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2. Smoothness of Generalized Solutions of the Neumann Problem for a Strongly Elliptic Differential-Difference Equation on the Boundary of Adjacent Subdomains
- Author
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D. A. Neverova
- Subjects
Statistics and Probability ,Smoothness (probability theory) ,Applied Mathematics ,General Mathematics ,Mathematical analysis ,Neumann boundary condition ,Boundary (topology) ,Differential difference equations ,General Medicine ,Mathematics - Abstract
This paper is devoted to the study of the qualitative properties of solutions to boundary-value problems for strongly elliptic differential-difference equations. Some results for these equations such as existence and smoothness of generalized solutions in certain subdomains of Q were obtained earlier. Nevertheless, the smoothness of generalized solutions of such problems can be violated near the boundary of these subdomains even for infinitely differentiable right-hand side. The subdomains are defined as connected components of the set that is obtained from the domain Q by throwing out all possible shifts of the boundary Q by vectors of a certain group generated by shifts occurring in the difference operators. For the one dimensional Neumann problem for differential-difference equations there were obtained conditions on the coefficients of difference operators, under which for any continuous right-hand side there is a classical solution of the problem that coincides with the generalized solution. 2 Also there was obtained the smoothness (in Sobolev spaces W k ) of generalized solutions of the second and the third boundary-value problems for strongly elliptic differential-difference equations in subdomains excluding -neighborhoods of certain points. However, the smoothness (in Ho lder spaces) of generalized solutions of the second boundary-value problem for strongly elliptic differential-difference equations on the boundary of adjacent subdomains was not considered. In this paper, we study this question in Ho lder spaces. We establish necessary and sufficient conditions for the coefficients of difference operators that guarantee smoothness of the generalized solution on the boundary of adjacent subdomains for any right-hand side from the Ho lder space.
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- 2022
3. The geometry of diagonal groups
- Author
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Peter J. Cameron, Cheryl E. Praeger, Csaba Schneider, R. A. Bailey, University of St Andrews. Pure Mathematics, University of St Andrews. Centre for Interdisciplinary Research in Computational Algebra, and University of St Andrews. Statistics
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Mathematics(all) ,South china ,Primitive permutation group ,General Mathematics ,Diagonal group ,T-NDAS ,Library science ,Group Theory (math.GR) ,O'Nan-Scott Theorem ,01 natural sciences ,Hospitality ,FOS: Mathematics ,NCAD ,Mathematics - Combinatorics ,QA Mathematics ,0101 mathematics ,Diagonal semilattice ,QA ,Cartesian lattice ,Mathematics ,business.industry ,20B05 ,Applied Mathematics ,010102 general mathematics ,Latin square ,Semilattice ,Latin cube ,010101 applied mathematics ,Hamming graph ,Research council ,Diagonal graph ,Combinatorics (math.CO) ,business ,Mathematics - Group Theory ,Partition - Abstract
Part of the work was done while the authors were visiting the South China University of Science and Technology (SUSTech), Shenzhen, in 2018, and we are grateful (in particular to Professor Cai Heng Li) for the hospitality that we received.The authors would like to thank the Isaac Newton Institute for Mathematical Sciences, Cambridge, for support and hospitality during the programme Groups, representations and applications: new perspectives (supported by EPSRC grant no.EP/R014604/1), where further work on this paper was undertaken. In particular we acknowledge a Simons Fellowship (Cameron) and a Kirk Distinguished Visiting Fellowship (Praeger) during this programme. Schneider thanks the Centre for the Mathematics of Symmetry and Computation of The University of Western Australia and Australian Research Council Discovery Grant DP160102323 for hosting his visit in 2017 and acknowledges the support of the CNPq projects Produtividade em Pesquisa (project no.: 308212/2019-3) and Universal (project no.:421624/2018-3). Diagonal groups are one of the classes of finite primitive permutation groups occurring in the conclusion of the O'Nan-Scott theorem. Several of the other classes have been described as the automorphism groups of geometric or combinatorial structures such as affine spaces or Cartesian decompositions, but such structures for diagonal groups have not been studied in general. The main purpose of this paper is to describe and characterise such structures, which we call diagonal semilattices. Unlike the diagonal groups in the O'Nan-Scott theorem, which are defined over finite characteristically simple groups, our construction works over arbitrary groups, finite or infinite. A diagonal semilattice depends on a dimension m and a group T. For m=2, it is a Latin square, the Cayley table of T, though in fact any Latin square satisfies our combinatorial axioms. However, for m≥3, the group T emerges naturally and uniquely from the axioms. (The situation somewhat resembles projective geometry, where projective planes exist in great profusion but higher-dimensional structures are coordinatised by an algebraic object, a division ring.) A diagonal semilattice is contained in the partition lattice on a set Ω, and we provide an introduction to the calculus of partitions. Many of the concepts and constructions come from experimental design in statistics. We also determine when a diagonal group can be primitive, or quasiprimitive (these conditions turn out to be equivalent for diagonal groups). Associated with the diagonal semilattice is a graph, the diagonal graph, which has the same automorphism group as the diagonal semilattice except in four small cases with m
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- 2022
4. On the geometry of irreversible metric-measure spaces: Convergence, stability and analytic aspects
- Author
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Wei Zhao and Alexandru Kristály
- Subjects
Pure mathematics ,Class (set theory) ,Applied Mathematics ,General Mathematics ,Stability (learning theory) ,Function (mathematics) ,Stability result ,Measure (mathematics) ,Metric (mathematics) ,Convergence (routing) ,Mathematics::Metric Geometry ,Mathematics::Differential Geometry ,Topology (chemistry) ,Mathematics - Abstract
The paper is devoted to the study of Gromov-Hausdorff convergence and stability of irreversible metric-measure spaces, both in the compact and noncompact cases. While the compact setting is mostly similar to the reversible case developed by J. Lott, K.-T. Sturm and C. Villani, the noncompact case provides various surprising phenomena. Since the reversibility of noncompact irreversible spaces might be infinite, it is motivated to introduce a suitable nondecreasing function that bounds the reversibility of larger and larger balls. By this approach, we are able to prove satisfactory convergence/stability results in a suitable – reversibility depending – Gromov-Hausdorff topology. A wide class of irreversible spaces is provided by Finsler manifolds, which serve to construct various model examples by pointing out genuine differences between the reversible and irreversible settings. We conclude the paper by proving various geometric and functional inequalities (as Brunn-Minkowski, Bishop-Gromov, log-Sobolev and Lichnerowicz inequalities) on irreversible structures.
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- 2022
5. On the general strong fuzzy solutions of general fuzzy matrix equation involving the Core-EP inverse
- Author
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Caijing Jiang, Xiaoji Liu, and Hongjie Jiang
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General Mathematics ,MathematicsofComputing_NUMERICALANALYSIS ,general strong fuzzy solution ,Inverse ,Fuzzy logic ,unique least squares solution ,Fuzzy matrix ,Core (graph theory) ,QA1-939 ,core-ep inverse ,Applied mathematics ,fuzzy linear systems ,Mathematics - Abstract
The inconsistent or consistent general fuzzy matrix equation are studied in this paper. The aim of this paper is threefold. Firstly, general strong fuzzy matrix solutions of consistent general fuzzy matrix equation are derived, and an algorithm for obtaining general strong fuzzy solutions of general fuzzy matrix equation by Core-EP inverse is also established. Secondly, if inconsistent or consistent general fuzzy matrix equation satisfies $ X\in R(S^{k}) $, the unique solution or unique least squares solution of consistent or inconsistent general fuzzy matrix equation are given by Core-EP inverse. Thirdly, we present an algorithm for obtaining Core-EP inverse. Finally, we present some examples to illustrate the main results.
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- 2022
6. Improved structural methods for nonlinear differential-algebraic equations via combinatorial relaxation
- Author
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Taihei Oki
- Subjects
Computer Science - Symbolic Computation ,FOS: Computer and information sciences ,Dynamical systems theory ,General Mathematics ,Mathematics::Optimization and Control ,010103 numerical & computational mathematics ,0102 computer and information sciences ,Symbolic Computation (cs.SC) ,01 natural sciences ,Computer Science::Systems and Control ,ComputingMethodologies_SYMBOLICANDALGEBRAICMANIPULATION ,FOS: Mathematics ,Applied mathematics ,Computer Science::Symbolic Computation ,Mathematics - Numerical Analysis ,0101 mathematics ,Mathematics - Optimization and Control ,Mathematics ,Numerical analysis ,Applied Mathematics ,Relaxation (iterative method) ,Numerical Analysis (math.NA) ,Solver ,Numerical integration ,Nonlinear system ,Computational Mathematics ,Optimization and Control (math.OC) ,010201 computation theory & mathematics ,Differential algebraic equation ,Equation solving - Abstract
Differential-algebraic equations (DAEs) are widely used for modeling of dynamical systems. In numerical analysis of DAEs, consistent initialization and index reduction are important preprocessing prior to numerical integration. Existing DAE solvers commonly adopt structural preprocessing methods based on combinatorial optimization. Unfortunately, the structural methods fail if the DAE has numerical or symbolic cancellations. For such DAEs, methods have been proposed to modify them to other DAEs to which the structural methods are applicable, based on the combinatorial relaxation technique. Existing modification methods, however, work only for a class of DAEs that are linear or close to linear. This paper presents two new modification methods for nonlinear DAEs: the substitution method and the augmentation method. Both methods are based on the combinatorial relaxation approach and are applicable to a large class of nonlinear DAEs. The substitution method symbolically solves equations for some derivatives based on the implicit function theorem and substitutes the solution back into the system. Instead of solving equations, the augmentation method modifies DAEs by appending new variables and equations. The augmentation method has advantages that the equation solving is not needed and the sparsity of DAEs is retained. It is shown in numerical experiments that both methods, especially the augmentation method, successfully modify high-index DAEs that the DAE solver in MATLAB cannot handle., Comment: A preliminary version of this paper is to appear in Proceedings of the 44th International Symposium on Symbolic and Algebraic Computation (ISSAC 2019), Beijing, China, July 2019
- Published
- 2021
7. Covering by homothets and illuminating convex bodies
- Author
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Alexey Glazyrin
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Conjecture ,Applied Mathematics ,General Mathematics ,Discrete geometry ,Boundary (topology) ,Metric Geometry (math.MG) ,Upper and lower bounds ,Infimum and supremum ,Homothetic transformation ,Combinatorics ,Mathematics - Metric Geometry ,Hausdorff dimension ,FOS: Mathematics ,Mathematics::Metric Geometry ,Convex body ,Mathematics - Abstract
The paper is devoted to coverings by translative homothets and illuminations of convex bodies. For a given positive number $\alpha$ and a convex body $B$, $g_{\alpha}(B)$ is the infimum of $\alpha$-powers of finitely many homothety coefficients less than 1 such that there is a covering of $B$ by translative homothets with these coefficients. $h_{\alpha}(B)$ is the minimal number of directions such that the boundary of $B$ can be illuminated by this number of directions except for a subset whose Hausdorff dimension is less than $\alpha$. In this paper, we prove that $g_{\alpha}(B)\leq h_{\alpha}(B)$, find upper and lower bounds for both numbers, and discuss several general conjectures. In particular, we show that $h_{\alpha} (B) > 2^{d-\alpha}$ for almost all $\alpha$ and $d$ when $B$ is the $d$-dimensional cube, thus disproving the conjecture from Research Problems in Discrete Geometry by Brass, Moser, and Pach.
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- 2021
8. Unique Continuation at the Boundary for Harmonic Functions in C 1 Domains and Lipschitz Domains with Small Constant
- Author
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Xavier Tolsa
- Subjects
Surface (mathematics) ,Pure mathematics ,Applied Mathematics ,General Mathematics ,Mathematics::Analysis of PDEs ,Boundary (topology) ,Lipschitz continuity ,Measure (mathematics) ,Domain (mathematical analysis) ,Mathematics - Analysis of PDEs ,Harmonic function ,Lipschitz domain ,Mathematics - Classical Analysis and ODEs ,Classical Analysis and ODEs (math.CA) ,FOS: Mathematics ,Constant (mathematics) ,31B05 31B20 ,Analysis of PDEs (math.AP) ,Mathematics - Abstract
Let $\Omega\subset\mathbb R^n$ be a $C^1$ domain, or more generally, a Lipschitz domain with small local Lipschitz constant. In this paper it is shown that if $u$ is a function harmonic in $\Omega$ and continuous in $\overline \Omega$ which vanishes in a relatively open subset $\Sigma\subset\partial\Omega$ and moreover the normal derivative $\partial_\nu u$ vanishes in a subset of $\Sigma$ with positive surface measure, then $u$ is identically $0$., Comment: More detailed explanation in some argument involving integration by parts and in Remark 3.3. An additional appendix with a self-contained proof of Lemma 4.3, whose proof was not included in the paper previously
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- 2021
9. Strong convergence algorithm for the split problem of variational inclusions, split generalized equilibrium problem and fixed point problem
- Author
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Mubashshir Uddin Khairoowala, Mohd Asad, and Shamshad Husain
- Subjects
Fixed point problem ,General Mathematics ,Scheme (mathematics) ,Convergence (routing) ,Solution set ,Applied mathematics ,Common element ,Equilibrium problem ,Mathematics - Abstract
The purpose of this paper is to recommend an iterative scheme to approximate a common element of the solution sets of the split problem of variational inclusions, split generalized equilibrium problem and fixed point problem for non-expansive mappings. We prove that the sequences generated by the recommended iterative scheme strongly converge to a common element of solution sets of stated split problems. In the end, we provide a numerical example to support and justify our main result. The result studied in this paper generalizes and extends some widely recognized results in this direction.
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- 2021
10. Aspherical manifolds, Mellin transformation and a question of Bobadilla–Kollár
- Author
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Yongqiang Liu, Botong Wang, and Laurenţiu G. Maxim
- Subjects
Mathematics - Algebraic Geometry ,Pure mathematics ,Transformation (function) ,Applied Mathematics ,General Mathematics ,14F05, 14F35, 14F45, 32S60, 32L05, 58K15 ,Mathematics - Algebraic Topology ,Mathematics - Abstract
In their 2012 paper, Bobadilla and Koll\'ar studied topological conditions which guarantee that a proper map of complex algebraic varieties is a topological or differentiable fibration. They also asked whether a certain finiteness property on the relative covering space can imply that a proper map is a fibration. In this paper, we answer positively the integral homology version of their question in the case of abelian varieties, and the rational homology version in the case of compact ball quotients. We also propose several conjectures in relation to the Singer-Hopf conjecture in the complex projective setting., Comment: published/final version
- Published
- 2021
11. On one generalization of the Hermite quadrature formula
- Author
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Y. V. Dirvuk, Y. A. Rouba, and K. A. Smatrytski
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Computational Theory and Mathematics ,Generalization ,General Mathematics ,General Physics and Astronomy ,Applied mathematics ,Gauss–Hermite quadrature ,Mathematics - Abstract
In this paper we propose a new approach to the construction of quadrature formulas of interpolation rational type on an interval. In the introduction, a brief analysis of the results on the topic of the research is carried out. Most attention is paid to the works of mathematicians of the Belarusian school on approximation theory – Gauss, Lobatto, and Radau quadrature formulas with nodes at the zeros of the rational Chebyshev – Markov fractions. Rational fractions on the segment, generalizing the classical orthogonal Jacobi polynomials with one weight, are defined, and some of their properties are described. One of the main results of this paper consists in constructing quadrature formulas with nodes at zeros of the introduced rational fractions, calculating their coefficients in an explicit form, and estimating the remainder. This result is preceded by some auxiliary statements describing the properties of special rational functions. Classical methods of mathematical analysis, approximation theory, and the theory of functions of a complex variable are used for proof. In the conclusion a numerical analysis of the efficiency of the constructed quadrature formulas is carried out. Meanwhile, the choice of the parameters on which the nodes of the quadrature formulas depend is made in several standard ways. The obtained results can be applied for further research of rational quadrature formulas, as well as in numerical analysis.
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- 2021
12. Chaotic behavior of the p-adic Potts–Bethe mapping II
- Author
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Otabek Khakimov and Farrukh Mukhamedov
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Pure mathematics ,Applied Mathematics ,General Mathematics ,ComputingMethodologies_DOCUMENTANDTEXTPROCESSING ,Chaotic ,Mathematics - Abstract
The renormalization group method has been developed to investigate p-adic q-state Potts models on the Cayley tree of order k. This method is closely related to the examination of dynamical behavior of the p-adic Potts–Bethe mapping which depends on the parameters q, k. In Mukhamedov and Khakimov [Chaotic behavior of the p-adic Potts–Behte mapping. Discrete Contin. Dyn. Syst.38 (2018), 231–245], we have considered the case when q is not divisible by p and, under some conditions, it was established that the mapping is conjugate to the full shift on $\kappa _p$ symbols (here $\kappa _p$ is the greatest common factor of k and $p-1$ ). The present paper is a continuation of the forementioned paper, but here we investigate the case when q is divisible by p and k is arbitrary. We are able to fully describe the dynamical behavior of the p-adic Potts–Bethe mapping by means of a Markov partition. Moreover, the existence of a Julia set is established, over which the mapping exhibits a chaotic behavior. We point out that a similar result is not known in the case of real numbers (with rigorous proofs).
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- 2021
13. Stress-Strength Parameter Estimation under Small Sample Size: A Testing Hypothesis Approach
- Author
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Hassan Alsuhabi, M. M. Abd El-Raouf, and Mohammad Mehdi Saber
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Likelihood Functions ,Article Subject ,General Computer Science ,Estimation theory ,General Mathematics ,General Neuroscience ,Computer applications to medicine. Medical informatics ,R858-859.7 ,Inference ,Asymptotic distribution ,Estimator ,Neurosciences. Biological psychiatry. Neuropsychiatry ,Small sample ,General Medicine ,Confidence interval ,Exponential function ,Distribution (mathematics) ,Research Design ,Sample Size ,Applied mathematics ,RC321-571 ,Research Article ,Mathematics - Abstract
In this paper, uniformly most powerful unbiased test for testing the stress-strength model has been presented for the first time. The end of the paper is recommending a method which is appropriate for no large data where a normal asymptotic distribution is not applicable. The previous methods for inference on stress-strength models use almost all the asymptotic properties of maximum likelihood estimators. The distribution of components is considered exponential and generalized logistic. A corresponding unbiased confidence interval is constructed, too. We compare presented methodology with previous methods and show the method of this paper is logically better than other methods. Interesting result is that our recommended method not only uses from small sample size but also has better result than other ones.
- Published
- 2021
14. On the minimum value of the condition number of polynomials
- Author
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Carlos Beltrán, Fátima Lizarte, and Universidad de Cantabria
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Sequence ,Degree (graph theory) ,Mathematics - Complex Variables ,Applied Mathematics ,General Mathematics ,Univariate ,Term (logic) ,Combinatorics ,Computational Mathematics ,Integer ,Simple (abstract algebra) ,FOS: Mathematics ,30E10, 30C15, 31A15 ,Complex Variables (math.CV) ,Constant (mathematics) ,Condition number ,Mathematics - Abstract
In 1993, Shub and Smale posed the problem of finding a sequence of univariate polynomials of degree $N$ with condition number bounded above by $N$. In a previous paper by C. Belt\'an, U. Etayo, J. Marzo and J. Ortega-Cerd\`a, it was proved that the optimal value of the condition number is of the form $O(\sqrt{N})$, and the sequence demanded by Shub and Smale was described by a closed formula (for large enough $N\geqslant N_0$ with $N_0$ unknown) and by a search algorithm for the rest of the cases. In this paper we find concrete estimates for the constant hidden in the $O(\sqrt{N})$ term and we describe a simple formula for a sequence of polynomials whose condition number is at most $N$, valid for all $N=4M^2$, with $M$ a positive integer., Comment: 21 pages
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- 2021
15. On the Baum–Connes conjecture for discrete quantum groups with torsion and the quantum Rosenberg conjecture
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Adam Skalski and Yuki Arano
- Subjects
Pure mathematics ,Conjecture ,Mathematics::Operator Algebras ,Quantum group ,Applied Mathematics ,General Mathematics ,Mathematics - Operator Algebras ,Crossed product ,Unimodular matrix ,Mathematics::K-Theory and Homology ,Primary 46L67, Secondary 46L80 ,FOS: Mathematics ,Baum–Connes conjecture ,Countable set ,Equivariant map ,Operator Algebras (math.OA) ,Quantum ,Mathematics - Abstract
We give a decomposition of the equivariant Kasparov category for discrete quantum group with torsions. As an outcome, we show that the crossed product by a discrete quantum group in a certain class preserves the UCT. We then show that quasidiagonality of a reduced C*-algebra of a countable discrete quantum group $\Gamma$ implies that $\Gamma$ is amenable, and deduce from the work of Tikuisis, White and Winter, and the results in the first part of the paper, the converse (i.e. the quantum Rosenberg Conjecture) for a large class of countable discrete unimodular quantum groups. We also note that the unimodularity is a necessary condition., Comment: 15 pages, v2 corrects a few minor points. The final version of the paper will appear in the Proceedings of the American Mathematical Society
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- 2021
16. Splines of the Fourth Order Approximation and the Volterra Integral Equations
- Author
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D.E. Zhilin, A.G. Doronina, and I. G. Burova
- Subjects
Polynomial ,Series (mathematics) ,General Mathematics ,Type (model theory) ,Integral equation ,Volterra integral equation ,symbols.namesake ,Continuation ,Computer Science::Graphics ,symbols ,Applied mathematics ,Focus (optics) ,Mathematics ,Interpolation - Abstract
This paper is a continuation of a series of papers devoted to the numerical solution of integral equations using local interpolation splines. The main focus is given to the use of splines of the fourth order of approximation. The features of the application of the polynomial and non-polynomial splines of the fourth order of approximation to the solution of Volterra integral equation of the second kind are discussed. In addition to local splines of the Lagrangian type, integro-differential splines are also used to construct computational schemes. The comparison of the solutions obtained by different methods is carried out. The results of the numerical experiments are presented.
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- 2021
17. The nilpotent cone for classical Lie superalgebras
- Author
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Daniel K. Nakano and L. Jenkins
- Subjects
Pure mathematics ,Nilpotent cone ,17B20, 17B10 ,Applied Mathematics ,General Mathematics ,Group Theory (math.GR) ,Representation theory ,Mathematics::Quantum Algebra ,FOS: Mathematics ,Representation Theory (math.RT) ,Mathematics::Representation Theory ,Mathematics - Group Theory ,Mathematics - Representation Theory ,Mathematics - Abstract
In this paper the authors introduce an analogue of the nilpotent cone, N {\mathcal N} , for a classical Lie superalgebra, g {\mathfrak g} , that generalizes the definition for the nilpotent cone for semisimple Lie algebras. For a classical simple Lie superalgebra, g = g 0 ¯ ⊕ g 1 ¯ {\mathfrak g}={\mathfrak g}_{\bar 0}\oplus {\mathfrak g}_{\bar 1} with Lie G 0 ¯ = g 0 ¯ \text {Lie }G_{\bar 0}={\mathfrak g}_{\bar 0} , it is shown that there are finitely many G 0 ¯ G_{\bar 0} -orbits on N {\mathcal N} . Later the authors prove that the Duflo-Serganova commuting variety, X {\mathcal X} , is contained in N {\mathcal N} for any classical simple Lie superalgebra. Consequently, our finiteness result generalizes and extends the work of Duflo-Serganova on the commuting variety. Further applications are given at the end of the paper.
- Published
- 2021
18. Infinite-dimensional stochastic differential equations and tail $\sigma$-fields II: the IFC condition
- Author
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Hirofumi Osada, Hideki Tanemura, and Yosuke Kawamoto
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General Mathematics ,Weak solution ,Universality (philosophy) ,Dirichlet distribution ,Symmetry (physics) ,Primary 60K35, Secondary 60H10, 82C22, 60B20 ,symbols.namesake ,Stochastic differential equation ,symbols ,Applied mathematics ,Uniqueness ,Random matrix ,Mathematics - Probability ,Brownian motion ,Computer Science::Information Theory ,Mathematics - Abstract
In a previous report, the second and third authors gave general theorems for unique strong solutions of infinite-dimensional stochastic differential equations (ISDEs) describing the dynamics of infinitely many interacting Brownian particles. One of the critical assumptions is the \lq\lq IFC" condition. The IFC condition requires that, for a given weak solution, the scheme consisting of the finite-dimensional stochastic differential equations (SDEs) related to the ISDEs exists. Furthermore, the IFC condition implies that each finite-dimensional SDE has unique strong solutions. Unlike other assumptions, the IFC condition is challenging to verify, and so the previous report only verified solution for solutions given by quasi-regular Dirichlet forms. In the present paper, we provide a sufficient condition for the IFC requirement in more general situations. In particular, we prove the IFC condition without assuming the quasi-regularity or symmetry of the associated Dirichlet forms. As an application of the theoretical formulation, the results derived in this paper are used to prove the uniqueness of Dirichlet forms and the dynamical universality of random matrices., Comment: This paper is a continuation of "Infinite-dimensional stochastic differential equations and tail $\sigma $-fields", which published in Probability Theory and Related Fields, https://doi.org/10.1007/s00440-020-00981-y. This paper will be published in Journal of the Mathematical Society of Japan
- Published
- 2022
19. Minimization arguments in analysis of variational-hemivariational inequalities
- Author
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Weimin Han and Mircea Sofonea
- Subjects
Applied Mathematics ,General Mathematics ,Hilbert space ,Structure (category theory) ,General Physics and Astronomy ,Contrast (statistics) ,010103 numerical & computational mathematics ,Fixed point ,01 natural sciences ,010101 applied mathematics ,Nonlinear system ,symbols.namesake ,Contact mechanics ,Compact space ,symbols ,Applied mathematics ,Minification ,0101 mathematics ,Mathematics - Abstract
In this paper, an alternative approach is provided in the well-posedness analysis of elliptic variational–hemivariational inequalities in real Hilbert spaces. This includes the unique solvability and continuous dependence of the solution on the data. In most of the existing literature on elliptic variational–hemivariational inequalities, well-posedness results are obtained by using arguments of surjectivity for pseudomonotone multivalued operators, combined with additional compactness and pseudomonotonicity properties. In contrast, following (Han in Nonlinear Anal B Real World Appl 54:103114, 2020; Han in Numer Funct Anal Optim 42:371–395, 2021), the approach adopted in this paper is based on the fixed point structure of the problems, combined with minimization principles for elliptic variational–hemivariational inequalities. Consequently, only elementary results of functional analysis are needed in the approach, which makes the theory of elliptic variational–hemivariational inequalities more accessible to applied mathematicians and engineers. The theoretical results are illustrated on a representative example from contact mechanics.
- Published
- 2022
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20. Optimality Conditions Using Convexifactors for a Multiobjective Fractional Bilevel Programming Problem
- Author
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Bhawna Kohli
- Subjects
Mathematical optimization ,Applied Mathematics ,General Mathematics ,Bilevel optimization ,Mathematics - Abstract
In this paper, a multiobjective fractional bilevel programming problem is considered and optimality conditions using the concept of convexifactors are established for it. For this purpose, a suitable constraint qualification in terms of convexifactors is introduced for the problem. Further in the paper, notions of asymptotic pseudoconvexity, asymptotic quasiconvexity in terms of convexifactors are given and using them sufficient optimality conditions are derived.
- Published
- 2021
21. Convergence Theorems for Suzuki Generalized Nonexpansive Mapping in Banach Spaces
- Author
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Seyit Temir and Abdulhamit Ekinci
- Subjects
Pure mathematics ,Applied Mathematics ,General Mathematics ,Banach space ,Convergence (relationship) ,Mathematics - Abstract
In this paper, we study a new iterative scheme to approximate fixed point of Suzuki nonexpansive type mappings in Banach space. We also provesome weak and strong theorems for Suzuki nonexpansive typemappings. Numerical example is given to show the efficiency of newiteration process. The results obtained in this paper improve therecent ones announced by B. S. Thakur et al. \cite{Thakur}, Ullahand Arschad \cite{UA}.
- Published
- 2021
22. On the relation of the spectral test to isotropic discrepancy and L-approximation in Sobolev spaces
- Author
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Mathias Sonnleitner and Friedrich Pillichshammer
- Subjects
Statistics and Probability ,Numerical Analysis ,Control and Optimization ,Algebra and Number Theory ,Applied Mathematics ,General Mathematics ,010102 general mathematics ,Isotropy ,Mathematical analysis ,Convex set ,Boundary (topology) ,010103 numerical & computational mathematics ,01 natural sciences ,Upper and lower bounds ,Spectral test ,Sobolev space ,Dimension (vector space) ,Unit cube ,0101 mathematics ,Mathematics - Abstract
This paper is a follow-up to the recent paper of Pillichshammer and Sonnleitner (2020) [12] . We show that the isotropic discrepancy of a lattice point set is at most d 2 2 ( d + 1 ) times its spectral test, thereby correcting the dependence on the dimension d and an inaccuracy in the proof of the upper bound in Theorem 2 of the mentioned paper. The major task is to bound the volume of the neighbourhood of the boundary of a convex set contained in the unit cube. Further, we characterize averages of the distance to a lattice point set in terms of the spectral test. As an application, we infer that the spectral test – and with it the isotropic discrepancy – is crucial for the suitability of the lattice point set for the approximation of Sobolev functions.
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- 2021
23. Hermite B-Splines: n-Refinability and Mask Factorization
- Author
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Caroline Moosmüller and Mariantonia Cotronei
- Subjects
Monomial ,Polynomial ,Hermite polynomials ,General Mathematics ,subdivision schemes ,Mathematics::Classical Analysis and ODEs ,Basis function ,Context (language use) ,polynomial reproduction ,Hermite splines ,Annihilator ,Operator (computer programming) ,Factorization ,QA1-939 ,Computer Science (miscellaneous) ,Applied mathematics ,Engineering (miscellaneous) ,Mathematics ,spectral condition - Abstract
This paper deals with polynomial Hermite splines. In the first part, we provide a simple and fast procedure to compute the refinement mask of the Hermite B-splines of any order and in the case of a general scaling factor. Our procedure is solely derived from the polynomial reproduction properties satisfied by Hermite splines and it does not require the explicit construction or evaluation of the basis functions. The second part of the paper discusses the factorization properties of the Hermite B-spline masks in terms of the augmented Taylor operator, which is shown to be the minimal annihilator for the space of discrete monomial Hermite sequences of a fixed degree. All our results can be of use, in particular, in the context of Hermite subdivision schemes and multi-wavelets.
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- 2021
24. Optimal Control Problems Involving Combined Fractional Operators with General Analytic Kernels
- Author
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Delfim F. M. Torres and Faïçal Ndaïrou
- Subjects
Fractional operators with general analytic kernels ,Class (set theory) ,Mangasarian sufficient optimality condition ,General Mathematics ,optimal control and Pontryagin’s extremals ,26A33, 49K15 ,fractional operators with general analytic kernels ,Type inequality ,Type (model theory) ,Optimal control ,Pontryagin's minimum principle ,Optimization and Control (math.OC) ,Gronwall's inequality ,Kernel (statistics) ,Gronwall’s inequality ,FOS: Mathematics ,QA1-939 ,Computer Science (miscellaneous) ,Applied mathematics ,Differentiable function ,Mathematics - Optimization and Control ,Engineering (miscellaneous) ,Optimal control and Pontryagin’s extremals ,Mathematics - Abstract
Fractional optimal control problems via a wide class of fractional operators with a general analytic kernel are introduced. Necessary optimality conditions of Pontryagin type for the considered problem are obtained after proving a Gronwall type inequality as well as results on continuity and differentiability of perturbed trajectories. Moreover, a Mangasarian type sufficient global optimality condition for the general analytic kernel fractional optimal control problem is proved. An illustrative example is discussed., Comment: This is a preprint of a paper whose final and definite form is published Open Access in 'Mathematics', at [https://doi.org/10.3390/math9192355]. Cite this paper as: F. Nda\"{\i}rou and D.F.M. Torres, Optimal control problems involving combined fractional operators with general analytic kernels, Mathematics 9 (2021), no. 19, Art. 2355, 17 pp
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- 2021
25. Analytic Detection in Homotopy Groups of Smooth Manifolds
- Author
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I. S. Zubov
- Subjects
Statistics and Probability ,Pure mathematics ,Fundamental group ,Homotopy group ,Riemann surface ,Applied Mathematics ,General Mathematics ,Holomorphic function ,General Medicine ,Central series ,Hopf invariant ,symbols.namesake ,Linear differential equation ,symbols ,Element (category theory) ,Mathematics - Abstract
In this paper, for the mapping of a sphere into a compact orientable manifold S n → M , n ⩾ 1 , we solve the problem of determining whether it represents a nontrivial element in the homotopy group of the manifold π n ( M ) πn(M ). For this purpose, we consistently use the theory of iterated integrals developed by K.-T. Chen. It should be noted that the iterated integrals as repeated integration were previously meaningfully used by Lappo-Danilevsky to represent solutions of systems of linear differential equations and by Whitehead for the analytical description of the Hopf invariant for mappings f : S 2 n - 1 → S n , n ⩾ 2 . We give a brief description of Chen’s theory, representing Whitehead’s and Haefliger’s formulas for the Hopf invariant and generalized Hopf invariant. Examples of calculating these invariants using the technique of iterated integrals are given. Further, it is shown how one can detect any element of the fundamental group of a Riemann surface using iterated integrals of holomorphic forms. This required to prove that the intersection of the terms of the lower central series of the fundamental group of a Riemann surface is a unit group.
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- 2022
26. On Initial-Boundary Value Problem on Semiaxis for Generalized Kawahara Equation
- Author
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A. V. Faminskii and E. V. Martynov
- Subjects
Statistics and Probability ,media_common.quotation_subject ,Applied Mathematics ,General Mathematics ,General Medicine ,Infinity ,Term (time) ,Nonlinear system ,Applied mathematics ,Boundary value problem ,Uniqueness ,Value (mathematics) ,Mathematics ,media_common - Abstract
In this paper, we consider initial-boundary value problem on semiaxis for generalized Kawahara equation with higher-order nonlinearity. We obtain the result on existence and uniqueness of the global solution. Also, if the equation contains the absorbing term vanishing at infinity, we prove that the solution decays at large time values.
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- 2022
27. On Spectral and Evolutional Problems Generated by a Sesquilinear Form
- Author
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A. R. Yakubova
- Subjects
Statistics and Probability ,Pure mathematics ,Sesquilinear form ,Applied Mathematics ,General Mathematics ,General Medicine ,Mathematics - Abstract
On the base of boundary-value, spectral and initial-boundary value problems studied earlier for the case of single domain, we consider corresponding problems generated by sesquilinear form for two domains. Arising operator pencils with corresponding operator coefficients acting in a Hilbert space and depending on two parameters are studied in detail. In the perturbed and unperturbed cases, we consider two situations when one of the parameters is spectral and the other is fixed. In this paper, we use the superposition principle that allow us to present the solution of the original problem as a sum of solutions of auxiliary boundary-value problems containing inhomogeneity either in the equation or in one of the boundary conditions. The necessary and sufficient conditions for the correct solvability of boundary-value problems on given time interval are obtained. The theorems on properties of the spectrum and on the completeness and basicity of the system of root elements are proved.
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- 2022
28. Multiplication of Distributions and Algebras of Mnemofunctions
- Author
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A B Antonevich and T G Shagova
- Subjects
Statistics and Probability ,Classical theory ,Pure mathematics ,Distribution (mathematics) ,General method ,Operator (physics) ,Applied Mathematics ,General Mathematics ,Embedding ,Multiplication ,General Medicine ,Space (mathematics) ,Mathematics - Abstract
In this paper, we discuss methods and approaches for definition of multiplication of distributions, which is not defined in general in the classical theory. We show that this problem is related to the fact that the operator of multiplication by a smooth function is nonclosable in the space of distributions. We give the general method of construction of new objects called new distributions, or mnemofunctions, that preserve essential properties of usual distributions and produce algebras as well. We describe various methods of embedding of distribution spaces into algebras of mnemofunctions. All ideas and considerations are illustrated by the simplest example of the distribution space on a circle. Some effects arising in study of equations with distributions as coefficients are demonstrated by example of a linear first-order differential equation.
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- 2022
29. Asymptotic Properties of Stationary Solutions of Coupled Nonconvex Nonsmooth Empirical Risk Minimization
- Author
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Zhengling Qi, Jong-Shi Pang, Yufeng Liu, and Ying Cui
- Subjects
Class (set theory) ,Consistency (statistics) ,General Mathematics ,Convergence (routing) ,Applied mathematics ,Asymptotic distribution ,Statistical analysis ,Empirical risk minimization ,Management Science and Operations Research ,Computer Science Applications ,Mathematics - Abstract
This paper has two main goals: (a) establish several statistical properties—consistency, asymptotic distributions, and convergence rates—of stationary solutions and values of a class of coupled nonconvex and nonsmooth empirical risk-minimization problems and (b) validate these properties by a noisy amplitude-based phase-retrieval problem, the latter being of much topical interest. Derived from available data via sampling, these empirical risk-minimization problems are the computational workhorse of a population risk model that involves the minimization of an expected value of a random functional. When these minimization problems are nonconvex, the computation of their globally optimal solutions is elusive. Together with the fact that the expectation operator cannot be evaluated for general probability distributions, it becomes necessary to justify whether the stationary solutions of the empirical problems are practical approximations of the stationary solution of the population problem. When these two features, general distribution and nonconvexity, are coupled with nondifferentiability that often renders the problems “non-Clarke regular,” the task of the justification becomes challenging. Our work aims to address such a challenge within an algorithm-free setting. The resulting analysis is, therefore, different from much of the analysis in the recent literature that is based on local search algorithms. Furthermore, supplementing the classical global minimizer-centric analysis, our results offer a promising step to close the gap between computational optimization and asymptotic analysis of coupled, nonconvex, nonsmooth statistical estimation problems, expanding the former with statistical properties of the practically obtained solution and providing the latter with a more practical focus pertaining to computational tractability.
- Published
- 2022
30. On Boundedness of Maximal Operators Associated with Hypersurfaces
- Author
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S E Usmanov and I A Ikromov
- Subjects
Statistics and Probability ,Pure mathematics ,Mathematics::Algebraic Geometry ,Hypersurface ,Mathematics::Complex Variables ,Applied Mathematics ,General Mathematics ,Mathematics::Classical Analysis and ODEs ,Regular polygon ,Mathematics::Differential Geometry ,General Medicine ,Value (mathematics) ,Mathematics - Abstract
In this paper, we obtain the criterion of boundedness of maximal operators associated with smooth hypersurfaces. Also we compute the exact value of the boundedness index of such operators associated with arbitrary convex analytic hypersurfaces in the case where the height of a hypersurface in the sense of A. N. Varchenko is greater than 2. Moreover, we obtain the exact value of the boundedness index for degenerated smooth hypersurfaces, i.e., for hypersurfaces satisfying conditions of the classical Hartman-Nirenberg theorem. The obtained results justify the Stein-Iosevich-Sawyer hypothesis for arbitrary convex analytic hypersurfaces as well as for smooth degenerated hypersurfaces. Also we discuss some related problems of the theory of oscillatory integrals.
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- 2022
31. Positivity preservers forbidden to operate on diagonal blocks
- Author
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Prateek Kumar Vishwakarma
- Subjects
Power series ,Applied Mathematics ,General Mathematics ,Diagonal ,Monotonic function ,Functional Analysis (math.FA) ,Mathematics - Functional Analysis ,Combinatorics ,Mathematics - Classical Analysis and ODEs ,Converse ,Classical Analysis and ODEs (math.CA) ,FOS: Mathematics ,15B48, 26A21 (primary), 15A24, 15A39, 15A45, 30B10 (secondary) ,Schur product theorem ,Mathematics - Abstract
The question of which functions acting entrywise preserve positive semidefiniteness has a long history, beginning with the Schur product theorem [Crelle 1911], which implies that absolutely monotonic functions (i.e., power series with nonnegative coefficients) preserve positivity on matrices of all dimensions. A famous result of Schoenberg and of Rudin [Duke Math. J. 1942, 1959] shows the converse: there are no other such functions. Motivated by modern applications, Guillot and Rajaratnam [Trans. Amer. Math. Soc. 2015] classified the entrywise positivity preservers in all dimensions, which act only on the off-diagonal entries. These two results are at "opposite ends", and in both cases the preservers have to be absolutely monotonic. We complete the classification of positivity preservers that act entrywise except on specified "diagonal/principal blocks", in every case other than the two above. (In fact we achieve this in a more general framework.) This yields the first examples of dimension-free entrywise positivity preservers - with certain forbidden principal blocks - that are not absolutely monotonic., Minor edits in exposition, 19 pages. The paper now uses the style file of Trans. AMS (to appear)
- Published
- 2023
32. Mixed 𝐴₂-𝐴_{∞} estimates of the non-homogeneous vector square function with matrix weights
- Author
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Sergei Treil
- Subjects
Matrix (mathematics) ,Applied Mathematics ,General Mathematics ,Non homogeneous ,Mathematical analysis ,Mathematics - Abstract
This paper extends the results from a work of Hytönen, Petermichl, and Volberg about sharp A 2 A_2 - A ∞ A_\infty estimates with matrix weights to the non-homogeneous situation.
- Published
- 2023
33. An uncountable Furstenberg–Zimmer structure theory
- Author
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Asgar Jamneshan, Jamneshan, Asgar (ORCID 0000-0002-1450-6569 & YÖK ID 332404), College of Sciences, and Department of Mathematics
- Subjects
Applied Mathematics ,General Mathematics ,Structure theory ,Measure preserving systems ,Ergodic theory ,Mathematics - Abstract
Furstenberg-Zimmer structure theory refers to the extension of the dichotomy between the compact and weakly mixing parts of a measure-preserving dynamical system and the algebraic and geometric descriptions of such parts to a conditional setting, where such dichotomy is established relative to a factor and conditional analogs of those algebraic and geometric descriptions are sought. Although the unconditional dichotomy and the characterizations are known for arbitrary systems, the relative situation is understood under certain countability and separability hypotheses on the underlying groups and spaces. The aim of this article is to remove these restrictions in the relative situation and establish a Furstenberg-Zimmer structure theory in full generality. As an independent byproduct, we establish a connection between the relative analysis of systems in ergodic theory and the internal logic in certain Boolean topoi., A.J. was supported by DFG-research fellowship JA 2512/3-1. A.J. offers his thanks to Terence Tao for suggesting this project, many helpful discussions, and his encouragement and support. He is grateful to Pieter Spaas for several helpful discussions. A.J. thanks Markus Haase for organizing an online workshop on structural ergodic theory where the results of this paper and the parallel work could be discussed, and Nikolai Edeko, Markus Haase, and Henrik Kreidler for helpful comments on an early version of the manuscript. A.J. is indebted to the anonymous referee for several useful suggestions and corrections.
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- 2022
34. Tractable Relaxations of Composite Functions
- Author
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Taotao He and Mohit Tawarmalani
- Subjects
General Mathematics ,Composite number ,Applied mathematics ,Function (mathematics) ,Management Science and Operations Research ,Hypograph ,Computer Science Applications ,Mathematics - Abstract
In this paper, we introduce new relaxations for the hypograph of composite functions assuming that the outer function is supermodular and concave extendable. Relying on a recently introduced relaxation framework, we devise a separation algorithm for the graph of the outer function over P, where P is a special polytope to capture the structure of each inner function using its finitely many bounded estimators. The separation algorithm takes [Formula: see text] time, where d is the number of inner functions and n is the number of estimators for each inner function. Consequently, we derive large classes of inequalities that tighten prevalent factorable programming relaxations. We also generalize a decomposition result and devise techniques to simultaneously separate hypographs of various supermodular, concave-extendable functions using facet-defining inequalities. Assuming that the outer function is convex in each argument, we characterize the limiting relaxation obtained with infinitely many estimators as the solution of an optimal transport problem. When the outer function is also supermodular, we obtain an explicit integral formula for this relaxation.
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- 2022
35. A curvature-free 𝐿𝑜𝑔(2𝑘-1) theorem
- Author
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Florent Balacheff and Louis Merlin
- Subjects
Discrete mathematics ,Lemma (mathematics) ,Applied Mathematics ,General Mathematics ,010102 general mathematics ,16. Peace & justice ,Curvature ,Mathematics::Geometric Topology ,01 natural sciences ,Volume entropy ,0103 physical sciences ,010307 mathematical physics ,0101 mathematics ,Mathematics - Abstract
This paper presents a curvature-free version of the Log ( 2 k − 1 ) \text {Log}(2k-1) Theorem of Anderson, Canary, Culler, and Shalen [J. Differential Geometry 44 (1996), pp. 738–782]. It generalizes a result by Hou [J. Differential Geometry 57 (2001), no. 1, pp. 173–193] and its proof is rather straightforward once we know the work by Lim [Trans. Amer. Math. Soc. 360 (2008), no. 10, pp. 5089–5100] on volume entropy for graphs. As a byproduct we obtain a curvature-free version of the Collar Lemma in all dimensions.
- Published
- 2023
36. CSP dichotomy for special triads
- Author
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Libor Barto, Miklós Maróti, Todd Niven, and Marcin Kozik
- Subjects
Discrete mathematics ,Conjecture ,triad ,Applied Mathematics ,General Mathematics ,Digraph ,Directed graph ,Computer Science::Computational Complexity ,Combinatorics ,TheoryofComputation_ANALYSISOFALGORITHMSANDPROBLEMCOMPLEXITY ,graph coloring ,Homomorphism ,Graph coloring ,Tree (set theory) ,constraint satisfaction problem ,Time complexity ,Constraint satisfaction problem ,MathematicsofComputing_DISCRETEMATHEMATICS ,Mathematics - Abstract
For a fixed digraph G, the Constraint Satisfaction Problem with the template G, or CSP(G) for short, is the problem of deciding whether a given input digraph H admits a homomorphism to G. The dichotomy conjecture of Feder and Vardi states that CSP(G), for any choice of G, is solvable in polynomial time or NP-complete. This paper confirms the conjecture for a class of oriented trees called special triads. As a corollary we get the smallest known example of an oriented tree (with 33 vertices) defining an NP-complete CSP(G).
- Published
- 2023
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37. Members of thin Π₁⁰ classes and generic degrees
- Author
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Guohua Wu, Bowen Yuan, Frank Stephan, and School of Physical and Mathematical Sciences
- Subjects
Mathematics [Science] ,Pure mathematics ,Turing Degrees ,Applied Mathematics ,General Mathematics ,Pi ,Genericity ,Mathematics - Abstract
A Π 1 0 \Pi ^{0}_{1} class P P is thin if every Π 1 0 \Pi ^{0}_{1} subclass Q Q of P P is the intersection of P P with some clopen set. In 1993, Cenzer, Downey, Jockusch and Shore initiated the study of Turing degrees of members of thin Π 1 0 \Pi ^{0}_{1} classes, and proved that degrees containing no members of thin Π 1 0 \Pi ^{0}_{1} classes can be recursively enumerable, and can be minimal degree below 0 ′ \mathbf {0}’ . In this paper, we work on this topic in terms of genericity, and prove that all 2-generic degrees contain no members of thin Π 1 0 \Pi ^{0}_{1} classes. In contrast to this, we show that all 1-generic degrees below 0 ′ \mathbf {0}’ contain members of thin Π 1 0 \Pi ^{0}_{1} classes.
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- 2022
38. Gradient weighted norm inequalities for very weak solutions of linear parabolic equations with BMO coefficients
- Author
-
Le Trong Thanh Bui and Quoc-Hung Nguyen
- Subjects
010101 applied mathematics ,General Mathematics ,Norm (mathematics) ,010102 general mathematics ,Mathematics::Analysis of PDEs ,Applied mathematics ,0101 mathematics ,01 natural sciences ,Parabolic partial differential equation ,Mathematics - Abstract
In this paper, we give a short proof of the Lorentz estimates for gradients of very weak solutions to the linear parabolic equations with the Muckenhoupt class A q -weights u t − div ( A ( x , t ) ∇ u ) = div ( F ) , in a bounded domain Ω × ( 0 , T ) ⊂ R N + 1 , where A has a small mean oscillation, and Ω is a Lipchistz domain with a small Lipschitz constant.
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- 2022
39. On improved bounds and conditions for the convergence of Markov chains
- Author
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Alexander Yur'evich Veretennikov and Mariya Aleksandrovna Veretennikova
- Subjects
Markov chain ,General Mathematics ,Convergence (routing) ,Applied mathematics ,Mathematics - Abstract
We continue the work of improving the rate of convergence of ergodic homogeneous Markov chains. The setting is more general than in previous papers: we are able to get rid of the assumption about a common dominating measure and consider the case of inhomogeneous Markov chains as well as more general state spaces. We give examples where the new bound for the rate of convergence is the same as (resp. better than) the classical Markov–Dobrushin inequality.
- Published
- 2022
40. Large Deviations for the Single-Server Queue and the Reneging Paradox
- Author
-
Ruoyu Wu, Paul Dupuis, Amarjit Budhiraja, and Rami Atar
- Subjects
Statement (computer science) ,Scale (ratio) ,General Mathematics ,010102 general mathematics ,Single server queue ,Management Science and Operations Research ,01 natural sciences ,Computer Science Applications ,010104 statistics & probability ,Laplace principle ,Applied mathematics ,Large deviations theory ,0101 mathematics ,Unit (ring theory) ,Mathematics - Abstract
For the M/M/1+M model at the law-of-large-numbers scale, the long-run reneging count per unit time does not depend on the individual (i.e., per customer) reneging rate. This paradoxical statement has a simple proof. Less obvious is a large deviations analogue of this fact, stated as follows: the decay rate of the probability that the long-run reneging count per unit time is atypically large or atypically small does not depend on the individual reneging rate. In this paper, the sample path large deviations principle for the model is proved and the rate function is computed. Next, large time asymptotics for the reneging rate are studied for the case when the arrival rate exceeds the service rate. The key ingredient is a calculus of variations analysis of the variational problem associated with atypical reneging. A characterization of the aforementioned decay rate, given explicitly in terms of the arrival and service rate parameters of the model, is provided yielding a precise mathematical description of this paradoxical behavior.
- Published
- 2022
41. Linear damping and depletion in flowing plasma with strong sheared magnetic fields
- Author
-
Han Liu, Nader Masmoudi, Weiren Zhao, and Cuili Zhai
- Subjects
Applied Mathematics ,General Mathematics ,Plasma ,Mechanics ,Magnetohydrodynamics ,Stability (probability) ,Mathematics ,Magnetic field - Abstract
In this paper, we study the long-time behavior of the solution for the linearized ideal MHD around sheared velocity and magnetic field under Stern stability condition. We prove that the velocity and magnetic field will converge to sheared velocity and magnetic field as time approaches infinity. Moreover a new depletion phenomenon is proved: the horizontal velocity and magnetic field at the critical points will decay to 0 as time approaches infinity.
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- 2022
42. Optimal Stopping of a Random Sequence with Unknown Distribution
- Author
-
Alexander Goldenshluger and Assaf Zeevi
- Subjects
Independent and identically distributed random variables ,Sequence ,Distribution (number theory) ,General Mathematics ,Stopping rule ,Applied mathematics ,Optimal stopping ,Management Science and Operations Research ,Random sequence ,Computer Science Applications ,Mathematics - Abstract
The subject of this paper is the problem of optimal stopping of a sequence of independent and identically distributed random variables with unknown distribution. We propose a stopping rule that is based on relative ranks and study its performance as measured by the maximal relative regret over suitable nonparametric classes of distributions. It is shown that the proposed rule is first-order asymptotically optimal and nearly rate optimal in terms of the rate at which the relative regret converges to zero. We also develop a general method for numerical solution of sequential stopping problems with no distributional information and use it in order to implement the proposed stopping rule. Some numerical experiments illustrating performance of the rule are presented as well.
- Published
- 2022
43. Rouché’s theorem and the geometry of rational functions
- Author
-
Trevor Richards
- Subjects
Pure mathematics ,Applied Mathematics ,General Mathematics ,Rouché's theorem ,Rational function ,Mathematics - Abstract
In this paper, we use Rouché’s theorem and the pleasant properties of the arithmetic of the logarithmic derivative to establish several new results and bounds regarding the geometry of the zeros, poles, and critical points of a rational function. Included is an improvement on a result by Alexander and Walsh regarding the “exclusion region” around a given zero or pole of a rational function in which no critical point may lie.
- Published
- 2022
44. Maps on positive definite cones of 𝐶*-algebras preserving the Wasserstein mean
- Author
-
Lajos Molnár
- Subjects
Pure mathematics ,Applied Mathematics ,General Mathematics ,Positive-definite matrix ,Mathematics - Abstract
The primary aim of this paper is to present the complete description of the isomorphisms between positive definite cones of C ∗ C^* -algebras with respect to the recently introduced Wasserstein mean and to show the nonexistence of nonconstant such morphisms into the positive reals in the case of von Neumann algebras without type I 2 _2 , I 1 _1 direct summands. A comment on the algebraic properties of the Wasserstein mean relating associativity is also made.
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- 2022
45. Global dynamics and bifurcation analysis of a fractional‐order SEIR epidemic model with saturation incidence rate
- Author
-
Parvaiz Ahmad Naik, Muhammad Bilal Ghori, Zohre Eskandari, Jian Zu, and Mehraj-ud-din Naik
- Subjects
education.field_of_study ,General Mathematics ,Population ,Feasible region ,General Engineering ,Stability (probability) ,Fractional calculus ,Bounded function ,Applied mathematics ,education ,Epidemic model ,Basic reproduction number ,Bifurcation ,Mathematics - Abstract
The present paper studies a fractional-order SEIR epidemic model for the transmission dynamics of infectious diseases such as HIV and HBV that spreads in the host population. The total host population is considered bounded, and Holling type-II saturation incidence rate is involved as the infection term. Using the proposed SEIR epidemic model, the threshold quantity, namely basic reproduction number R0, is obtained that determines the status of the disease, whether it dies out or persists in the whole population. The model’s analysis shows that two equilibria exist, namely, disease-free equilibrium (DFE) and endemic equilibrium (EE). The global stability of the equilibria is determined using a Lyapunov functional approach. The disease status can be verified based on obtained threshold quantity R0. If R0 < 1, then DFE is globally stable, leading to eradicating the population’s disease. If R0 > 1, a unique EE exists, and that is globally stable under certain conditions in the feasible region. The Caputo type fractional derivative is taken as the fractional operator. The bifurcation and sensitivity analyses are also performed for the proposed model that determines the relative importance of the parameters into disease transmission. The numerical solution of the model is obtained by the generalized Adams- Bashforth-Moulton method. Finally, numerical simulations are performed to illustrate and verify the analytical results.
- Published
- 2022
46. Potential theory for a class of strongly degenerate parabolic operators of Kolmogorov type with rough coefficients
- Author
-
Malte Litsgård and Kaj Nyström
- Subjects
Dirichlet problem ,Pure mathematics ,Applied Mathematics ,General Mathematics ,Degenerate energy levels ,Boundary (topology) ,Mathematical Analysis ,Kolmogorov equation ,Type (model theory) ,Lipschitz continuity ,Operators in divergence form ,Lipschitz domain ,Parabolic partial differential equation ,Dilation (operator theory) ,Mathematics - Analysis of PDEs ,Matematisk analys ,Bounded function ,FOS: Mathematics ,Parabolic ,Analysis of PDEs (math.AP) ,35K65, 35K70, 35H20, 35R03 ,Mathematics - Abstract
In this paper we develop a potential theory for strongly degenerate parabolic operators of the form L : = ∇ X ⋅ ( A ( X , Y , t ) ∇ X ) + X ⋅ ∇ Y − ∂ t , in unbounded domains of the form Ω = { ( X , Y , t ) = ( x , x m , y , y m , t ) ∈ R m − 1 × R × R m − 1 × R × R | x m > ψ ( x , y , y m , t ) } , where ψ is assumed to satisfy a uniform Lipschitz condition adapted to the dilation structure and the (non-Euclidean) Lie group underlying the operator L . Concerning A = A ( X , Y , t ) we assume that A is bounded, measurable, symmetric and uniformly elliptic (as a matrix in R m ). Beyond the solvability of the Dirichlet problem and other fundamental properties our results include scale and translation invariant boundary comparison principles, boundary Harnack inequalities and doubling properties of associated parabolic measures. All of our estimates are translation- and scale-invariant with constants only depending on the constants defining the boundedness and ellipticity of A and the Lipschitz constant of ψ. Our results represent a version, for operators of Kolmogorov type with bounded, measurable coefficients, of the by now classical results of Fabes and Safonov, and several others, concerning boundary estimates for uniformly parabolic equations in (time-dependent) Lipschitz type domains.
- Published
- 2022
47. Global attractivity for uncertain differential systems
- Author
-
Nana Tao and Chunxiao Ding
- Subjects
sufficient condition ,General Mathematics ,Uncertainty theory ,Differential systems ,interest rate model with uncertainty ,uncertain differential systems ,Alpha (programming language) ,α-path ,Short-rate model ,QA1-939 ,Applied mathematics ,global attractivity ,Mathematics - Abstract
This paper studies global attractivity for uncertain differential systems, which are effective tools to solve the problems with uncertainty. And They have been applied in many areas. This article presents several global attractivity concepts. Based on the knowledge of uncertainty theory, some sufficient conditions of global attractivity for linear uncertain differential systems are given. In particular, the attractivity on the solutions and $ \alpha $-path of uncertain differential systems is studied. Last, as an application of attractivity, an interest rate model with uncertainty is shown.
- Published
- 2022
48. A general form for precise asymptotics for complete convergence under sublinear expectation
- Author
-
Xue Ding
- Subjects
Sublinear function ,General Mathematics ,complete convergence ,Convergence (routing) ,QA1-939 ,sublinear expectation ,Applied mathematics ,precise asymptotics ,Mathematics - Abstract
Let $ \{X_n, n\geq 1\} $ be a sequence of independent and identically distributed random variables in a sublinear expectation $ (\Omega, \mathcal H, {\mathbb {\widehat{E}}}) $ with a capacity $ {\mathbb V} $ under $ {\mathbb {\widehat{E}}} $. In this paper, under some suitable conditions, I show that a general form of precise asymptotics for complete convergence holds under sublinear expectation. It can describe the relations among the boundary function, weighted function, convergence rate and limit value in studies of complete convergence. The results extend some precise asymptotics for complete convergence theorems from the traditional probability space to the sublinear expectation space. The results also generalize the known results obtained by Xu and Cheng [34].
- Published
- 2022
49. A two-grid mixed finite volume element method for nonlinear time fractional reaction-diffusion equations
- Author
-
Ruixia Du, Zhichao Fang, Yang Liu, and Hong Li
- Subjects
l1-formula ,browder fixed point theorem ,General Mathematics ,Fixed-point theorem ,error estimate ,Space (mathematics) ,Grid ,Domain (mathematical analysis) ,Fractional calculus ,Nonlinear system ,time fractional reaction-diffusion equations ,Reaction–diffusion system ,QA1-939 ,Applied mathematics ,Uniqueness ,two-grid mixed finite volume element algorithm ,Mathematics - Abstract
In this paper, a two-grid mixed finite volume element (MFVE) algorithm is presented for the nonlinear time fractional reaction-diffusion equations, where the Caputo fractional derivative is approximated by the classical $ L1 $-formula. The coarse and fine grids (containing the primal and dual grids) are constructed for the space domain, then a nonlinear MFVE scheme on the coarse grid and a linearized MFVE scheme on the fine grid are given. By using the Browder fixed point theorem and the matrix theory, the existence and uniqueness for the nonlinear and linearized MFVE schemes are obtained, respectively. Furthermore, the stability results and optimal error estimates are derived in detailed. Finally, some numerical results are given to verify the feasibility and effectiveness of the proposed algorithm.
- Published
- 2022
50. A note on a ZIKV epidemic model with spatial structure and vector-bias
- Author
-
Yifei Pan, Siyao Zhu, and Jinliang Wang
- Subjects
threshold dynamics ,Geography ,basic reproduction number ,Spatial structure ,General Mathematics ,Vector (epidemiology) ,spatial heterogeneity ,QA1-939 ,Applied mathematics ,Epidemic model ,Mathematics ,global asymptotic stability - Abstract
This paper provides a supplement to a recent study of (Appl. Math. Lett. 80 (2020) 106052). We further verify that the unique endemic equilibrium is globally asymptotically stable whenever it exists.
- Published
- 2022
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