{zetainmathbb{T}_{1}}|D_{alpha}W(zeta)|geq nleft(frac{|alpha|-k}{1+k^{n}}right)||W||+nleft(frac{|alpha|-(1+k+k^{n})}{1+k^{n}}right)minlimits_{zetainmathbb{T}_{k}}|W(zeta)|.$$ In this paper, we have obtained a generalization of this inequality involving sequence of operators known as polar derivatives. In addition, the problem for the limiting case is also considered.","PeriodicalId":54854,"journal":{"name":"Journal of Contemporary Mathematical Analysis-Armenian Academy of Sciences","volume":"11 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135963522","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Distribution of Zeros and Critical Points of a Polynomial, and Sendov’s Conjecture","authors":"G. M. Sofi, W. M. Shah","doi":"10.3103/s1068362323050084","DOIUrl":"https://doi.org/10.3103/s1068362323050084","url":null,"abstract":"Abstract According to the Gauss–Lucas theorem, the critical points of a complex polynomial $$p(z):=sum_{j=0}^{n}a_{j}z^{j}$$ where $$a_{j}inmathbb{C}$$ always lie in the convex hull of its zeros. In this paper, we prove certain relations between the distribution of zeros of a polynomial and its critical points. Using these relations, we prove the well-known Sendov’s conjecture for certain special cases.","PeriodicalId":54854,"journal":{"name":"Journal of Contemporary Mathematical Analysis-Armenian Academy of Sciences","volume":"7 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135963691","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}